WO2001089279A1 - Apparatus and method for verifying axially leaded circuit components - Google Patents

Apparatus and method for verifying axially leaded circuit components Download PDF

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Publication number
WO2001089279A1
WO2001089279A1 PCT/SG2000/000071 SG0000071W WO0189279A1 WO 2001089279 A1 WO2001089279 A1 WO 2001089279A1 SG 0000071 W SG0000071 W SG 0000071W WO 0189279 A1 WO0189279 A1 WO 0189279A1
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WO
WIPO (PCT)
Prior art keywords
component
axially leaded
circuit components
axially
leaded circuit
Prior art date
Application number
PCT/SG2000/000071
Other languages
French (fr)
Inventor
Kiyoshi Imai
Yu Chang Wang
Boon Hai Daniel Teo
Cheng Sheng Chai
Masashi Miyake
Original Assignee
Matsushita Technology (S) Pte. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Technology (S) Pte. Ltd. filed Critical Matsushita Technology (S) Pte. Ltd.
Priority to AU2000246383A priority Critical patent/AU2000246383A1/en
Priority to PCT/SG2000/000071 priority patent/WO2001089279A1/en
Publication of WO2001089279A1 publication Critical patent/WO2001089279A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/01—Subjecting similar articles in turn to test, e.g. "go/no-go" tests in mass production; Testing objects at points as they pass through a testing station
    • G01R31/013—Testing passive components

Definitions

  • This invention relates to the manufacture of circuit assemblies and, in particular, to the verification of circuit components in manufacturing assembly lines.
  • circuit components are soldered onto circuit substrates to form circuit assemblies.
  • circuit components are typically picked from component cassettes and placed onto a circuit substrate in preparation for soldering. The circuit components are then soldered onto the circuit substrate.
  • a problem that can occur in forming circuit assemblies is that incorrect circuit components may be used. Consequently, rectifying this problem requires tedious re-working to remove the incorrect circuit components. Thereafter, correct circuit components are re-s ⁇ ldered onto the circuit substrates to form the circuit assemblies. Hence, verifying or testing circuit components prior to placement or soldering onto circuit substrates can alleviate the need for such re-working.
  • Circuit components can be verified by visual inspections.
  • the circuit components may be colour coded for identification with the visual inspections.
  • visual inspections are prone to human errors or cannot be performed by those who are, for example, colour blind.
  • colour coding of circuit components is not standardized and keeps changing, then associating colour codes to circuit components require constant re-learning and this is unproductive.
  • US Patent No. 4,119,206 issued to Woodman, Jr. et al on October 10 th 1978, describes a non- visual mechanism with a testing device adjacent a conveyor to test successive, spaced components.
  • the conveyor is stopped in the event that a component fails testing.
  • downtime in an assembly line is undesirable because circuit assemblies cannot be manufactured during the downtime.
  • circuit components are now more reliably packaged so that checking each and every circuit component may be unnecessary.
  • a sampling check of at least one circuit component in a packaged lot that is ready for placement is generally sufficient as a quality control.
  • circuit components in the packaged lot may be subjected to environmental factors that can affect specified values of such circuit components.
  • environmental factors include temperature, humidity or contamination during storage or transport.
  • testing typically requires the use of probes, such as probes or pings, to engage electrodes extending from a body of an axially leaded circuit component.
  • probes such as probes or pings
  • Such testing is affected by conditions of the probes or the manner in which contact is made by the probes against the electrodes. Consequently, different ways of testing or different types of probes generally cause differences in measuring specified values of the circuit components.
  • an apparatus for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine includes:
  • the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
  • the receiving means can include means for displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component.
  • the detecting means can include means for detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
  • the deriving means can include includes means for deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
  • the determining means can include means for generating a component acceptance signal when outcome of the comparing is within a predetermined tolerance range.
  • the determining means can include means for generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
  • a method for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine including the steps of:
  • the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
  • the receiving step can include the step of displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component.
  • the detecting step can include the step of detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
  • the deriving step can include the step of deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
  • the determining step can include the step of generating a component acceptance signal when outcome of the comparing step is within a predetermined tolerance range.
  • the determining step can include the step of generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
  • a computer program product with a computer usable medium having a computer readable program code means embodied therein for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, the computer program product including:
  • computer readable program code means for receiving a component signal from a controller of the placement machine, the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
  • the computer readable program code means for receiving can include computer readable program code means for displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component.
  • the computer readable program code means for detecting can include computer readable program code means for detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
  • the computer readable program code means for deriving can include computer readable program code means for deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
  • the computer readable program code means for determining can include computer readable program code means for generating a component acceptance signal when outcome of the comparing is within a predetermined tolerance range.
  • the computer readable program code means for determining can include computer readable program code means for generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
  • FIG. 1 is a schematic block diagram illustrating a placement machine having an apparatus in accordance with a preferred embodiment of the invention
  • FIG. 2 is plan view of an illustrative example of a reference component substrate for the apparatus of FIG. 1;
  • FIG. 3 shows circuit schematic of a comparator of the apparatus of FIG. 1 and two axially leaded circuit components and a power supply coupled to the comparator;
  • FIGs. 4a and 4b are, respectively, a plan view and a side view of an illustrative example of a test jig for the apparatus of FIG. 1;
  • FIG. 5 is a flowchart illustrating a method for verifying axially leaded circuit components using the apparatus of FIG. 1;
  • FIG. 6 is a block diagram of a computer system capable of implementing the method of FIG. 5.
