Welding spot and breakpoint position testing system and method based on passive test

Abstract

The invention discloses a passive test-based welding spot breakpoint position test system and method, and belongs to the technical field of printed circuit board welding spot test. The invention provides a passive test-based welding spot and breakpoint position test system. The passive test-based welding spot and breakpoint position test system comprises passive test equipment, a test probe and a printed circuit board, the reflection time is obtained through the passive test equipment, the wire length of the printed circuit board before and after the reliability test is executed is calculated, and the test of the breakpoint position of the welding spot is completed by comparing the wire length. On the basis that the appearance, layout and wiring of a test module of the printed circuit board are not changed, a passive test point is added for each welding spot, precise nondestructive testing of an elastic period can be carried out on the welding spot, a fracture position can be accurately positioned, and the method has a wide application scene in the welding spot reliability test and test field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printed circuit board solder joint testing, in particular to a solder joint breakpoint position testing system and method based on passive testing. BACKGROUND

[0002] Increasing the testing of solder joint breakpoint positions in solder joint reliability testing is a common technique for improving test efficiency, reducing test cycle, and enhancing test coverage, and is commonly used in the field of component selection and design for aviation, aerospace, and marine products.

[0003] Current methods for increasing the testing of solder joint breakpoint positions in solder joint reliability testing include: 1. Using fixed test nodes to perform metallographic sectioning on printed circuit board samples, although this method provides more intuitive test results, it is an irreversible and destructive test that requires the preparation of more printed circuit board samples for comparison, and is costly. 2. In the case of a printed circuit board chip meeting the requirements, a daisy chain method can be used, which uses a chip with daisy chain testing function, installs a special printed board for auxiliary testing circuit design, and measures the resistance value of the chip in real time during the test to obtain the data of the breakpoint position when the solder joint breaks, but this method has high requirements for the module design of the test printed circuit board and is not universal. 3. Using X-ray, CT, and other non-destructive testing methods to periodically perform non-destructive testing such as X-ray and CT during the test, although this method has no special requirements for the module design of the printed circuit board and the function of the chip, but the image judgment lacks decisive quantitative data and cannot be used as a basis for determining the timing of solder joint breakage.

[0004] Therefore, how to provide a testing system with high universality, low cost, and accurate breakpoint position determination has become a technical problem to be solved by those skilled in the art. SUMMARY

[0005] The present application aims to provide a solder joint breakpoint position testing system and method based on passive testing to overcome the limitations of existing technology in testing solder joint breakpoint positions.

[0006] The present application solves the above technical problems by the following technical solutions: The present application provides a solder joint breakpoint position testing system based on passive testing, comprising a passive testing device, a test probe, and a printed circuit board. The first end of the conductor of the printed circuit board is provided with a solder joint to be tested, and the second end of the conductor of the printed circuit board is provided with a solder mask window. The passive testing device is electrically connected to the test probe through a cable, and the distal end of the test probe is connected to the second end of the conductor of the printed circuit board through the solder mask window.

[0007] The further improvement of the present application is that the passive test device adopts a vector network analyzer with a model of PROSUND SP826L.

[0008] The further improvement of the present application is that the material of the test probe is gold platinum tungsten alloy, the reflection coefficient is within ±10%, the transmission attenuation is within ±0.6dB, and the transmission phase shift is ≤2°.

[0009] The further improvement of the present application is that the test probe and the printed circuit board are fixed by the clamping device during the test.

[0010] The further improvement of the present application is that the conductor of the printed circuit board is copper material.

[0011] The present application also provides a method for testing the position of a solder joint breakpoint based on passive test, which comprises the following steps: Step one, obtaining a printed circuit board without performing reliability test, testing the to-be-tested solder joint by the passive test device to obtain a first reflection time, obtaining the transmission speed of the electric signal in the conductor of the printed circuit board, and combining the first reflection time to calculate a first line length A; Step two, performing reliability test on the printed circuit board to obtain a printed circuit board after performing reliability test, testing the to-be-tested solder joint on the printed circuit board after performing reliability test by the passive test device to obtain a second reflection time, and calculating a second line length B according to the transmission speed of the electric signal in the conductor of the printed circuit board and the second reflection time; Step three, judging whether the first line length A and the second line length B are equal, if yes, the solder joint of the printed circuit board does not have breakpoint, and if no, obtaining the engineering file of the printed circuit board and determining the position of the solder joint breakpoint according to the second line length B.

