Printed circuit board and back drilling reliability test module thereof

Abstract

The utility model discloses a printed circuit board and a back drill reliability test module thereof. The test module is attached to a board edge of a working board of the printed circuit board. The test module comprises at least one test sub-module; the test sub-module comprises a plurality of test back drilling holes and a plurality of hole chain test holes; the test sub-module comprises a back-drilling knife-in surface layer, a plurality of back-drilling through layers and at least one back-drilling winding layer; the back drilling winding layer is arranged on at least part of the back drilling through layer; the back drilling knife-in surface layer comprises a plurality of hole chain test bonding pads; the hole chain test bonding pads are connected with the hole chain test holes in a one-to-one correspondence manner; each back drilling winding layer comprises a plurality of conductive hole rings which are distributed around each test back drilling hole in one-to-one correspondence with each test back drilling hole; the adjacent conductive hole rings are connected with each other; and the at least two conductive hole rings are respectively connected with one hole chain test hole. According to the technical scheme of the utility model, the reliability of the back drill in the printed circuit board can be detected on line, and the detection speed and the reliability of the result can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of printed circuit board testing, in particular to a printed circuit board and a back-drilling reliability testing module thereof. Background Art

[0002] In the design of high-speed printed circuit boards (PCBs), the back-drilling process is essential to avoid damaging impedance continuity and signal integrity. As a "surgical" process for a local part of the PCB, back-drilling is somewhat destructive to the PCB itself. The use of the back-drilling process makes the PCB prone to the phenomenon of conductive anodic filamentation (CAF).

[0003] CAF refers to the leakage phenomenon of copper and copper salts during the migration of copper ions inside the PCB from the anode (high voltage) along the micro-column channels between glass fiber filaments to the cathode (low voltage). CAF phenomena may occur between holes in the PCB, between holes and inner / outer layer conductors, and between outer layer conductors. When the PCB is powered on and working in a high-temperature and high-humidity environment, CAF phenomena may occur between two insulated conductors, such as between holes, between holes and inner / outer layer conductors, or between outer layer conductors, etc., which will ultimately lead to problems such as poor insulation and short-circuit failure of the PCB.

[0004] However, there are relatively few current studies on the CAF performance related to exploring the reliability of back-drilled boards. There is an existing technology that designs a winding beside the back-drilled hole. Theoretically, the winding is insulated from the via hole corresponding to its corresponding back-drilled hole. Therefore, it tests the reliability of the back-drilling by measuring the resistance value between the via hole and the winding. However, this technology can only determine whether there are failure problems in the PCB, but cannot quickly locate the position of the failure, cannot accurately quantify the failure phenomenon, and its practicality in the analysis of PCB processing technology capabilities is poor. Summary of the Utility Model

[0005] The utility model provides a printed circuit board and a back-drilling reliability testing module thereof to solve the problems existing in the prior art, realize the online detection of the reliability of back-drilling in the printed circuit board, and quickly analyze the position where the failure occurs, which is beneficial to improving the detection speed and the reliability of the results.

[0006] In a first aspect, the utility model provides a back-drilling reliability testing module for a printed circuit board. The testing module is attached to the edge of the working board of the printed circuit board. The testing module includes:

[0007] At least one testing sub-module;

[0008] Each of the test sub - modules includes a plurality of test back - drilled holes and a plurality of via - chain test holes;

[0009] The test sub - module includes a back - drill entry layer, a plurality of back - drill through - layers, and at least one back - drill winding layer;

[0010] The back - drill winding layer is disposed on at least a part of the back - drill through - layers;

[0011] The back - drill entry layer includes a plurality of via - chain test pads; each of the via - chain test pads is respectively and correspondingly connected to each of the via - chain test holes;

[0012] Each of the back - drill winding layers includes a plurality of conductive via - rings distributed around each of the test back - drilled holes and corresponding to each of the test back - drilled holes; adjacent conductive via - rings are connected to each other; at least two of the conductive via - rings are respectively connected to a via - chain test hole.

