CAF classification screening method and device

Abstract

The embodiment of the invention relates to a CAF classification screening method and device, and the method comprises the steps: adding a technology edge on a coupon board, the technology edge is provided with a plurality of test regions, and each test region is provided with different HW-IL intervals; and according to the size of the HW-IL spacing, carrying out a step-by-step on-off test on the test area. Graded alignment screening of coupons is achieved, the problem that alignment of CAF HW-IL cannot be accurately and quantitatively monitored is solved, and the strict quality and test requirements of CAF products are met.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of PCB manufacturing, and in particular to a CAF grading and screening method and device. Background Art

[0002] With the vigorous development of new energy vehicles, PCB design has become more sophisticated, and the distance between adjacent metal electrodes has become shorter and shorter. The failure of conductive anodic filament (CAF) leading to internal short circuit in PCB has become a key factor affecting the reliability of automotive electronics.

[0003] IPC-TM-650 hole chain design, CAF test module contains three test channels: HW-HW, HW-IL, and IL-IL. Channel HW-IL is the distance from the drill hole wall to the inner copper layer. Its hole chain contains hundreds or even thousands of holes. The deviation of any hole will lead to a reduction in insulation distance and increase the risk of CAF failure. The conventional HW-IL good product selection method is through ET / horizontal slicing / X-RAY, which has high inspection cost, low efficiency, and cannot quantify CAF alignment deviation. Summary of the invention

[0004] In view of the above problems, the embodiments of the present invention provide a CAF grading screening method and device for solving the existing IPC-TM-650 hole chain design. The CAF test module contains three test channels: HW-HW, HW-IL, and IL-IL. The channel HW-IL is the distance from the drill hole wall to the inner copper layer. The hole chain contains hundreds or even thousands of holes. The deviation of any hole will lead to a reduction in the insulation distance and increase the risk of CAF failure. The conventional HW-IL good product selection method is through ET / horizontal slicing / X-RAY, which has high inspection cost, low efficiency, and cannot quantify the problem of CAF alignment deviation.

[0005] According to one aspect of an embodiment of the present invention, a CAF grading screening method is provided, wherein the method comprises: Adding a process edge on the coupon board, wherein the process edge has a plurality of test areas, each of the test areas having a different HW-IL spacing; According to the size of the HW-IL spacing, the test area is subjected to a step-by-step on-off test.

[0006] In some optional embodiments, the test area includes a first test point and a second test point. When testing the test area, two probes of a multimeter are connected to the first test point and the second test point respectively for testing.

[0007] In some optional embodiments, the first test point is connected to all inner layers, and the first test point is connected to the outer circle PAD of the coupon board, the outer circle PAD has a diameter of 2 mm, and the solder mask window is 0.076 mm.

[0008] In some optional embodiments, the first test point includes an A test point and at least one N test point, wherein the A test point connects all inner layers of the coupon board; and the N test point is from the L(N) inner layer to the outer layer of the coupon board.

[0009] In some optional embodiments, the N test points are inner layer test points of the coupon board that need to be monitored, and the N test points are set according to the number of inner layers of the coupon board that need to be monitored.

[0010] In some optional embodiments, the second test point is connected to all the drill holes, and the second test point is connected to the outer square PAD of the coupon board, the outer square PAD has a size of 6.5*4.5 mm, and the solder mask window has a size of 6.576*4.576 mm.

[0011] In some optional embodiments, the number of test areas is 3, and the 3 test areas are respectively a first test area, a second test area, and a third test area. The HW-IL spacing of the first test area is 50um, the HW-IL spacing of the second test area is 62.5um, and the HW-IL spacing of the third test area is 75um.

[0012] In some optional embodiments, the step-by-step on-off test of the test area according to the size of the HW-IL spacing specifically includes: According to the size of the HW-IL spacing, the test areas are sorted from small to large; First, the first test area is tested for continuity. If the test passes, the current product is a Class A product. If the first test area fails the test, the second test area is tested for continuity. If the test passes, the current product is a Class B product. When the second test area fails the test, the third test area is tested for continuity. If the test passes, the current product is a Class C product. When the third test area fails the test, the current product is a substandard product.

[0013] In some optional embodiments, if the current product is an unqualified product, the abnormal inner layer of the current product is located by respectively measuring the N test points and the second test point in any test area through a multimeter probe, generating abnormal data; and re-making the board according to the abnormal data.

[0014] According to another aspect of an embodiment of the present invention, a CAF grading and screening device is provided, wherein the device is used to execute the above-mentioned CAF grading and screening manufacturing method, and is used to perform continuity testing on products.