[0012] The further improvement of the present application is that the reliability test comprises temperature cycle test, vibration test and drop test.

[0013] The further improvement of the present application is that the transmission speed of the electric signal in the conductor of the printed circuit board is obtained, and the first line length A is calculated by combining the first reflection time.

[0014] Wherein, L is the value of the first line length A, t is the first reflection time, and v is the transmission speed of the electric signal in the conductor of the printed circuit board.

[0015] The further improvement of the present application is that the engineering file of the printed circuit board is obtained, and the position of the solder joint breakpoint is determined according to the second line length B. The engineering file includes conductor length of the printed circuit board, solder joint height, conductor length in the chip substrate and bonding wire length, when the second line length B and the PCB conductor length are within ±0.2mm, the breakpoint of the solder joint is on the PCB side of the printed circuit board; when the second line length B and the PCB conductor length + solder joint height are within ±0.2mm, the breakpoint of the solder joint is on the chip side of the printed circuit board; when the second line length B and the PCB conductor length + solder joint height + conductor length in the chip substrate are within ±0.2mm, the breakpoint of the solder joint is on the outer bonding point; when the second line length B and the PCB conductor length + solder joint height + conductor length in the chip substrate + bonding wire length are within ±0.2mm, the breakpoint of the solder joint is on the inner bonding point.

[0016] Further improvement of the present application is that when the conductor of the printed circuit board is copper material, the transmission speed v of the electric signal in the conductor of the printed circuit board is 6.6 mil / ps.

[0017] Compared with the prior art, the positive progress effect of the present application is that: The solder joint breakpoint position test system based on passive test provided by the present application includes a passive test device, a test probe and a printed circuit board; the reflection time is obtained through the passive test device, the line length of the printed circuit board before and after the execution of the reliability test is calculated, and the test of the solder joint breakpoint position is completed through comparison of the line length. The present application can increase the passive test point for each solder joint without changing the appearance, layout and wiring of the test module of the printed circuit board, can perform precise non-destructive test on the solder joint in an elastic cycle and accurately locate the fracture position, and has a wide application scenario in the field of solder joint reliability test and test. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application.

[0019] Figure 1 It is a connection schematic diagram of the solder joint breakpoint position test system based on passive test of the present application.

[0020] Figure 2 It is a passive test device test result schematic diagram in the second embodiment of the present application.

[0021] Figure 3 It is a passive test device test result schematic diagram in the third embodiment of the present application. DETAILED DESCRIPTION

[0022] In the following certain exemplary embodiments are simply described. As will be realized by those skilled in the art, the described embodiments can be modified in various different ways without departing from the spirit or scope thereof. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature rather than restrictive.

[0023] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like are based on the orientations or positional relationships shown in the drawings, and are merely intended to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0025] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, or communication; can be directly connected, or indirectly connected through intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0027] It should be understood that the terms "comprises" and "comprising" when used in this specification and the following claims, indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0028] It should also be understood that the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0029] It should further be understood that the term "and / or" as used in the specification and in the claims, if any, means any one of the items, any combination of the items, or all of the items with reference to which that term is used. For example, the phrase "A / B" (where A and B represent items) is intended to encompass A alone, B alone, A and B together, or any combination of A and B.

[0030] Various structural diagrams according to the disclosed embodiments of the application are shown in the accompanying drawings. These diagrams are not drawn to scale, in which certain details are shown in a somewhat exaggerated manner for the purpose of clarity and understanding, and certain details can be omitted. The shapes and relative sizes of the various regions, layers, and their relative positions shown in the drawings are merely exemplary, and in actuality can be deviated due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, and relative positions can be additionally designed by those skilled in the art according to actual needs.

[0031] The application is further described in detail below with reference to the accompanying drawings and specific embodiments. The following description is explanatory only and not intended to be limiting of the application.

[0032] Referring to Figure 1 A solder joint break position testing system based on passive testing, comprising a passive testing device, a test probe, and a printed circuit board; A first end of a conductor of the printed circuit board is provided with a solder joint to be tested, and a second end of the conductor of the printed circuit board is provided with a solder resist window. The passive testing device is electrically connected to the test probe through a cable, and the end of the test probe passes through the solder resist window to connect the second end of the conductor of the printed circuit board.