  • One advantage is that axially leaded circuit components are verified offline without stopping placement of other circuit components by the placement machine. This, therefore, reduces downtime of the placement machine of the preferred embodiment.
  • Another advantage of the preferred embodiment of the invention is that the axially leaded circuit components for replenishing depleted circuit components are verified against reference components using a half- voltage measurement technique. Hence, variations in a manufacturer's specified values for a circuit component as a result of environmental factors affecting the specified values are overcome or at least alleviated.
  • the half- voltage measurement technique also overcomes or at least alleviates the limitation of conventional testing in which conditions of probes or the manner in which contact is made by such probes against electrodes of a circuit component causes variations in measurements.
  • a further advantage of the preferred embodiment of the invention is that circuit components can be more reliably verified without having to rely on colour coding. Hence, those who are colour blind can use the preferred embodiment of the invention to verify circuit components. In addition, associating colour codes to circuit components is unnecessary and verification of such circuit components is therefore simpler.
  • the placement machine 10 also includes a controller 12 and component storage locations 13 represented by a single block.
  • the controller 12 monitors placement of such axially leaded circuit components by a placement member 14. These axially leaded circuit components are selected or picked from the component storage locations 13 for placement onto circuit substrates by the controller 12.
  • the component storage locations 13 can be, for example, cassettes in which axially leaded circuit components in a tape-and-reel format are placed. Typically, the axially leaded circuit components are individually discharged from a cartridge (not shown) at an open-ended portion of such cassettes. The cartridge holds one end of a reel of axially leaded circuit components.
  • the apparatus 11 further includes a controller input port 15 at which control signals from the controller 12 are received, a processor 16 to process such control signals, a reference component substrate 17 mounted with a plurality of reference components and a comparator 18 coupled to the processor 16 and the reference component substrate 17.
  • the apparatus 11 also includes a display 19 for displaying indication signals associated with the control signals and test ports 20 at which output signals from the comparator are coupled to a test jig 21.
  • the test jig 21 has a conductor 22 to electrically conduct signals via the test port 20.
  • FIG. 2 is a plan view of an illustrative example of the reference component substrate 17.
  • the reference component substrate 17 includes an interface connector 23 for selectably providing a plurality of connections to the processor 16.
  • a reference component 26 is indicated.
  • Associated with the reference component 26 are two indicia 27,28. These two indicia are labelled '1' and '61 ' respectively and correspond to cassettes of the component storage locations 13.
  • the reference component substrate 17 can be mounted with sixty reference components corresponding to sixty cassettes.
  • the placement machine 10 can support more than sixty cassettes and, hence, more than one reference component substrate 17 can be used. Accordingly, different circuit assemblies can be manufactured with the more than one reference component substrate 17 depending on circuit components that are needed for the different circuit assemblies.
  • FIG. 3 a circuit schematic of the comparator 18 of the apparatus 11 is shown.
  • the comparator 18 includes a variable resistor 30 and an operational amplifier 31 having two comparator inputs 32,33.
  • the comparator input 32 is connected to an electrode 34 of the variable resistor 30.
  • Another electrode 35 of the variable resistor 30 is connected to a voltage supply 36 for apparatus 11 via node 37. From the test port 20a, the electrode 35 also connects to a signal line 22a of the conductor 22.
  • the signal line 22a connects to a probe 38 of the test jig 21 (not shown).
  • the comparator input 33 is connected to another signal line 22b via the test port 20b.
  • the signal line 22b connects to a probe 39 of the test jig 21 (not shown).
  • the comparator input 33 is also connected to the interface connector 23 at node 40.
  • the processor 16 controls the interface connector 23 to select one of the plurality of connections to thereby connect to, for example, the reference component 26 of the reference component substrate 17.
  • the axially leaded circuit component 42 forms a voltage divider with the reference component 26 from which the comparator 18 receives voltage signals via the comparator inputs 32,33.
  • the node 40 is common to both the axially leaded circuit component 42 and the reference component 26.
  • a voltage signal is derived at the node 40. This voltage signal is provided to the comparator input 33.
  • a reference voltage signal is derived using the variable resistor 30 coupled to the axially leaded circuit component 42.
  • the voltage supply 36 supplies the necessary voltage to provide both the voltage signal at the comparator input 33 and the reference voltage signal at the comparator input 32.
  • a comparison of the voltage signal and the reference voltage signal is then performed within the operational amplifier 31.
  • the test jig 21 at which a reel of axially leaded circuit components are received for verification has the test probes 38,39.
  • a plan view and a side view of an illustrative example of the test jig 21 are shown in FIG. 4a and FIG. 4b, respectively.
  • One side 44 of the test jig is indicated in the plan view to provide a reference for the side view.
  • the test jig 21 also includes three indication outputs 45,46,47 for indicating whether the axially leaded circuit component 42 is acceptable to replenish supply of a depleted axially leaded circuit component for the placement machine 10.
  • the conductor 22 extends from another side 48 of the test jig 21.
  • a flowchart illustrates a method 50 for verifying axially leaded circuit components using the apparatus 11.
  • the controller 12 generates a component signal when one of the component storage locations 13 is depleted.
  • This component signal is a control signal provided to the controller input 15 and indicates a depleted axially leaded circuit component.
  • the method 50 continues to step 52 at which the component signal is received by the processor 16 at the controller input port 15.
