JP2011007754A - Testing method of circuit board, and test system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a testing method and its system for accurately measuring electric characteristics of a circuit board which is heated or cooled in advance, with no inspecting device side affected by heat, for environmental test and the like.SOLUTION: The circuit board 2 which is heated or cooled in advance for environmental test and the like is carried into a test station. It is made to electrically contact to a test tool 12 which is installed on the test station, and then electric characteristic of the circuit board 2 is measured using an inspecting device 15 connected to the test tool 12 by a cable 14. During the test process, the cable 14 is thermally controlled by a thermal control device 16, so that the heat on the circuit board 2 side is prevented from transferred to the inspecting device 15 through the cable 14.

Description

  The present invention relates to a method for testing a circuit board for forcibly heating and cooling a circuit board for environmental tests and the like to determine whether the circuit board is good or bad under the condition, and a test system therefor.

Defects in circuit boards used in various electrical equipment include bonding defects such as mouse bites (pattern chipping), laser vias, blind vias, and solder defects, and such defects often do not appear in normal temperature environments. It is difficult to detect in a normal test.
Therefore, the current situation is to prevent the trouble after shipment as much as possible by putting the finished product of the electronic device into the environmental testing machine and performing the aging inspection (stress test).

  In Patent Document 1, as a technique for detecting a potential defect such as a fine portion (a narrowed portion or a crack) of a circuit board, a test current in which a direct current and an alternating current are superimposed is passed through a circuit to be inspected. The second harmonic of the test current caused by the temperature cycle of heating and cooling due to the Joule heat generated in Fig. 1 is described.

  Patent Document 2 discloses, as a technique further improving Patent Document 1, a first DC power supply, a second DC power supply, an AC power supply, and a first probe set that forms a pair for connection to both ends of a circuit to be inspected. And a switch for switching and connecting the AC power source to the first probe set or the second probe set, and the switch switches preheating and inspection between a plurality of circuits to be inspected. It is described that the entire inspection time is shortened by performing preheating in parallel.

JP-A-58-19173 JP 2005-300386 A

  However, in the method of manufacturing a finished product by incorporating a circuit board into the electronic device described above and then putting the finished product into an environmental testing machine and performing an aging inspection, if the circuit board is defective, the finished product is disassembled. However, it is expensive and troublesome.

  Therefore, it is desired to detect a defect in the previous stage of incorporation as a finished product, that is, the circuit board as it is, but in the current method, when the circuit board is heated and tested, the circuit board becomes a heat source, In addition to affecting the test results, in some cases, the cable connecting the test jig connected to the circuit board and the inspection device will burn out, or heat will be conducted through the cable to the inspection device. Thus, problems such as damage to the electronic circuit in the inspection apparatus remain unsolved. In particular, for products that are used in automobiles and that are subjected to severe environmental temperatures during operation, it is necessary to set the temperature applied to the circuit board in the same way, and the test must be performed. The problem becomes even more pronounced.

  On the other hand, in the techniques disclosed in Patent Documents 1 and 2, although it is possible to heat the circuit pattern with Joule heat by passing an electric current through the circuit board, depending on the circuit configuration, such a current for heating is used. In some cases, it is unacceptable to flow, and in the method of heating a circuit board by energization, conditions for cold regions cannot be set, and it is far from the actual conditions of use, and all circuit board usage conditions are assumed. It ’s hard to be an exam.

  Therefore, the present invention, regardless of the circuit configuration of the circuit board, gives the circuit board a severe temperature condition assuming the use state, and then examines the electrical characteristics at that time, thereby determining whether the circuit board is good or defective. It is an object of the present invention to provide a method and a system capable of discriminating the above.

  In the circuit board testing method according to the present invention, a circuit board that has been heated or cooled in advance for testing is brought into a test station, and electrically contacted with a test jig installed in the test station. A circuit board test method for measuring electrical characteristics of the circuit board by an inspection device connected to a test jig through a cable, wherein the cable is thermally controlled so that the heat on the circuit board side is the cable. It is characterized in that conduction to the inspection device is prevented.

  Here, the circuit board includes all kinds of circuit boards such as a printed board, a flexible board, a COF (Chip On Film), and a TCP (Chip Carrier Package), and the circuit board includes electronic components such as a semiconductor chip. It may or may not be implemented. In the method of the present invention, the circuit board is directly heated and cooled to measure the electrical characteristics under the environmental conditions to be used, and based on the result, good or bad is discriminated. Examples of the measurement of electrical characteristics here include, for example, energization of a circuit board, short circuit inspection, leak inspection, insulation resistance measurement, resistance measurement (direct current, alternating current), capacitance measurement, and inductance measurement.