[0013] Optionally, each of the test back - drilled holes is evenly distributed in a rectangular array;

[0014] The connection of adjacent conductive via - rings to each other includes: each of the conductive via - rings adjacent in the first direction is connected to each other, and each of the conductive via - rings adjacent in the second direction is connected to each other; the first direction is perpendicular to the second direction.

[0015] Optionally, the via - chain test hole includes a first test hole and a second test hole;

[0016] The conductive via - rings located at the diagonal positions of the rectangular array are respectively a first conductive via - ring and a second conductive via - ring;

[0017] The first conductive via - ring is connected to the first test hole; the second conductive via - ring is connected to the second test hole.

[0018] Optionally, the inner - ring diameter A of the conductive via - ring = D + 2d1; where D is the diameter of the test back - drilled hole, and d1 is the distance from the conductive via - ring to the corresponding test back - drilled hole.

[0019] Optionally, it further includes: at least one back - drill anti - pad layer;

[0020] Each of the back - drill anti - pad layers is correspondingly arranged with each of the back - drill winding layers, and each of the back - drill anti - pad layers and the corresponding back - drill winding layer are located on opposite sides of the same core board;

[0021] Each of the back - drill anti - pad layers includes a plurality of anti - pads distributed around each of the test back - drilled holes and corresponding to each of the test back - drilled holes.

[0022] Optionally, the inner ring diameter A of the anti-pad is A = D + 2d2; where D is the diameter of the test back drill hole, and d2 is the distance from the anti-pad to the corresponding test back drill hole.

[0023] Optionally, the distance from the conductive hole ring to the corresponding test back drill hole is equal to the distance from the anti-pad to the corresponding test back drill hole.

[0024] Optionally, the back drill entry layer further includes back drill depth information and an indication of the distance from the anti-pad to the corresponding test back drill hole.

[0025] Optionally, the distance from the conductive hole ring to the corresponding test back drill hole may include at least one of 76.2um, 101.6um, 114.3um, and 127um.

[0026] In a second aspect, the present invention further provides a printed circuit board, comprising: the back drill reliability test module of the printed circuit board according to any one of the above; the test module is attached to the edge of the working board of the printed circuit board.

[0027] The technical solution of the present invention enables the test module to be attached to the edge of the working board of the printed circuit board. The test module includes at least one test sub-module, and each test sub-module includes a plurality of test back drill holes and via chain test holes; the test sub-module includes a back drill entry layer, a plurality of back drill through layers, and at least one back drill winding layer, and the back drill winding layer is disposed on at least part of the back drill through layers; the back drill entry layer includes a plurality of via chain test pads, and each via chain test pad is respectively connected to each via chain test hole in one-to-one correspondence. Each back drill winding layer includes a plurality of conductive hole rings distributed around each test back drill hole corresponding to each test back drill hole, and adjacent conductive hole rings are connected to each other. At least two conductive hole rings are respectively connected to a via chain test hole. After the conductive hole rings of each back drill winding layer are connected to each other, they are connected to the via chain test pads through two via chain test holes, so that by measuring the resistance between the via chain test pads, the on-line detection of the reliability of the back drill in the printed circuit board can be realized. At the same time, by setting a plurality of back drill winding layers, the position where the failure occurs can be quickly analyzed, which is beneficial to improving the detection speed and the reliability of the results.