  • the processor 16 provides at least one indication signal associated with the component signal.
  • the at least one indication signal is provided to the display 19 for displaying, for example, ' 1 ' to indicate that the depleted axially leaded circuit component corresponds to cassette ' 1 ' in the component storage locations 13.
  • the method 50 then continues to step 53 at which a reference component is identified that is associated with the depleted axially leaded circuit component. Specifically, the identifying step identifies the reference component at location ' 1 ' of the reference component substrate 17. Upon identification of the reference component, the method 50 continues to step 54 at which the processor 16 detects an electrical coupling of one of a plurality of axially leaded circuit components to the reference component. To simplify description of the method 50, the one of a plurality of axially leaded circuit components is referred to as the axially leaded circuit component 42.
  • the plurality of axially leaded circuit components is to replenish supply of the depleted axially leaded circuit component of, for example, the cassette '1' of the component storage locations 13.
  • This plurality of axially leaded circuit components is typically provided in a tape-and-reel format with the axially leaded circuit component being one of such circuit components.
  • Detecting the electrical coupling at step 54 includes detecting that a series connection has been made from the axially leaded circuit component 42 to the reference component.
  • the processor 16 then derives a voltage signal, at step 55.
  • the voltage signal is derived at the node 49 that is common to both the axially leaded circuit component 42 and the reference component.
  • method 50 continues to step 56 at which the processor 16 controls the comparator 18 to perform a comparison of the voltage signal with the reference voltage signal.
  • the voltage signal is provided to the comparator input 32 and the reference voltage signal is provided to the comparator input 33.
  • the processor 16 determines whether to reject the plurality of axially leaded circuit components at decision step 57.
  • This determining step 57 requires setting the variable resistor 30 such that outcome of the comparison can be variably set based on a predetermined tolerance range.
  • the predetermined tolerance range depends on specifications of the plurality of axially leaded circuit components.
  • the processor 16 then generates a component acceptance signal at step 58. Otherwise, with a 'No' from decision step 57, the outcome from comparing thus exceeds the predetermined tolerance range. Consequently, the processor 16 then generates a component rejection signal at step 59.
  • the apparatus 11 in the preferred embodiment of the invention can be implemented using a computer program product such as, for example, a computer system 60 as shown in FIG. 6.
  • the method 50 can be implemented as software, or computer readable program code, executing on the computer system 60.
  • the computer system 60 includes the controller input 15, the processor 16, the reference component substrate 17, the comparator 18, the display 19, and the test jig 21.
  • the computer system 60 further includes input devices 61,62.
  • a communication input/output (I/O) signal bus 63 provides for control signals between the processor 16 and the controller 12.
  • the computer system 60 also includes a memory 64 that may include random access memory (RAM) and read-only memory (ROM), an input/output (I/O) interface 65 and one or more storage devices represented with a single block as a storage device 66.
  • the memory 64 can be used to store the settings for the predetermined tolerance range once such a range is set.
  • a common bus 67 links elements of the computer system 60 to provide data transfers when processing data based on voltage signals.
  • User input to operate the computer system 60 can be provided by one or more of the input devices 61,62 via the I/O interface 65.
  • a user of the computer system 60 can use a keyboard as the input device 61 and/or a pointing device such as a mouse as the input device 62.
  • the keyboard and the mouse provide input to the computer system 60.
  • the storage device 66 can consist of one or more of the following: a floppy disk, a hard disk drive, a magneto-optical disk drive, CD- ROM, magnetic tape or any other of a number of non- volatile storage devices well known to those skilled in the art.
  • Each of the elements in the computer system 60 is typically connected to other devices via the common bus 67 that in turn can consist of data, address, and control buses.
  • the method is effected by instructions in the software that are carried out by the computer system 60.
  • the software may be implemented as one or more modules for implementing the method steps. That is, the processor 16 can be a part of a computer readable program code that usually performs a particular function or related functions.
  • the software may be stored in a computer readable medium, including the storage device 66.
  • the computer system 60 includes the computer readable medium having such software or program code recorded such that instructions of the software or the program code can be carried out.
  • the use of the computer system 60 preferably effects advantageously the apparatus 11 to verify axially leaded circuit components prior to placement onto circuit substrates by the placement machine 10.
  • the computer system 60 is simply provided for illustrative purposes only and other configurations can be employed without departing from the scope and spirit of the invention.
  • the foregoing is merely an example of the types of computers or computer systems with which the embodiments of the invention maybe practised.
  • the method 50 of the embodiments are resident as software or a computer readable program code recorded on a hard disk drive (such as the storage device 66) as the computer readable medium, and read and controlled using the processor 16.
  • Intermediate storage of the program code and media content data and any data fetched from the network may be accomplished using the memory 64, possibly in concert with the storage device 66.
  • the program may be supplied to the user encoded on a
  • CD-ROM or a floppy disk both generally depicted by the storage device 66
  • the computer system 60 can load the software from other computer readable media.
  • This may include magnetic tape, a ROM or integrated circuit, a magneto-optical disk, a radio or infra-red transmission channel between the computer and another device, a computer readable card such as a PCMCIA card, and the Internet and Intranets including email transmissions and information recorded on Internet sites and the like.
  • a computer readable media such as a PCMCIA card
  • Internet and Intranets including email transmissions and information recorded on Internet sites and the like.