  In the circuit board test system according to the present invention, a test station provided with a test jig that is in electrical contact with the circuit board is connected to the test jig through a cable, and the electrical characteristics of the circuit board are measured. An inspection device, and a heat control device that controls heat by heating and cooling the cable, and the circuit board is heated or cooled for testing and is carried into the test station, and the test jig After being in electrical contact, the inspection device measures the electrical characteristics of the circuit board through the cable.

  Here, the test station only needs to be equipped with an inspection jig connected to the inspection apparatus through a cable, and in the middle of the conveyance path for conveying the circuit board, the probe that contacts the corresponding connection terminal of the circuit board is inspected and cured. The structure provided as a tool may be sufficient. The test jig and the inspection device may include a temperature sensor, and the thermal control device may be configured to heat or cool the cable based on a temperature detected by the temperature sensor.

  If the inspection device has a function of being able to measure the electrical specification of the circuit board through electrical contact with the corresponding connection portion of the circuit board through a test jig provided at the end of the cable, a known inspection device is adopted as it is. it can. The thermal control device may be configured to heat or cool the cable based on the temperature detected by the temperature sensor.

  Note that a heat transfer member is added to a portion of the cable that is heated and cooled by the heat control device, and it is preferable that the heat control device heat-controls the cable through the heat transfer member. The heat transfer member is not limited to metal, but a material having high thermal conductivity is desired.

  The cable may be a flat cable. Specific examples of the flat cable include a flat cable and a flexible cable.

  Alternatively, the cable may be composed of a plurality of single-wire cables. Specific examples of the single wire cable include an enamel wire and a magnet wire.

  In the circuit board test method and test system according to the present invention, the cable is thermally controlled, and the circuit board serves as a heat source to prevent the heat from being transmitted to the cable through the test jig. It is possible to reliably prevent the coating from being melted and the cable connector and electronic circuit in the inspection apparatus from being burned out. Therefore, it becomes possible to test a plurality of circuit boards continuously by batch processing without being influenced by heat.

  Moreover, in the structure which added the heat-transfer member to the intermediate part heated and cooled of a cable, since the thermal control of the cable by a thermal control apparatus is performed efficiently, the power consumption of a thermal control apparatus is suppressed.

  In the configuration in which the temperature sensor is provided in the test jig or inspection device, the thermal control device can control the cable more precisely.

FIG. 1 is an overall system diagram of an embodiment. These are the partial system diagrams which showed the principal part structure of the Example. (A) is a perspective view of the cable which added the heat-transfer member, (b) is a longitudinal cross-sectional view of the cable made into the multilayer structure.

FIG. 1 shows the overall configuration of a circuit board test system according to the present invention.
The test system 1 is electrically connected to a first thermal control device 11 that preheats or cools a circuit board 2 to be tested to a predetermined temperature, and a predetermined point on the circuit board 2 that is carried in from the first thermal control device 11. A test station in which the test jig 12 in contact is installed, a second thermal control device 13 that cools or heats the circuit board 2 after the test to return to room temperature, and the test jig 12 are connected by a cable 14. An inspection device 15 that tests the electrical characteristics of the test board via the test jig 12 and the cable 14, and a third heat control device 16 that controls the intermediate portion of the cable 14 are provided. The first and second thermal control devices 11 and 13 and the test station are connected by a conveying means 17 that automatically conveys the circuit board 2. The test station means a place where the test jig 12 is installed, and a probe that contacts a corresponding connection terminal of the circuit board is provided as an inspection jig in the middle of the conveyance path for conveying the circuit board. The configuration is also included.

  As the circuit board 2 to be tested, all kinds of circuit boards such as a printed board, a flexible board, a COF (Chip On Film), and a TCP (Chip Carrier Package) can be considered. These can be a test object whether or not an electronic component such as a semiconductor chip is mounted.

  FIG. 2 is a diagram specifically showing the test jig 12, the inspection device 15, and the third heat control device 16 installed in the test station in the test system 1. On the upper surface of the test jig 12, a plurality of probe pins 12a are arranged in a pattern corresponding to the circuit board 2. When the circuit board 2 is placed on the test jig 12, each probe pin 12a is The test lands on the circuit board 2 are brought into contact with each other. Each probe pin 12a has its own elasticity or is urged upward by a metal spring or the like, and presses the circuit board 2 placed on the test jig 12 downward. Then, the circuit board 2 is electrically connected to the target connection terminal, the test land, or the like. Moreover, there is no restriction | limiting in the number of probe pins 12a.