[0015] The CAF grading screening method and device of the present invention has the following beneficial effects: the present invention adds a process edge to the coupon board, the process edge has multiple test areas, each of the test areas has a different HW-IL spacing; according to the size of the HW-IL spacing, the test areas are subjected to step-by-step on-off tests. The grading alignment screening of coupons is achieved, the problem that the alignment of CAF HW-IL cannot be accurately quantitatively monitored is solved, and the strict quality and testing requirements of CAF products are met.

[0016] The above description is only an overview of the technical solution of the embodiment of the present invention. In order to more clearly understand the technical means of the embodiment of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings: Figure 1 The figure shows a schematic flow chart of the CAF grading screening method of Example 1 provided by the present invention; Figure 2 The figure shows a schematic flow chart of the CAF grading screening method according to Example 2 provided by the present invention; Figure 3 A schematic diagram showing the HW-IL spacing provided by the present invention is shown.

[0018] Figure 4 A schematic diagram of a coupon board provided by the present invention is shown.

[0019] Figure 5 The enlarged schematic diagram of the first test area of ​​the coupon board provided by the present invention is shown. DETAILED DESCRIPTION

[0020] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0021] CAF test modules usually have HW-HW, HW-IL, and IL-IL designs, where HW-IL is the distance from the drill hole wall to the inner copper layer. Its quality requirements are: in addition to not short-circuiting as conventional products, the product HW-IL distance must be as large as possible, and the ideal state is to be close to the design value to reduce the reduction in insulation distance caused by processing alignment deviation. Any HW-IL offset in any inner layer of the hole chain will result in failure to pass hundreds or even thousands of hours of high temperature and high humidity environment testing, such as temperature 85°C + humidity 85%RH + bias 100V~1500V + duration 500~2500 hours. Thus, defective products are produced. In order to solve the above problems, the present invention provides the following embodiments.

[0022] Embodiment 1: Figure 1 The first embodiment of a CAF grading and screening method of the present invention is shown, and the present invention is applied to CAF testing of PCB products. The specific method includes: 110, adding a process edge to the coupon board, the process edge having a plurality of test areas, each of the test areas having a different HW-IL spacing; in step 110, the test area includes a first test point and a second test point, and when testing the test area, two probes of a multimeter are connected to the first test point and the second test point for testing. In a specific example, the number of test areas may be 3, the 3 test areas are the first test area, the second test area, and the third test area, the HW-IL spacing of the first test area is 50um, the HW-IL spacing of the second test area is 62.5um, and the HW-IL spacing of the third test area is 75um.

[0023] 120, according to the size of the HW-IL spacing, the test area is subjected to a step-by-step continuity test. In step 120, according to the size of the HW-IL spacing, the test area is subjected to a step-by-step continuity test, specifically including: according to the size of the HW-IL spacing, the test areas are sorted in ascending order; firstly, the first test area is subjected to a continuity test, if the test passes, the current product is a Class A product; when the first test area fails the test, the second test area is subjected to a continuity test, if the test passes, the current product is a Class B product; when the second test area fails the test, the third test area is subjected to a continuity test, if the test passes, the current product is a Class C product; when the third test area fails the test, the current product is an unqualified product.

[0024] The present invention adds a process edge to the coupon board, wherein the process edge has multiple test areas, each of which has a different HW-IL spacing; and performs a level-by-level on-off test on the test area according to the size of the HW-IL spacing. This realizes graded alignment and screening of coupons, solves the problem that the alignment of CAF HW-IL cannot be accurately and quantitatively monitored, and meets the strict quality and testing requirements of CAF products.

[0025] Embodiment 2: Based on Example 1, the second embodiment of a CAF grading and screening method provided by the present invention, when designing a coupon board, the present invention makes a coupon pattern according to the CAF HW-IL grading and alignment screening, adds the process edge of the CAF test module to the coupon board, the process edge width can be 9mm, and the HW-IL spacing is designed in 3 different levels: 50um / 62.5um / 75um, which is only used as an example here, and other spacings or more different levels can also be designed. The principle is based on the best processing capacity of the manufacturer and ensuring that the insulation distance is sufficient. There is no requirement for the inner copper width, which is usually greater than 125um, and it can meet the line etching capacity of each manufacturer. The present invention adds a process edge to the coupon board, and the process edge has multiple test areas, each of which has a different HW-IL spacing; according to the size of the HW-IL spacing, the test area is tested step by step. The grading and alignment screening of coupons is realized, which solves the problem that the alignment of CAF HW-IL cannot be accurately quantified and monitored, and meets the strict quality and testing requirements of CAF products.