  • the placement machine 10 and the apparatus 1 las described in the above preferred embodiment of the invention advantageously overcomes or at least alleviates one or more of the disadvantages of conventional placement machines and conventional methods of verifying axially leaded circuit components prior to placement onto circuit substrates.
  • the apparatus 11, the method 50 and a computer program product such as, for example, the computer system 60 for verifying axially leaded circuit components prior to placement onto circuit substrates by the placement machine 10 in accordance with a preferred embodiment of the invention are described.
  • the preferred embodiment is described, it shall be apparent to one skilled in the art in view of this preferred embodiment that numerous changes and/or modifications can be made without departing from the scope and spirit of the invention.

Abstract

A placement machine (10) with an apparatus (11), a controller (12) and component storage locations (13) is described. Controller (12) monitors placement of axially leaded circuit components, selected or picked from storage locations (13), onto circuit substrates by a placement member (14). Apparatus (11) has a controller input port (15) at which control signals from controller (12) are received. A processor (16) of apparatus (11) processes a control component signal, associated with a depleted component, to identify a reference component mounted on a reference component substrate (17). Thereafter, processor (16) detects an electrical coupling of an axially leaded circuit component from a plurality of axially leaded circuit components to replace a depleted axially leaded circuit component required for placement by placement machine (10). The plurality of axially leaded circuit components is verified using a half voltage measurement technique in which the axially leaded circuit component is connected in series with the reference component.

Description

APPARATUS AND METHOD FOR VERIFYING AXIALLY LEADED CIRCUIT COMPONENTS
Field of the Invention This invention relates to the manufacture of circuit assemblies and, in particular, to the verification of circuit components in manufacturing assembly lines.
Background
Conventionally, circuit components are soldered onto circuit substrates to form circuit assemblies. In forming a circuit assembly, such circuit components are typically picked from component cassettes and placed onto a circuit substrate in preparation for soldering. The circuit components are then soldered onto the circuit substrate.
A problem that can occur in forming circuit assemblies is that incorrect circuit components may be used. Consequently, rectifying this problem requires tedious re-working to remove the incorrect circuit components. Thereafter, correct circuit components are re-sόldered onto the circuit substrates to form the circuit assemblies. Hence, verifying or testing circuit components prior to placement or soldering onto circuit substrates can alleviate the need for such re-working.
Circuit components can be verified by visual inspections. For example, the circuit components may be colour coded for identification with the visual inspections. However, such visual inspections are prone to human errors or cannot be performed by those who are, for example, colour blind. Furthermore, when colour coding of circuit components is not standardized and keeps changing, then associating colour codes to circuit components require constant re-learning and this is unproductive.
US Patent No. 4,119,206, issued to Woodman, Jr. et al on October 10th 1978, describes a non- visual mechanism with a testing device adjacent a conveyor to test successive, spaced components. However, in US Patent No. 4,119,206, the conveyor is stopped in the event that a component fails testing. As is known in the art, downtime in an assembly line is undesirable because circuit assemblies cannot be manufactured during the downtime.
Further to the above, circuit components are now more reliably packaged so that checking each and every circuit component may be unnecessary. Hence, a sampling check of at least one circuit component in a packaged lot that is ready for placement is generally sufficient as a quality control.
What is more critical, however, is that the circuit components in the packaged lot may be subjected to environmental factors that can affect specified values of such circuit components. Such environmental factors include temperature, humidity or contamination during storage or transport. Thus, verifying or testing circuit components based on specified values provided by component specifications could fail because of changes to the specified values.
For axially leaded circuit components, testing typically requires the use of probes, such as probes or pings, to engage electrodes extending from a body of an axially leaded circuit component. Such testing is affected by conditions of the probes or the manner in which contact is made by the probes against the electrodes. Consequently, different ways of testing or different types of probes generally cause differences in measuring specified values of the circuit components.
Therefore, in view of the above problems, what is needed is an apparatus and a method that overcome, or at least alleviate, the above problems or limitations in order to more accurately verify axially leaded circuit components prior to placement onto circuit substrates without increasing manufacturing downtime.
Summary hi accordance with one aspect of the invention, there is disclosed an apparatus for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, the apparatus includes:
means for receiving a component signal from a controller of the placement machine, the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
means for identifying a reference component associated with the depleted axially leaded circuit component;
means for detecting an electrical coupling of one of a plurality of axially leaded circuit components to the reference component, the plurality of axially leaded circuit components being to replenish supply of the depleted axially leaded circuit component for the placement;
means for deriving a voltage signal at a node common to both the one of the plurality of axially leaded circuit components and the reference component;
means for comparing the voltage signal with a reference voltage signal;
and
means for determining whether to reject the plurality of axially leaded circuit components in response to a comparison performed by the comparing means.
Generally, the receiving means can include means for displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component. Typically, the detecting means can include means for detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
Generally, the deriving means can include includes means for deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
Typically, the determining means can include means for generating a component acceptance signal when outcome of the comparing is within a predetermined tolerance range.
Generally, the determining means can include means for generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
In accordance with another aspect of the invention, there is disclosed a method for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, the method including the steps of:
receiving a component signal from a controller of the placement machine, the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
identifying a reference component associated with the depleted axially leaded circuit component;
detecting an electrical coupling of one of a plurality of axially leaded circuit components to the reference component, the plurality of axially leaded circuit components being to replenish supply of the depleted axially leaded circuit component for the placement;
deriving a voltage signal at a node common to both the one of the plurality of axially leaded circuit components and the reference component;
comparing the voltage signal with a reference voltage signal;
and
determining whether to reject the plurality of axially leaded circuit components in response to the comparing step.