  The probe pin 12a is connected to a connector provided on the test jig 12, and a cable 14 led out from the inspection apparatus is connected to this connector. The type of the cable 14 is not particularly limited. For example, the cable 14 may be composed of a general-purpose flat cable or a flexible cable, or may be composed of a harness composed of a single wire cable such as an enamel wire or a magnet wire.

  The cable 14 is connected to the inspection device 15 via the third heat control device 16. A heat transfer member 18 having excellent heat conductivity is added to an intermediate portion of the cable 14 that is heated and cooled by the heat control device 16, and the heat control device 16 controls the cable 14 through the heat transfer member 18. To do. The heat transfer member 18 may be formed of, for example, a copper plate or an aluminum plate. In this way, if the heat transfer member 18 is added to the portion of the cable 14 to be heated and cooled, the heat control of the cable 14 by the third heat control device 16 is performed efficiently, so that the power consumption can be suppressed. .

  As the electrical characteristics of the circuit board 2, the inspection device 15 performs, for example, an energization inspection, a leakage inspection, an insulation resistance measurement, a resistance measurement (DC, AC), a capacitance measurement, an inductance measurement, and the like. Although it is desired to have a function of discriminating a defect, a conventional inspection apparatus may be used as it is.

  FIG. 3A is a perspective view of the cable to which the heat transfer member 18 is added, and FIG. 3B is a longitudinal cut view of the cable having a multilayer structure. In the example of FIG. 3A, the cable 14 is sandwiched from both sides by a heat transfer member 18 made of a copper plate. On the other hand, in the example of FIG. 3B, there are a large number of cables 14 and a multilayer structure in which the heat transfer member 18 made of a copper plate and the cable 14 are overlapped with each other. Of course, in this case, it is important that the outermost side is a copper plate.

  The portion of the cable 14 to which the heat transfer member 18 is added is thermally controlled by the third heat control device 16. Although there is no special restriction | limiting in the classification of the 3rd heat control apparatus 16, if the 1st heat control apparatus 11 is a type which heats the circuit board 2, the 3rd heat control apparatus 16 will cool the cable 14 If the first heat control device 11 is a type that cools the circuit board 2, the third heat control device 16 needs a function of heating the cable 14.

  The configurations of the first and second thermal control devices 11 and 13 are not particularly limited, but in terms of capability, the capability of heating and cooling the circuit board 2 in the range of about 160 ° C. to −70 ° C. is desired. This is because the open defects of the circuit board 2 include contact defects such as mouse bites (pattern chipping), laser vias, blind vias, and cracks such as through holes and fine patterns (fine patterns). This is because it is generally necessary to raise the temperature of the circuit board 2 in order to detect it, and it is generally necessary to lower the temperature of the circuit board 2 in order to detect short-circuit defects such as solder jumps.

  Specifically, for example, an environmental tester may be used as the first to third heat control devices 11, 13, and 16. A general environmental testing machine has the performance of thermally controlling a controlled object from a desired temperature to about ± 1 ° C. by generating low-temperature air with a thermostream and generating high-temperature air with a heater.

  Other mechanisms may be used as the first to third heat control devices 11, 13, and 16. For example, as a cooling means, an electromagnetic valve that controls the release of high-pressure carbon dioxide gas is provided in the temperature control chamber and the cable 14 is cooled by gas expansion, and as a heating means, a heater is provided in the temperature control chamber. A mechanism that directly heats the heat transfer member 18 with heat may be considered. Further, a temperature medium flow path may be formed as in a mold temperature controller, and the temperature may be controlled by passing a heated and cooled temperature medium through the flow path.

  Note that the temperature control of the cable 14 by the third thermal control device 16 is because the temperature of the heated or cooled circuit board 2 is constant, and the number of circuit boards 2 to be tested per time is also constant. The third heat control device 16 may be configured to cool or heat the cable 14 at a constant temperature. Needless to say, the third control device 16 has a built-in temperature sensor 19 and has a function of heating or cooling the cable 14 based on the temperature detected by the temperature sensor 19.

  Further, as an improved configuration, the test jig 12 includes a temperature sensor 19 such as a thermistor or a thermocouple, and the third heat control device 16 heats the cable 14 based on the temperature detected by the temperature sensor 19. You may make it cool.