[0026] In some optional embodiments, see Figure 4 , A is the test point, and B is the second test point. The test area includes a first test point and a second test point. When testing the test area, the two probes of the multimeter are connected to the first test point and the second test point for testing. The first test point connects all inner layers, and the first test point is connected to the outer circular PAD of the coupon board. The diameter of the outer circular PAD is 2mm, and the solder mask window is 0.076mm. The second test point connects all drill holes, and the second test point is connected to the outer square PAD of the coupon board. The size of the outer square PAD is 6.5*4.5mm, and the solder mask window is 6.576*4.576mm.

[0027] In another implementation of the above embodiment, see Figure 5, the first test point may also include an A test point and at least one N test point, wherein the A test point connects all inner layers of the coupon board; the N test point is the L(N) inner layer to the outer layer of the coupon board. The N test point is the inner layer test point that needs to be monitored on the coupon board, and the N test point is set according to the number of inner layers that need to be monitored on the coupon board. In a specific example, the number of the first test points is 9, the A test point connects all inner layers of the coupon board, and the 1~6 test points are respectively connected to the inner layer L2 / L3 / L4 / L5 / L6 / L7 of the outer layer; the N-1 test point is the inner layer L(N-1) connected to the outer layer; the N test point is the inner layer L(N) connected to the outer layer, N is equal to the number of inner layers that need to be monitored, and the number of test points can be increased with N.

[0028] In some optional embodiments, see Figure 3-4 , a is the first test area, b is the second test area, c is the third test area; HW-IL spacing is as follows Figure 3 As shown. The number of test areas is 3, and the 3 test areas are the first test area, the second test area, and the third test area. The HW-IL spacing of the first test area is 50um, the HW-IL spacing of the second test area is 62.5um, and the HW-IL spacing of the third test area is 75um. In this embodiment, the first test area is Coupon 50um, the drill nozzle is 0.3mm, the distance between the HW-IL drill nozzle and the surrounding inner copper layer is the clearance ring width, and the HW-IL spacing is 50um. The second test area is Coupon62.5um, the distance between the drill nozzle 0.3mm, the HW-IL drill nozzle and the surrounding inner copper layer is the clearance ring width, and the HW-IL spacing is 62.5um. The third test area is Coupon75um, the distance between the drill nozzle 0.3mm, the HW-IL drill nozzle and the surrounding inner copper layer is the clearance ring width, and the HW-IL spacing is 75um.

[0029] In some optional embodiments, see Figure 2 , according to the size of the HW-IL spacing, the test area is subjected to a level-by-level continuity test, specifically including: 210, sorting the test areas in ascending order according to the size of the HW-IL spacing; 220, first perform a continuity test on the first test area, if the test passes, the current product is a Class A product; 230, when the first test area fails the test, a continuity test is performed on the second test area. If the test passes, the current product is a Class B product; 240, when the second test area fails the test, a continuity test is performed on the third test area. If the test passes, the current product is a Class C product; 250. When the third test area fails the test, the current product is an unqualified product.

[0030] In step 210-step 250, after designing and processing the PCB, the present application performs quality grading and selection, and uses a multimeter to perform continuity test on the selected coupons, and connects the probe of the multimeter to the first test point and the second test point for testing. The measurement order of different spacings is to start with the small spacing and select the board: In step 220, the small pitch of 50um is not short-circuited (the multimeter does not sound), so the effective insulation distance of the actual test module CAF HW-IL channel is 125um (175um-50um), the quality is OK, and it is a Class A product.

[0031] In step 230, if good products cannot be selected with a spacing of 50um, a medium spacing of 62.5um without short circuit can be selected, that is, the HW-IL insulation distance is greater than 112.5um (175um-62.5um), which is a Class B product.

[0032] In step 240, if good products cannot be selected from the spacings of 50um and 62.5um, a board with a spacing of 75um and no short circuit can be selected, that is, the HW-IL insulation distance is greater than 100um (175um-75um), which is a Class C product.

[0033] In step 250, if good products cannot be selected from the spacings of 50um, 62.5um, and 75um, it means that the HW-IL alignment accuracy is too poor and the current product is unqualified.

[0034] In some optional embodiments, if the current product is a substandard product, the multimeter probe is used to respectively test the N test points and the second test point in any test area to locate the abnormal inner layer of the current product, generate abnormal data, and re-make the board based on the abnormal data. In this embodiment, the coupon is combined to perform quality abnormality analysis, and the multimeter contacts the second test point and the N test points of any inner layer (L2~LN), which can accurately locate which specific inner layer has an abnormality. Then optimize the process to re-make the board, and repeat the above steps to select good products.