Generally, the receiving step can include the step of displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component.
Typically, the detecting step can include the step of detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
Generally, the deriving step can include the step of deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
Typically, the determining step can include the step of generating a component acceptance signal when outcome of the comparing step is within a predetermined tolerance range. Generally, the determining step can include the step of generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
In accordance with a further aspect of the invention, there is disclosed a computer program product with a computer usable medium having a computer readable program code means embodied therein for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, the computer program product including:
computer readable program code means for receiving a component signal from a controller of the placement machine, the component signal being indicative of a depleted axially leaded circuit component, the depleted axially leaded circuit component being for placement onto the circuit substrates;
computer readable program code means for identifying a reference component associated with the depleted axially leaded circuit component;
computer readable program code means for detecting an electrical coupling of one of a plurality of axially leaded circuit components to the reference component, the plurality of axially leaded circuit components being to replenish supply of the depleted axially leaded circuit component for the placement;
computer readable program code means for deriving a voltage signal at a node common to both the one of the plurality of axially leaded circuit components and the reference component;
computer readable program code means for comparing the voltage signal with a reference voltage signal;
and computer readable program code means for determining whether to reject the plurality of axially leaded circuit components in response to a comparison performed by the computer readable program code means for comparing.
Generally, the computer readable program code means for receiving can include computer readable program code means for displaying at least one indication signal, the indication signal being indicative of the depleted axially leaded circuit component.
Typically, the computer readable program code means for detecting can include computer readable program code means for detecting a connection of the one of the plurality of axially leaded circuit components in series with the reference component.
Generally, the computer readable program code means for deriving can include computer readable program code means for deriving the reference voltage signal using a variable resistor connected to the one of the plurality of axially leaded circuit components.
Typically, the computer readable program code means for determining can include computer readable program code means for generating a component acceptance signal when outcome of the comparing is within a predetermined tolerance range.
Generally, the computer readable program code means for determining can include computer readable program code means for generating a component rejection signal when outcome of the comparing exceeds a predetermined tolerance range.
Brief Description of the Drawings
A preferred embodiment of the invention is described hereinafter with reference to the drawings, in which:
FIG. 1 is a schematic block diagram illustrating a placement machine having an apparatus in accordance with a preferred embodiment of the invention;
FIG. 2 is plan view of an illustrative example of a reference component substrate for the apparatus of FIG. 1;
FIG. 3 shows circuit schematic of a comparator of the apparatus of FIG. 1 and two axially leaded circuit components and a power supply coupled to the comparator;
FIGs. 4a and 4b are, respectively, a plan view and a side view of an illustrative example of a test jig for the apparatus of FIG. 1;
FIG. 5 is a flowchart illustrating a method for verifying axially leaded circuit components using the apparatus of FIG. 1; and
FIG. 6 is a block diagram of a computer system capable of implementing the method of FIG. 5.
Detailed Description
An apparatus, a method and a computer program product for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine are described. In the following, numerous details are provided for a more thorough description. It shall be apparent to one skilled in the art, however, that the invention may be practised without such details. In other instances, well-known details have not been described at length so as not to obscure the invention.
The advantages of the preferred embodiment of the invention are manifold.
One advantage is that axially leaded circuit components are verified offline without stopping placement of other circuit components by the placement machine. This, therefore, reduces downtime of the placement machine of the preferred embodiment.
Another advantage of the preferred embodiment of the invention is that the axially leaded circuit components for replenishing depleted circuit components are verified against reference components using a half- voltage measurement technique. Hence, variations in a manufacturer's specified values for a circuit component as a result of environmental factors affecting the specified values are overcome or at least alleviated.
Yet another advantage of the preferred embodiment of the invention is that the half- voltage measurement technique also overcomes or at least alleviates the limitation of conventional testing in which conditions of probes or the manner in which contact is made by such probes against electrodes of a circuit component causes variations in measurements.
A further advantage of the preferred embodiment of the invention is that circuit components can be more reliably verified without having to rely on colour coding. Hence, those who are colour blind can use the preferred embodiment of the invention to verify circuit components. In addition, associating colour codes to circuit components is unnecessary and verification of such circuit components is therefore simpler.
Referring now to FIG. 1, a schematic block diagram of a placement machine 10 having an apparatus 11 in accordance with a preferred embodiment of the invention is illustrated. The placement machine 10 also includes a controller 12 and component storage locations 13 represented by a single block. The controller 12 monitors placement of such axially leaded circuit components by a placement member 14. These axially leaded circuit components are selected or picked from the component storage locations 13 for placement onto circuit substrates by the controller 12. The component storage locations 13 can be, for example, cassettes in which axially leaded circuit components in a tape-and-reel format are placed. Typically, the axially leaded circuit components are individually discharged from a cartridge (not shown) at an open-ended portion of such cassettes. The cartridge holds one end of a reel of axially leaded circuit components.
The apparatus 11 further includes a controller input port 15 at which control signals from the controller 12 are received, a processor 16 to process such control signals, a reference component substrate 17 mounted with a plurality of reference components and a comparator 18 coupled to the processor 16 and the reference component substrate 17. In addition, the apparatus 11 also includes a display 19 for displaying indication signals associated with the control signals and test ports 20 at which output signals from the comparator are coupled to a test jig 21. The test jig 21 has a conductor 22 to electrically conduct signals via the test port 20.