[0028] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 Schematic diagram of the back-drilling entry layer of the test module provided by the embodiment of the present invention;

[0031] Figure 2 Schematic diagram of the back-drilling through layer of the test module provided by the embodiment of the present invention;

[0032] Figure 3 Schematic diagram of the back-drilling winding layer of the test module provided by the embodiment of the present invention;

[0033] Figure 4 Schematic diagram of the back-drilling anti-pad layer of the test link provided by the embodiment of the present invention;

[0034] Figure 5 Schematic diagram of a printed circuit board provided by the embodiment of the present invention. Detailed implementation manners

[0035] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0037] This embodiment provides a back-drilling reliability test module for a printed circuit board. Figure 1 Schematic diagram of the back-drilling entry layer of the test module provided by the embodiment of the present invention. Figure 2 Schematic diagram of the back-drilling through layer of the test module provided by the embodiment of the present invention. Figure 3The figure is a schematic structural diagram of the back-drilled wiring layer of the test module provided by the embodiment of the present invention. With reference to Figures 1-3 As shown, the back-drilling reliability test module 100 of the printed circuit board includes at least one test sub-module 10. Each test sub-module 10 includes a plurality of test back-drilled holes 11 and a plurality of via chain test holes 12; the test sub-module 10 includes a back-drilling entry surface layer, a plurality of back-drilling through layers, and at least one back-drilled wiring layer; the back-drilled wiring layer is disposed on at least part of the back-drilling through layers; the back-drilling entry surface layer includes a plurality of via chain test pads 13; each via chain test pad 13 is respectively connected to each via chain test hole 12 in a one-to-one correspondence; each back-drilled wiring layer includes a plurality of conductive hole rings 14 distributed around each test back-drilled hole 11 corresponding to each test back-drilled hole 11; adjacent conductive hole rings 14 are connected to each other; at least two conductive hole rings 14 are respectively connected to a via chain test hole 12.

[0038] Among them, the printed circuit board is a multi-layer printed circuit board. The printed circuit board includes a working board and a test board located at the edge of the working board. The working board includes at least one working back-drilled hole. The test module is located on the test board of the printed circuit board, so that the test module can be prepared in the same process as the working board. By performing electrical performance tests on the test module, the reliability of the working back-drilled holes in the working board can be verified.

[0039] The test module 100 includes at least one test sub-module 10. It can be understood that the test module 100 includes one test sub-module 10, or the test module 100 includes a plurality of test sub-modules 10. When the test module 100 includes a plurality of test sub-modules 10, the number of back-drilling through layers and back-drilled wiring layers in each test sub-module 10, and the back-drilling through layers where each back-drilled wiring layer is located can be the same or different.

[0040] The test back-drilled holes 11 are formed in the same process as the working back-drilled holes, so that the performance of the test back-drilled holes 11 can be the same as that of the working back-drilled holes. Thus, the resistance value of the test back-drilled holes 11 can be converted into the electrical performance of the working back-drilled holes. Therefore, by detecting the resistance value of the test back-drilled holes 11, the reliability of the working back-drilled holes in the working board can be known.

[0041] The via chain test holes 12 are conductive vias. By connecting the conductive hole rings 14 in the back-drilled wiring layer to the via chain test holes 12, when an external device is connected to the via chain test holes 12, the resistance value of the conductive hole rings 14 can be tested.

[0042] It should be noted that Figure 1Only an example is shown where the test module includes 9 test sub-modules 10, and each test sub-module 10 includes 24 test back-drilled holes 11. This is not a limitation on the number of test sub-modules 10 in the test module and the number of test back-drilled holes 11 in each test sub-module 10. In other embodiments, the test area may also include 12 test sub-modules 10, and in each test sub-module 10, the number of test back-drilled holes 11 is different. The number of test sub-modules 10 in the test module and the number of test back-drilled holes 11 in each test sub-module 10 can be determined according to the requirement for the accuracy of the test results; the more the number of test sub-modules 10, and the more the number of test back-drilled holes 11 in each test sub-module 10, the higher the accuracy of the test results.

[0043] The back-drilling into the tooling layer is the last layer of the printed circuit board. The back-drilling into the tooling layer includes a plurality of via chain test pads 13, and each via chain test pad 13 is respectively connected to each via chain test hole 12 in a one-to-one correspondence, so that an external device can be connected to the corresponding via chain test hole 12 through the via chain test pad 13, and further the resistance value of the conductive via ring 14 can be tested.