[0033] The application provides a solder joint break point position test system based on passive testing, which comprises a passive test device, a test probe and a printed circuit board. The application can increase passive test points for each solder joint without changing the appearance, layout and wiring of a test module of the printed circuit board, can perform precise non-destructive test and accurately locate the break point of the solder joint in an elastic cycle, has a wide application scenario in the field of solder joint reliability test and test, can increase passive test points without changing the appearance, layout and wiring of the solder joint reliability test module, and can perform non-destructive test in an elastic cycle, that is, when it is necessary to increase the test frequency, the test frequency can be increased without increasing the test sample to achieve the purpose.

[0034] Preferably, the passive test device is a vector network analyzer with a model number of PROSUND SP826L.

[0035] Preferably, the test probe is made of gold platinum tungsten alloy, the reflection coefficient is within ±10%, the transmission attenuation is within ±0.6 dB, and the transmission phase shift is less than or equal to 2°.

[0036] Preferably, the test system further comprises a clamping device, and the test probe and the printed circuit board are fixed by the clamping device during test.

[0037] Preferably, the conductor of the printed circuit board is made of copper.

[0038] Based on the same inventive concept, the application further provides a method for testing the break point position of a solder joint based on passive testing. Step one, obtaining a printed circuit board without performing a reliability test, testing a to-be-tested solder joint of the printed circuit board by using the passive test device to obtain a first reflection time; obtaining a transmission speed of an electric signal in a conductor of the printed circuit board, and combining the first reflection time to calculate a first line length A; Step two, performing a reliability test on the printed circuit board to obtain a printed circuit board having performed a reliability test, testing a to-be-tested solder joint on the printed circuit board having performed the reliability test by using the passive test device to obtain a second reflection time; according to the transmission speed of the electric signal in the conductor of the printed circuit board and the second reflection time, calculating a second line length B; Step three, judging whether the first line length A and the second line length B are equal, if yes, the solder joint of the printed circuit board does not exist a breakpoint; if no, obtaining the engineering file of the printed circuit board, and determining the solder joint breakpoint position according to the second line length B.

[0039] Preferably, the reliability test includes temperature cycle test, vibration test and drop test.

[0040] Preferably, the transmission speed of the electrical signal in the conductor of the printed circuit board is obtained, and the first line length A is calculated according to the first reflection time.

[0041] Wherein, L is the value of the first line length A; t is the first reflection time; v is the transmission speed of the electrical signal in the conductor of the printed circuit board.

[0042] Preferably, the engineering file of the printed circuit board is obtained, and the solder joint breakpoint position is determined according to the second line length B. The engineering file includes the conductor length of the printed circuit board, the solder joint height, the conductor length of the substrate in the chip and the length of the bonding wire. When the second line length B and the PCB conductor length differ by ±0.2mm, the breakpoint position of the solder joint is on the PCB side of the printed circuit board; when the second line length B and the PCB conductor length + solder joint height differ by ±0.2mm, the breakpoint position of the solder joint is on the chip side of the printed circuit board; when the second line length B and the PCB conductor length + solder joint height + conductor length of the substrate in the chip differ by ±0.2mm, the breakpoint position of the solder joint is on the outer bonding point; when the second line length B and the PCB conductor length + solder joint height + conductor length of the substrate in the chip + length of the bonding wire differ by ±0.2mm, the breakpoint position of the solder joint is on the inner bonding point.

[0043] Preferably, when the conductor of the printed circuit board is copper material, the transmission speed v of the electrical signal in the conductor of the printed circuit board is 6.6 mil / ps.

[0044] Example one Add independent test points for each pin of the measured chip on the printed circuit board to be tested, and set a solder mask window at the position of the test points; build a test environment through a tooling fixture, a general passive device, and a test module (PCB) after assembly; calculate the original length by calibrating the initial value of the passive test; measure the length of the wire again after the environmental test scheme is sent for testing; if the length of the test result changes from the original length, the breakpoint position can be calculated. The application can ensure that the passive test points are added without changing the appearance, layout, and wiring of the solder joint reliability life test module, and can perform elastic period non-destructive testing. That is, when the test frequency needs to be increased, the test sample can be tested without increasing the test frequency. Further, the application can solve the problems of limited test cost and period, test piece design versatility, active test risk, and insufficient accessibility, etc.