The plurality of reference components of the reference component substrate 17 is associated with axially leaded circuit components that are required for placement onto the circuit substrates. FIG. 2 is a plan view of an illustrative example of the reference component substrate 17. The reference component substrate 17 includes an interface connector 23 for selectably providing a plurality of connections to the processor 16. A reference component 26 is indicated. Associated with the reference component 26 are two indicia 27,28. These two indicia are labelled '1' and '61 ' respectively and correspond to cassettes of the component storage locations 13. hi this illustrative example, the reference component substrate 17 can be mounted with sixty reference components corresponding to sixty cassettes. However, one hundred and twenty indicia are shown as the placement machine 10 can support more than sixty cassettes and, hence, more than one reference component substrate 17 can be used. Accordingly, different circuit assemblies can be manufactured with the more than one reference component substrate 17 depending on circuit components that are needed for the different circuit assemblies. Referring now to FIG. 3, a circuit schematic of the comparator 18 of the apparatus 11 is shown. The comparator 18 includes a variable resistor 30 and an operational amplifier 31 having two comparator inputs 32,33. The comparator input 32 is connected to an electrode 34 of the variable resistor 30. Another electrode 35 of the variable resistor 30 is connected to a voltage supply 36 for apparatus 11 via node 37. From the test port 20a, the electrode 35 also connects to a signal line 22a of the conductor 22. The signal line 22a connects to a probe 38 of the test jig 21 (not shown).
The comparator input 33 is connected to another signal line 22b via the test port 20b. The signal line 22b connects to a probe 39 of the test jig 21 (not shown). The comparator input 33 is also connected to the interface connector 23 at node 40. The processor 16 controls the interface connector 23 to select one of the plurality of connections to thereby connect to, for example, the reference component 26 of the reference component substrate 17.
When the probes 38,39 respectively contact electrodes 41,42 of an axially leaded circuit component 42, an electrical coupling of the axially leaded circuit component 42 to the reference component 26 is made. Consequently, the axially leaded circuit component 42 forms a voltage divider with the reference component 26 from which the comparator 18 receives voltage signals via the comparator inputs 32,33. The node 40 is common to both the axially leaded circuit component 42 and the reference component 26. As a result of the electrical coupling forming the voltage divider, a voltage signal is derived at the node 40. This voltage signal is provided to the comparator input 33.
At the comparator input 32, a reference voltage signal is derived using the variable resistor 30 coupled to the axially leaded circuit component 42. The voltage supply 36 supplies the necessary voltage to provide both the voltage signal at the comparator input 33 and the reference voltage signal at the comparator input 32. A comparison of the voltage signal and the reference voltage signal is then performed within the operational amplifier 31.
The test jig 21 at which a reel of axially leaded circuit components are received for verification has the test probes 38,39. A plan view and a side view of an illustrative example of the test jig 21 are shown in FIG. 4a and FIG. 4b, respectively. One side 44 of the test jig is indicated in the plan view to provide a reference for the side view.
The test jig 21 also includes three indication outputs 45,46,47 for indicating whether the axially leaded circuit component 42 is acceptable to replenish supply of a depleted axially leaded circuit component for the placement machine 10. The conductor 22 extends from another side 48 of the test jig 21.
Referring now to FIG. 5, a flowchart illustrates a method 50 for verifying axially leaded circuit components using the apparatus 11. The controller 12 generates a component signal when one of the component storage locations 13 is depleted. This component signal is a control signal provided to the controller input 15 and indicates a depleted axially leaded circuit component. Upon this detection at starting step 51, the method 50 continues to step 52 at which the component signal is received by the processor 16 at the controller input port 15. In addition, at step 52, the processor 16 provides at least one indication signal associated with the component signal. The at least one indication signal is provided to the display 19 for displaying, for example, ' 1 ' to indicate that the depleted axially leaded circuit component corresponds to cassette ' 1 ' in the component storage locations 13.
The method 50 then continues to step 53 at which a reference component is identified that is associated with the depleted axially leaded circuit component. Specifically, the identifying step identifies the reference component at location ' 1 ' of the reference component substrate 17. Upon identification of the reference component, the method 50 continues to step 54 at which the processor 16 detects an electrical coupling of one of a plurality of axially leaded circuit components to the reference component. To simplify description of the method 50, the one of a plurality of axially leaded circuit components is referred to as the axially leaded circuit component 42.
It is to be noted that the plurality of axially leaded circuit components is to replenish supply of the depleted axially leaded circuit component of, for example, the cassette '1' of the component storage locations 13. This plurality of axially leaded circuit components is typically provided in a tape-and-reel format with the axially leaded circuit component being one of such circuit components.
Detecting the electrical coupling at step 54 includes detecting that a series connection has been made from the axially leaded circuit component 42 to the reference component. When step 54 is completed, the processor 16 then derives a voltage signal, at step 55. The voltage signal is derived at the node 49 that is common to both the axially leaded circuit component 42 and the reference component. Thereafter, method 50 continues to step 56 at which the processor 16 controls the comparator 18 to perform a comparison of the voltage signal with the reference voltage signal. The voltage signal is provided to the comparator input 32 and the reference voltage signal is provided to the comparator input 33.