[0044] Optionally, the back-drilling into the tooling layer further includes an indication of the back-drilling depth information and the distance from the anti-pad to the corresponding test back-drilled hole 11.

[0045] Among them, the back-drilling depth information may include, but is not limited to, that the back-drilling must penetrate layer MCL and the back-drilling must not penetrate layer MNC. Refer to Figure 1 As shown, an indication of the back-drilling depth information and the distance from the anti-pad to the corresponding test back-drilled hole 11 (unit: μm) is set at the edge of the test module, so that the test results can be quickly analyzed, which is beneficial to improving the test efficiency.

[0046] Back-drilling means that after the hole is metallized, a drill bit larger than the drilled hole is used to remove the conductive via stub by drilling, so as to achieve the purpose of optimizing impedance continuity and signal integrity and reducing signal distortion. For example, in a 12-layer multi-layer board, there is a through-hole from layer 1 to layer 12, but this through-hole is only applicable to the signal from layer 1 to layer 3. Therefore, there will be a stub after layer 3 for this through-hole. This structure causes resonance and reflection at high frequencies, thus reducing the signal at the resonant frequency. Therefore, the back-drilling process can be performed after layer 4 to layer 12 to remove the copper plating in the through-holes from layer 4 to layer 12, so as to avoid signal distortion. The back-drilling penetration layer refers to the layer where the copper plating in the through-hole is removed by the back-drilling process, such as layer 4 to layer 12 in the above embodiment. The printed circuit board also includes a back-drilling non-penetration layer, that is, the layer where the copper plating in the through-hole cannot be removed by the back-drilling process, such as layer 1 to layer 3 in the above embodiment.

[0047] It should be noted that the number of layers that can be drilled through by back drilling can be determined according to the depth of each working back drilling hole in the working board. In an exemplary embodiment, taking a 16-layer board as an example, the working board includes working back drilling holes with depths from the 16th layer to the 4th layer, from the 16th layer to the 6th layer, and from the 16th layer to the 11th layer. Then, the back drilling through layers in the test sub-module 10 can be from the 16th layer to the 4th layer, from the 16th layer to the 6th layer, and from the 16th layer to the 11th layer, or, from the 16th layer to the 6th layer and from the 16th layer to the 11th layer, or, from the 16th layer to the 6th layer and from the 16th layer to the 11th layer, etc.

[0048] The back drilling winding layer is disposed on at least part of the back drilling through layer. It can be understood that there is one or more back drilling through layers on which the back drilling winding layer is disposed. Since the back drilling winding layer includes a plurality of conductive hole rings 14 distributed around each test back drilling hole 11 corresponding to each test back drilling hole 11 one by one, the more the number of back drilling winding layers, the finer the test of the CAF phenomenon, and thus the higher the accuracy of the CAF test result. By connecting adjacent conductive hole rings 14 to each other, at least two conductive hole rings 14 are respectively connected to a via chain test hole 12. Thus, by connecting an external device to the via chain test hole 12, the back drilling reliability of the printed circuit board can be tested.

[0049] In this embodiment, by attaching the test module to the edge of the working board of the printed circuit board, the test module includes at least one test sub-module, and each test sub-module includes a plurality of test back drilling holes and each via chain test hole; the test sub-module includes a back drilling entry surface layer, a plurality of back drilling through layers, and at least one back drilling winding layer, and the back drilling winding layer is disposed on at least part of the back drilling through layers; the back drilling entry surface layer includes a plurality of via chain test pads, and each via chain test pad is respectively connected to each via chain test hole one by one. Each back drilling winding layer includes a plurality of conductive hole rings 14 distributed around each test back drilling hole corresponding to each test back drilling hole one by one. Adjacent conductive hole rings are connected to each other, and at least two conductive hole rings are respectively connected to one of the via chain test holes. Thus, after the conductive hole rings of each back drilling winding layer are connected to each other, they are connected to the via chain test pads through two via chain test holes, so that by measuring the resistance between the via chain test pads, the on-line detection of the back drilling reliability in the printed circuit board can be realized. At the same time, by setting a plurality of back drilling winding layers, the position where the failure occurs can be quickly analyzed, which is beneficial to improving the detection speed and the reliability of the result.