[0045] The embodiment introduces passive test points for each solder joint without changing the original module appearance, layout, and wiring, and performs solder mask windowing, so that it has the function of connecting general passive test tools. The original length is calculated by calibrating the initial value of the passive test. The length of the through hole and the wire on the PCB + the length of the solder joint / lead + the length of the bonding wire inside the device is measured under the non-destructive premise of the tested module using the general passive test tool, so that the test data can cover the accurate length of the complete conductor from the test point to the chip inside. The length of the complete conductor from the test point to the chip inside is measured again after the printed circuit board is sent for testing using the passive test environment, so that the general passive test tool is used to measure the tested module again under the original calibration environment after the test, and the accurate length of the complete conductor from the test point to the chip inside after each test is obtained, so that it has the function of recording the length data of each solder joint, the conductor inside the chip, and the PCB conductor. The breakpoint position is calculated, and the difference between the test length and the calibration length is determined by using the micron-level precision measurement feature of the passive test tool, and then the de-energized position on the PCB side, the chip side, the external bonding point, and the internal bonding point are calculated by combining the length of the conductor inside the PCB and the length of the bonding wire in the engineering file.

[0046] The application has the characteristics of strong economy, high precision, high flexibility of test design, short test period, and simple test piece design. The non-destructive test is realized by periodically measuring the passive length of the test piece and comparing the calibration value by quantitative test means. The application can be used for solder joint life test and analysis of integrated circuits with solder joint life test requirements, such as ceramic BGA, large-size plastic BGA, high-reliability QFN / QFP / LCC, etc.

[0047] Embodiment two Step 1: Design the logic diagram and PCB layout of the PCB of the module under test to add test points, and implement the passive test point layout without changing its basic functional performance.

[0048] Step 2: Design the tooling and experiments for the module under test, and set up the test environment.

[0049] Step 3: PCB and component production.

[0050] Step 4: PCBA assembly.

[0051] Step 5: Perform passive conductor length calibration test on the module under test: Since the formula for calculating the conductor length is...

[0052] By identification Figure 2 The first maximum inflection point is the echo reflection time. The unimpeded test reflection time is t=64.875ps. The transmission speed of the electrical signal in the conductor is v=6.6mil / ps, then L=214.8075mil≈5.438mm.

[0053] Step 6: Perform 100 temperature cycles of -55℃ to 125℃ on the module under test according to the reliability test requirements.

[0054] Example 3 The difference from Example 2 is that: Step 5: Perform a passive conductor length test on the module under test: Since the formula for calculating the conductor length is...

[0055] By identification Figure 3 The first maximum inflection point is the echo reflection time. The unimpeded test reflection time is t=37.722ps. Taking the transmission speed of the electrical signal in the conductor as v=6.6 mil / ps, then L=124.4826mil≈3.162mm.

[0056] Since the test points and test environment of Example 2 and Example 3 are the same, the difference is that the module has undergone 100 temperature cycles of -55℃ to 125℃. According to the printed circuit board design line length of 3mm, the electrical connection on this path after the temperature cycle was broken during the second measurement, and the break point was on the solder ball.

[0057] The method of this invention performs passive line length measurement and calibration value comparison on the test piece at regular intervals, and achieves non-destructive testing through quantitative testing. It can be used for solder joint life testing and analysis of integrated circuits with solder joint life testing requirements, such as ceramic-encapsulated BGA, large-size plastic-encapsulated BGA, and high-reliability QFN / QFP / LCC.

[0058] Finally, it should be noted that the above examples are only one or more specific forms of the present application, and their purpose is to clearly illustrate the concept, principle and application of the present application through specific examples, and are not intended to limit the scope of protection of the present application to these specific examples. In fact, the true value of the present application lies in its proposed technical ideas and innovative points, not in its forms or means of implementation.

[0059] For those skilled in the art, after reading and understanding the technical solutions of the present application, they have the ability to make various forms of changes, modifications or equivalent replacements to the specific embodiments of the application based on their own professional knowledge and skills. These changes may include but are not limited to adjusting the value range of technical parameters, optimizing the algorithm process to improve efficiency, replacing part of the technical components to achieve better compatibility or reduce cost, etc. As long as the technical solutions after these changes still maintain the technical features required by the original application, that is, still can realize the core function and effect of the present application, these changes should be considered as falling within the scope of protection of the claims of the present application.