In response to the comparing step 56, the processor 16 determines whether to reject the plurality of axially leaded circuit components at decision step 57. This determining step 57 requires setting the variable resistor 30 such that outcome of the comparison can be variably set based on a predetermined tolerance range. The predetermined tolerance range depends on specifications of the plurality of axially leaded circuit components.
Following a 'Yes' from decision step 57, the outcome from comparing is thus within the predetermined tolerance range. Accordingly, the plurahty of axially leaded circuit components is not rejected and the processor 16 then generates a component acceptance signal at step 58. Otherwise, with a 'No' from decision step 57, the outcome from comparing thus exceeds the predetermined tolerance range. Consequently, the processor 16 then generates a component rejection signal at step 59.
The apparatus 11 in the preferred embodiment of the invention can be implemented using a computer program product such as, for example, a computer system 60 as shown in FIG. 6. In particular, the method 50 can be implemented as software, or computer readable program code, executing on the computer system 60.
The computer system 60 includes the controller input 15, the processor 16, the reference component substrate 17, the comparator 18, the display 19, and the test jig 21. In addition, the computer system 60 further includes input devices 61,62. A communication input/output (I/O) signal bus 63 provides for control signals between the processor 16 and the controller 12.
The computer system 60 also includes a memory 64 that may include random access memory (RAM) and read-only memory (ROM), an input/output (I/O) interface 65 and one or more storage devices represented with a single block as a storage device 66. The memory 64 can be used to store the settings for the predetermined tolerance range once such a range is set. A common bus 67 links elements of the computer system 60 to provide data transfers when processing data based on voltage signals.
User input to operate the computer system 60 can be provided by one or more of the input devices 61,62 via the I/O interface 65. For example, a user of the computer system 60 can use a keyboard as the input device 61 and/or a pointing device such as a mouse as the input device 62. The keyboard and the mouse provide input to the computer system 60. The storage device 66 can consist of one or more of the following: a floppy disk, a hard disk drive, a magneto-optical disk drive, CD- ROM, magnetic tape or any other of a number of non- volatile storage devices well known to those skilled in the art. Each of the elements in the computer system 60 is typically connected to other devices via the common bus 67 that in turn can consist of data, address, and control buses.
The method is effected by instructions in the software that are carried out by the computer system 60. Again, the software may be implemented as one or more modules for implementing the method steps. That is, the processor 16 can be a part of a computer readable program code that usually performs a particular function or related functions.
In particular, the software may be stored in a computer readable medium, including the storage device 66. The computer system 60 includes the computer readable medium having such software or program code recorded such that instructions of the software or the program code can be carried out. The use of the computer system 60 preferably effects advantageously the apparatus 11 to verify axially leaded circuit components prior to placement onto circuit substrates by the placement machine 10.
The computer system 60 is simply provided for illustrative purposes only and other configurations can be employed without departing from the scope and spirit of the invention. The foregoing is merely an example of the types of computers or computer systems with which the embodiments of the invention maybe practised. Typically, the method 50 of the embodiments are resident as software or a computer readable program code recorded on a hard disk drive (such as the storage device 66) as the computer readable medium, and read and controlled using the processor 16. Intermediate storage of the program code and media content data and any data fetched from the network may be accomplished using the memory 64, possibly in concert with the storage device 66.
In some instances, the program may be supplied to the user encoded on a
CD-ROM or a floppy disk (both generally depicted by the storage device 66), or alternatively could be read by the user from the network via a modem device connected to the computer system 60. Still further, the computer system 60 can load the software from other computer readable media. This may include magnetic tape, a ROM or integrated circuit, a magneto-optical disk, a radio or infra-red transmission channel between the computer and another device, a computer readable card such as a PCMCIA card, and the Internet and Intranets including email transmissions and information recorded on Internet sites and the like. The foregoing is merely an example of relevant computer readable media. Other computer readable media may be practised without departing from the scope and spirit of the invention.
The placement machine 10 and the apparatus 1 las described in the above preferred embodiment of the invention advantageously overcomes or at least alleviates one or more of the disadvantages of conventional placement machines and conventional methods of verifying axially leaded circuit components prior to placement onto circuit substrates.
h the foregoing description, the apparatus 11, the method 50 and a computer program product such as, for example, the computer system 60 for verifying axially leaded circuit components prior to placement onto circuit substrates by the placement machine 10 in accordance with a preferred embodiment of the invention are described. Although the preferred embodiment is described, it shall be apparent to one skilled in the art in view of this preferred embodiment that numerous changes and/or modifications can be made without departing from the scope and spirit of the invention.

Claims

Claims:
1. An apparatus for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, said apparatus includes:
means for receiving a component signal from a controller of said placement machine, said component signal being indicative of a depleted axially leaded circuit component, said depleted axially leaded circuit component being for placement onto said circuit substrates;
means for identifying a reference component associated with said depleted axially leaded circuit component;
means for detecting an electrical coupling of one of a plurality of axially leaded circuit components to said reference component, said plurality of axially leaded circuit components being to replenish supply of said depleted axially leaded circuit component for said placement;
means for deriving a voltage signal at a node common to both said one of said plurality of axially leaded circuit components and said reference component;
means for comparing said voltage signal with a reference voltage signal;
and
means for determining whether to reject said plurality of axially leaded circuit components in response to a comparison performed by said comparing means.
2. The apparatus as claimed in Claim 1, wherein said receiving means includes means for displaying at least one indication signal, said indication signal being indicative of said depleted axially leaded circuit component.