[0050] Optionally, continuing to refer to Figure 1 As shown, the test back drilling holes 11 are evenly distributed in a rectangular array; the connection of adjacent conductive hole rings 14 to each other includes: connecting the conductive hole rings 14 adjacent to each other along the first direction L1 and connecting the conductive hole rings 14 adjacent to each other along the second direction L2, so that the structure of the test module is compact, which is beneficial to the miniaturization of the test module.

[0051] Wherein, the first direction L1 is perpendicular to the second direction L2.

[0052] It should be noted that Figure 1 Only an example is shown where the test module includes 12 test sub-modules 10, and each test sub-module 10 includes test back-drilled holes 11 evenly distributed in a 4×6 rectangular array. This does not limit the number of test sub-modules 10, the number of test back-drilled holes 11 in each test sub-module 10, and the arrangement method. It can be understood that to improve the reliability of the test results, as many test sub-modules 10 as possible can be set in the limited space at the edge of the printed circuit board, and as many test back-drilled holes 11 as possible can be set in each test module.

[0053] Optionally, the via chain test via 12 includes a first test via 121 and a second test via 122; the conductive via rings 14 located at the diagonal positions of the rectangular array are respectively a first conductive via ring 141 and a second conductive via ring 142; the first conductive via ring 141 is connected to the first test via 121; the second conductive via ring 142 is connected to the second test via 122.

[0054] Wherein, the first conductive via ring 141 and the second conductive via ring 142 can be two conductive via rings 14 located at any diagonal position in the conductive via rings 14 of the rectangular array. For example, the upper left conductive via ring 14 and the lower right conductive via ring 14, or the lower left conductive via ring 14 and the upper right conductive via ring 14, etc. By connecting the first conductive via ring 141 to the first test via 121 and the second conductive via ring 142 to the second test via 122, when an external device is connected to the conductive via rings 14 through the first test via 121 and the second test via 122, the electrical performance of each conductive via ring 14 can be measured.

[0055] It should be noted that Figure 3 Only an example is shown where the upper left conductive via ring 14 is the first conductive via ring 141, the lower right conductive via ring 14 is the second conductive via ring 142, the first conductive via ring 141 is connected to the first test via 121, and the second conductive via ring 142 is connected to the second test via 122. This does not limit the connection situation between the conductive via rings 14 and the via chain test via 12. As long as two conductive via rings 14 located at any diagonal position in the conductive via rings 14 of the rectangular array are respectively connected to the two via chain test vias 12, it is acceptable.

[0056] Optionally, Figure 4 This is a schematic structural diagram of the back-drilled anti-pad layer of the test link provided by the embodiment of the present invention. Refer to Figure 4As shown, the backdrill reliability test module of the printed circuit board further includes: at least one backdrill anti-pad layer; each backdrill anti-pad layer is arranged in one-to-one correspondence with each backdrill winding layer, and each backdrill anti-pad layer and the corresponding backdrill winding layer are located on opposite sides of the same core board; each backdrill anti-pad layer includes a plurality of anti-pads 15 distributed around each test backdrill hole 11 and corresponding to each test backdrill hole 11 one by one.

[0057] Among them, the backdrill anti-pad layer and the corresponding backdrill winding layer are located on opposite sides of the same core board, so that the backdrill winding layer and the backdrill anti-pad layer are isolated and insulated from each other.

[0058] Optionally, the distance from the conductive via ring 14 to the corresponding test backdrill hole 11 is equal to the distance from the anti-pad 15 to the corresponding test backdrill hole 11, so as to ensure the accuracy of the backdrill reliability test of the printed circuit board.