  The inspection device 15 may include a temperature sensor 19, and the third thermal control device 16 may heat or cool the cable 14 based on the temperature detected by the temperature sensor 19. Of course, both the test jig 12 and the inspection device 15 are provided with a temperature sensor 19, and the third thermal control device 16 heats or cools the cable 14 based on the temperature detected by the temperature sensor 19. May be. As described above, in the configuration in which the test jig 12 or the inspection device 15 includes the temperature sensor 19, the third heat control device 16 can control the cable 14 more precisely.

  Next, a test process for the circuit board 2 in the test system 1 according to the present invention will be described. The test system 1 tests the electrical characteristics of the circuit board 2 basically without human intervention by an automatic conveyance system.

  More specifically, the circuit board 2 is carried into the first heat control device 11 by the conveying means 17 and stays in the first heat control device 11 for a predetermined time, whereby it is heated or cooled to a preset temperature. The circuit board 2 heated or cooled here is carried into the test station by the conveying means 17 and placed at a predetermined position on the test jig 12, and is directed from above to the test jig 12 by a press device or the like. Pressed. As a result, the connection terminals and test lands of the circuit board 2 and the probe pins 12 a of the test jig 12 are in electrical contact, and the circuit board 2 is coupled to the inspection device 15. The inspection device 15 measures various electrical characteristics of the circuit board 2 to determine whether the circuit board 2 is good or bad. The determination result is displayed on the display unit of the inspection device 15 and stored in a storage device (not shown). Furthermore, a buzzer or the like may be sounded based on the test result. Moreover, you may control the apparatus (not shown) which performs marking of the discrimination | determination result to the circuit board 2. FIG. When the test is completed, the circuit board 2 on the test jig 12 is carried into the second thermal control device 13 by the conveying means 17 and returned to room temperature there.

  The above test is sequentially performed on a plurality of circuit boards 2 as a batch process. During this time, the third temperature control device monitors the temperature of the test jig 12 or the temperature of the inspection device 15. The cable 14 is cooled or heated so that the temperature falls within a certain range. In the present invention, the circuit board 2 heated or cooled for the test becomes a heat source by such heat control of the cable 14, and the heat is transferred to the cable 14 via the test jig 12, thereby Therefore, it is possible to reliably prevent the insulation coating 14 from being melted and the cable connector and the electronic circuit in the inspection device 15 from being burned out.

  Note that the heat transfer member 18 of the cable 14 may extend to not only the middle portion of the cable 14 but also the test jig 12 and the inspection device 15 as a cable cover and connect to them. In this way, the cable 14 can be more reliably protected from damage due to heat. Further, since the heat control by the third heat control device 16 is also quickly transmitted to the cable connector and the electronic circuit in the inspection device 15, the protection thereof is further ensured.

  When the heat transfer member 18 of the cable 14 is used as a cover as described above, the temperature sensor 19 that measures the temperature of the test jig 12 or the inspection device 15 is attached to the cable cover near the test jig 12 or the inspection device 15. It may be attached.

DESCRIPTION OF SYMBOLS 1 Test system 2 Circuit board 12 Test jig 14 Cable 15 Inspection apparatus 16 Thermal control apparatus 18 Heat transfer member 19 Temperature sensor

Claims (7)

A circuit board that has been heated or cooled in advance for testing is brought into a test station, brought into electrical contact with a test jig installed in the test station, and connected to the test jig through a cable. A circuit board test method for measuring electrical characteristics of the circuit board by an apparatus,
A circuit board testing method characterized in that heat control of the cable prevents the heat on the circuit board side from being conducted to the inspection device via the cable. A test station with a test jig in electrical contact with the circuit board;
An inspection device connected to the test jig through a cable and measuring the electrical characteristics of the circuit board; and a heat control device for controlling heat by heating and cooling the cable,
The circuit board is heated or cooled for a test, is brought into the test station, and is electrically contacted with the test jig. Then, the inspection apparatus passes through the cable to electrically connect the circuit board. A circuit board test system that measures characteristics. In claim 2,
The test jig includes a temperature sensor,
The thermal control device is a circuit board test system that heats or cools the cable based on the temperature detected by the temperature sensor. In claim 2,
The inspection apparatus includes a temperature sensor,
The thermal control device is a circuit board test system that heats or cools the cable based on the temperature detected by the temperature sensor. In any one of Claims 2-4,
The cable has a heat transfer member added to a portion that is heated and cooled by the thermal control device,
The thermal control device is a circuit board test system that thermally controls the cable through the heat transfer member. In any one of Claims 2-5,
The cable is a circuit board test system configured by a flat cable. In any one of Claims 2-5,
The cable is a circuit board test system comprising a plurality of single-wire cables.

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