[0060] In addition, with the continuous progress and development of technology, new technical means and methods are emerging, which also provides a broad space for the further improvement and perfection of the present application. Therefore, the scope of protection of the present application should also include those reasonable foreseeable improvements and extensions based on the existing technology, as long as these improvements and extensions do not deviate from the basic principles and core concept of the present application, they should be considered as the equivalent of the present application, and also be protected by the patent right.

Claims

1. A passive test based solder joint break point location test system, characterized by, The application relates to a passive test device, a test probe and a printed circuit board. The first end of the conductor of the printed circuit board is provided with a to-be-tested soldering point, and the second end of the conductor of the printed circuit board is provided with a solder mask window; the passive test device is electrically connected to the test probe through a cable; and the tail end of the test probe is connected to the second end of the conductor of the printed circuit board through the solder mask window.

2. The passive test based solder joint break location test system of claim 1, wherein, The passive test device is a vector network analyzer with a model number of PROSUND SP826L.

3. The passive test based solder joint break location test system of claim 1, wherein, The material of the test probe is gold platinum tungsten alloy, the reflection coefficient is within + / -10%, the transmission attenuation is within + / -0.6dB, and the transmission phase shift is less than or equal to 2 degrees.

4. The passive test based solder joint break location test system of claim 1, wherein, The application further comprises a clamping device, which is used to fix the test probe and the printed circuit board during testing.

5. The passive test based solder joint break location test system of claim 1, wherein, The conductor of the printed circuit board is made of copper.

6. A method of testing a location of a break in a solder joint based on passive testing as claimed in any one of claims 1 to 4, wherein, The application comprises the following steps: Step one: obtaining a printed circuit board which has not been tested for reliability, testing the to-be-tested soldering point through the passive test device to obtain a first reflection time; obtaining the transmission speed of an electric signal in the conductor of the printed circuit board, and combining the first reflection time to calculate a first line length A; Step two: performing a reliability test on the printed circuit board to obtain a printed circuit board which has been tested for reliability, testing the to-be-tested soldering point on the printed circuit board which has been tested for reliability through the passive test device to obtain a second reflection time; and according to the transmission speed of the electric signal in the conductor of the printed circuit board and the second reflection time, calculating a second line length B; Step three: judging whether the first line length A and the second line length B are equal; if yes, the soldering point of the printed circuit board does not have a breakpoint; If no, obtaining the engineering file of the printed circuit board, and determining the soldering point breakpoint position according to the second line length B.

7. The method of passive test based solder joint break point location testing system of claim 6, wherein, The reliability test comprises a temperature cycle test, a vibration test and a drop test.

8. The method of passive test based solder joint break point location testing system of claim 6, wherein, The transmission speed of the electric signal in the conductor of the printed circuit board is obtained, and the first line length A is calculated by combining the first reflection time. Wherein, L is the value of the first line length A; t is the first reflection time; and v is the transmission speed of the electric signal in the conductor of the printed circuit board.

9. The method of passive test based solder joint break point location testing system of claim 6, wherein, The engineering file of the printed circuit board is obtained, and the soldering point breakpoint position is determined according to the second line length B. The engineering file comprises the conductor length of the printed circuit board, the soldering point height, the conductor length of the substrate in the chip and the length of the bonding wire; when the second line length B and the PCB conductor length differ by less than or equal to + / -0.2mm, the soldering point breakpoint position is on the PCB side of the printed circuit board; when the second line length B and the PCB conductor length + the soldering point height differ by less than or equal to + / -0.2mm, the soldering point breakpoint position is on the chip side of the printed circuit board; when the second line length B and the PCB conductor length + the soldering point height + the conductor length of the substrate in the chip differ by less than or equal to + / -0.2mm, the soldering point breakpoint position is on the outer bonding point; and when the second line length B and the PCB conductor length + the soldering point height + the conductor length of the substrate in the chip + the length of the bonding wire differ by less than or equal to + / -0.2mm, the soldering point breakpoint position is on the inner bonding point.

10. The method of passive test based solder joint break point location test system of claim 8, wherein, When the conductor of the printed circuit board is made of copper, the transmission speed v of the electric signal in the conductor of the printed circuit board is 6.6 mil / ps.

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