[0059] Optionally, the inner ring diameter A of the conductive via ring 14 = D + 2d1; the inner ring diameter A of the anti-pad 15 = D + 2d2, so as to effectively test the CAF phenomenon of the printed circuit board and ensure the reliability of the test results.

[0060] Among them, D is the diameter of the test backdrill hole 11, d1 is the distance from the conductive via ring 14 to the corresponding test backdrill hole 11, and d2 is the distance from the anti-pad 15 to the corresponding test backdrill hole 11.

[0061] In an alternative embodiment, the distance from the test backdrill hole 11 to the anti-pad 15 in the test module is equal to the distance from the working backdrill hole in the working board to the anti-pad 15, so that the structures of the test backdrill hole 11 and the working backdrill hole are the same, which is beneficial to further improving the accuracy of online detection of the reliability of backdrilling in the printed circuit board.

[0062] Optionally, the distance from the conductive via ring 14 to the corresponding test backdrill hole 11 may include at least one of 76.2um, 101.6um, 114.3um, and 127um. The distance from the anti-pad 15 to the corresponding test backdrill hole 11 may include at least one of 76.2um, 101.6um, 114.3um, and 127um.

[0063] Based on the same concept, this embodiment also provides a printed circuit board. Figure 5 It is a schematic structural diagram of a printed circuit board provided by an embodiment of the present invention. Refer to Figure 5As shown in the figure, the printed circuit board includes the backdrill reliability test module 100 of the printed circuit board provided in any of the above embodiments. The test module 100 is attached to the edge of the working board 01 of the printed circuit board. Therefore, the printed circuit board provided in this embodiment has the corresponding structure and features of the preparation method of the gold finger of the PCB provided in any of the above embodiments, and can achieve the beneficial effects of the backdrill reliability test module of the printed circuit board provided in any of the above embodiments. The same parts can be referred to the above description.

[0064] Embodiment 1

[0065] Continue to refer to Figure 1 As shown in the figure, taking a 16-layer printed circuit board as an example in this embodiment, according to the test requirements, the test module provided in this embodiment includes 3 types of backdrill drill-through layers and 12 test sub-modules 10 for testing the distances from 4 test backdrill holes 11 to anti-pads 15. Each test sub-module 10 is a CAF test unit. It should be noted that the backdrill reliability test module of the printed circuit board can be flexibly adjusted according to the change of test requirements.

[0066] "MNC L3 MCL5" means "L5 layer must be drilled through, L3 layer cannot be drilled through". Therefore, from L16 layer to L5 layer are all backdrill drill-through layers. According to the test requirements, at least one layer among L16 layer to L5 layer is set as a backdrill winding layer. The backdrill winding layer includes a plurality of conductive hole rings 14 distributed around each test backdrill hole 11 corresponding to each test backdrill hole 11. That is, 1 to 12 layers of conductive hole rings 14 can be set from L16 layer to L5 layer. The distances from the test backdrill hole 11 to the conductive hole ring 14 (the same as the distance from the test backdrill hole 11 to the anti-pad 15) are 76.2um, 101.6um, 114.3um, and 127um respectively.

[0067] "MNC L5 MCL7" means "L7 layer must be drilled through, L5 layer cannot be drilled through". Therefore, from L16 layer to L7 layer are all backdrill drill-through layers. According to the test requirements, at least one layer among L16 layer to L7 layer is set as a backdrill winding layer. The backdrill winding layer includes a plurality of conductive hole rings 14 distributed around each test backdrill hole 11 corresponding to each test backdrill hole 11. That is, 1 to 10 layers of conductive hole rings 14 can be set from L16 layer to L7 layer. The distances from the test backdrill hole 11 to the conductive hole ring 14 (the same as the distance from the test backdrill hole 11 to the anti-pad 15) are 76.2um, 101.6um, 114.3um, and 127um respectively.