3. The apparatus as claimed in Claim 1, wherein said detecting means includes means for detecting a connection of said one of said plurality of axially leaded circuit components in series with said reference component.
4. The apparatus as claimed in Claim 1, wherein said deriving means includes means for deriving said reference voltage signal using a variable resistor connected to said one of said plurality of axially leaded circuit components.
5. The apparatus as claimed in Claim 1, wherein said determining means includes- means for generating a component acceptance signal when outcome of said comparing is within a predetermined tolerance range.
6. The apparatus as claimed in Claim 1, wherein said determining means includes means for generating a component rejection signal when outcome of said comparing exceeds a predetermined tolerance range.
. A method for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, said method including the steps of:
receiving a component signal from a controller of said placement machine, said component signal being indicative of a depleted axially leaded circuit component, said depleted axially leaded circuit component being for placement onto said circuit substrates;
identifying a reference component associated with said depleted axially leaded circuit component;
detecting an electrical coupling of one of a plurality of axially leaded circuit components to said reference component, said plurality of axially leaded circuit components being to replenish supply of said depleted axially leaded circuit component for said placement;
deriving a voltage signal at a node common to both said one of said plurality of axially leaded circuit components and said reference component;
comparing said voltage signal with a reference voltage signal;
and
determining whether to rej ect said plurality of axially leaded circuit components in response to said comparing step.
8. The method as claimed in Claim 1, wherein said receiving step includes the step of displaying at least one indication signal, said indication signal being indicative of said depleted axially leaded circuit component.
9. The method as claimed in Claim 7, wherein said detecting step includes the step of detecting a connection of said one of said plurality of axially leaded circuit components in series with said reference component.
10. The method as claimed in Claim 7, wherein said deriving step includes the step of deriving said reference voltage signal using a variable resistor connected to said one of said plurality of axially leaded circuit components.
11. The method as claimed in Claim 7, wherein said determining step includes the step of generating a component acceptance signal when outcome of said comparing step is within a predetermined tolerance range.
12. The method as claimed in Claim 7, wherein said determining step includes the step of generating a component rejection signal when outcome of said comparing exceeds a predetermined tolerance range.
3. A computer program product with a computer usable medium having a computer readable program code means embodied therein for verifying axially leaded circuit components prior to placement onto circuit substrates by a placement machine, said computer program product including: computer readable program code means for receiving a component signal from a controller of said placement machine, said component signal being indicative of a depleted axially leaded circuit component, said depleted axially leaded circuit component being for placement onto said circuit substrates;
computer readable program code means for identifying a reference component associated with said depleted axially leaded circuit component;
computer readable program code means for detecting an electrical coupling of one of a plurality of axially leaded circuit components to said reference component, said plurality of axially leaded circuit components being to replenish supply of said depleted axially leaded circuit component for said placement;
computer readable program code means for deriving a voltage signal at a node common to both said one of said plurality of axially leaded circuit components and said reference component;
computer readable program code means for comparing said voltage signal with a reference voltage signal;
and
computer readable program code means for determining whether to rej ect said plurality of axially leaded circuit components in response to a comparison performed by said computer readable program code means for comparing.
14. The computer program product as claimed in Claim 13, wherein said computer readable program code means for receiving includes computer readable program code means for displaying at least one indication signal, said indication signal being indicative of said depleted axially leaded circuit component.
15. The computer program product as claimed in Claim 13 , wherein said computer readable program code means for detecting includes computer readable program code means for detecting a connection of said one of said plurality of axially leaded circuit components in series with said reference component.
16. The computer program product as claimed in Claim 13, wherein said computer readable program code means for deriving includes computer readable program code means for deriving said reference voltage signal using a variable resistor connected to said one of said plurality of axially leaded circuit components.
17. The computer program product as claimed in Claim 13, wherein said computer readable program code means for determining includes computer readable program code means for generating a component acceptance signal when outcome of said comparing is within a predetermined tolerance range.
18. The computer program product as claimed in Claim 13, wherein said computer readable program code means for determining includes computer readable program code means for generating a component rejection signal when outcome of said comparing exceeds a predetermined tolerance range.
PCT/SG2000/000071 2000-05-17 2000-05-17 Apparatus and method for verifying axially leaded circuit components WO2001089279A1 (en)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
US4119206A (en) * 1977-05-13 1978-10-10 Usm Corporation Component sequence verifier
SU1305855A1 (en) * 1985-02-12 1987-04-23 Предприятие П/Я В-2974 Converter of resistive bridge disbalance to time interval
US4667403A (en) * 1984-05-16 1987-05-26 Siemens Aktiengesellschaft Method for manufacturing electronic card modules
US5325305A (en) * 1992-07-24 1994-06-28 The Boeing Company Automated setup verification system
US5562384A (en) * 1991-12-23 1996-10-08 Joseph Alvite Tape packaging system with removeable covers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4119206A (en) * 1977-05-13 1978-10-10 Usm Corporation Component sequence verifier
US4667403A (en) * 1984-05-16 1987-05-26 Siemens Aktiengesellschaft Method for manufacturing electronic card modules
SU1305855A1 (en) * 1985-02-12 1987-04-23 Предприятие П/Я В-2974 Converter of resistive bridge disbalance to time interval
US5562384A (en) * 1991-12-23 1996-10-08 Joseph Alvite Tape packaging system with removeable covers
US5325305A (en) * 1992-07-24 1994-06-28 The Boeing Company Automated setup verification system

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