[0035] The present invention can achieve the following effects through this CAF grading and screening method: accurate grading, higher precision requirements. Design three-level test points, detect them one by one, and have the effect of grading the board line deviation. The products are divided into A grade>B grade>C grade, so as to flexibly select the product grade in combination with the difficulty of CAF test and customer delivery requirements. Design a common PTH test point to connect all inner layers, and select A / B / C grade products quickly and efficiently. Design a PTH hole in each L2~L(N), respectively connect the inner layer to the outer layer test point, so as to facilitate the positioning of the problem layer layer by layer after short circuit for abnormal analysis.

[0036] Embodiment 3: According to another aspect of an embodiment of the present invention, a CAF grading and screening device is provided, and the device is used to execute the above-mentioned CAF grading and screening manufacturing method, and is used to perform continuity tests on products. The present invention adds a process edge to the coupon board, and the process edge has multiple test areas, each of which has a different HW-IL spacing; according to the size of the HW-IL spacing, the test areas are subjected to step-by-step continuity tests. The implementation of graded alignment screening of coupons solves the problem that the alignment of CAFHW-IL cannot be accurately quantified and monitored, and meets the stringent quality and testing requirements of CAF products.

[0037] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. Similarly, in order to simplify the present invention and help understand one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Wherein, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, wherein each claim itself is a separate embodiment of the present invention.

[0038] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive.

[0039] It should be noted that the above embodiments illustrate the present invention rather than limit it, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present invention may be implemented with the aid of hardware comprising several different elements and with the aid of appropriately programmed computers. In a unit claim that lists several systems, several of these systems may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be understood as limitations on the order of execution.

Claims

1. A CAF grading and screening method, characterized in that: The method comprises: Adding a process edge on the coupon board, wherein the process edge has a plurality of test areas, each of the test areas having a different HW-IL spacing; According to the size of the HW-IL spacing, the test area is subjected to a step-by-step on-off test.

2. A CAF grading screening method according to claim 1, characterized in that: The test area includes a first test point and a second test point. When testing the test area, two probes of a multimeter are connected to the first test point and the second test point respectively for testing.

3. A CAF grading screening method according to claim 2, characterized in that: The first test point is connected to all inner layers, and the first test point is connected to the outer circle PAD of the coupon board, the outer circle PAD has a diameter of 2 mm, and the solder mask opening is 0.076 mm.

4. A CAF grading screening method according to claim 2, characterized in that: The first test points include an A test point and at least one N test point, wherein the A test point connects all inner layers of the coupon board; and the N test point is from the L(N) inner layer to the outer layer of the coupon board.

5. A CAF grading screening method according to claim 4, characterized in that: The N test points are inner layer test points of the coupon board that need to be monitored, and the N test points are set according to the number of inner layers of the coupon board that need to be monitored.

6. A CAF grading screening method according to claim 2, characterized in that: The second test point is connected to all the drill holes, and the second test point is connected to the outer square PAD of the coupon board. The outer square PAD has a size of 6.5*4.5 mm, and the solder mask window has a size of 6.576*4.576 mm.

7. A CAF grading screening method according to claim 1, characterized in that: The number of the test areas is 3, which are the first test area, the second test area, and the third test area. The HW-IL spacing of the first test area is 50um, the HW-IL spacing of the second test area is 62.5um, and the HW-IL spacing of the third test area is 75um.

8. A CAF grading and screening method according to claim 7, characterized in that: The step-by-step on-off test of the test area according to the size of the HW-IL spacing specifically includes: According to the size of the HW-IL spacing, the test areas are sorted from small to large; First, the first test area is tested for continuity. If the test passes, the current product is a Class A product. If the first test area fails the test, the second test area is tested for continuity. If the test passes, the current product is a Class B product. When the second test area fails the test, the third test area is tested for continuity. If the test passes, the current product is a Class C product. When the third test area fails the test, the current product is a substandard product.

9. A CAF grading screening method according to claim 8, characterized in that: If the current product is a substandard product, the abnormal inner layer of the current product is located by respectively testing the N test points and the second test point in any test area through a multimeter probe, generating abnormal data; and re-making the board according to the abnormal data.

10. A CAF grading and screening device, characterized in that: The device is used to execute the CAF grading screening production method according to any one of claims 1 to 9, and is used to perform continuity testing on products.

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