[0068] "MNC L10 MCL12" means "it is necessary to drill through layer L12 and not drill through layer L10". Therefore, from layer L16 to layer L12 are all back-drilled through layers. According to the test requirements, at least one layer from layer L16 to layer L12 is set as a back-drilled winding layer. The back-drilled winding layer includes a plurality of conductive hole rings 14 distributed around each test back-drilled hole 11 corresponding to each test back-drilled hole 11 one by one. That is, 1 to 5 layers of conductive hole rings 14 can be set from layer L16 to layer L12. The distances from the test back-drilled hole 11 to the conductive hole ring 14 (the same as the distance from the test back-drilled hole 11 to the anti-pad 15) are 76.2um, 101.6um, 114.3um, and 127um respectively.

[0069] For example, conductive hole rings 14 can be designed on 3 layers, namely L12, L10, and L8, of the "MNC L3 MCL5" unit, on 2 layers, namely L10 and L8, of the "MNC L5 MCL7" unit, and on layer L12 of the "MNC L10 MCL12" unit.

[0070] According to the above design, 3 types of back-drilled CAF channels that can present the distances from each test back-drilled hole 11 to the conductive hole ring 14 can be presented in each test sub-module 10. In this way, during the CAF test, if there is a CAF NG (i.e., CAF failure) phenomenon, then through the test results of each test sub-module 10, it can be quickly analyzed which layer of the printed circuit board the CAF NG appears on.

[0071] For example, if you want to evaluate the back-drilling reliability with a test voltage of 100V for 300 hours in a temperature and humidity environment (temperature 80°C / humidity 85%) and the distances from the back-drilled hole to the wire (the same as the distance from the back-drilled hole to the anti-pad 15) are 76.2um, 101.6um, 114.3um, and 127um respectively, 500 test modules of the same batch can be selected for the CAF test.

[0072] After the test is completed, compare the CAF test data with the reliability CAF comparison table of a certain type of product. If it reaches the corresponding standard value in the table, it is the back-drilling reliability process capability for manufacturing this type of product.

[0073] The above specific implementation manners do not constitute a limitation to the protection scope of the present utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A backdrilling reliability test module for a printed circuit board, characterized in that, The test module is attached to the edge of the working board of the printed circuit board; The test module includes: At least one test sub-module; Each of the test sub-modules includes a plurality of test back-drilled holes and a plurality of via chain test holes; The test sub-module includes a back-drilling entry layer, a plurality of back-drilling through layers, and at least one back-drilling winding layer; The back-drilling winding layer is disposed on at least a part of the back-drilling through layers; The back-drilling entry layer includes a plurality of via chain test pads; each of the via chain test pads is respectively connected to each of the via chain test holes in a one-to-one correspondence; Each of the back-drilling winding layers includes a plurality of conductive via rings distributed around each of the test back-drilled holes and corresponding to each of the test back-drilled holes; adjacent conductive via rings are connected to each other; at least two of the conductive via rings are respectively connected to a via chain test hole.

2. The backdrilling reliability test module of the printed circuit board according to claim 1, wherein, Each of the test back-drilled holes is uniformly distributed in a rectangular array; The connection of adjacent conductive via rings to each other includes: the conductive via rings adjacent to each other in the first direction are connected to each other, and the conductive via rings adjacent to each other in the second direction are connected to each other; The first direction is perpendicular to the second direction.

3. The back drilling reliability test module of the printed circuit board according to claim 2, wherein, The via chain test hole includes a first test hole and a second test hole; The conductive via rings located at the diagonal positions of the rectangular array are respectively a first conductive via ring and a second conductive via ring; The first conductive via ring is connected to the first test hole; the second conductive via ring is connected to the second test hole.

4. The backdrilling reliability test module of the printed circuit board according to claim 2, wherein The inner diameter A of the conductive via ring = D + 2d1; wherein, D is the diameter of the test back-drilled hole, and d1 is the distance from the conductive via ring to the corresponding test back-drilled hole.

5. The backdrilling reliability test module of the printed circuit board according to claim 4, characterized in that, It further includes: At least one back-drilling anti-pad layer; Each of the back-drilling anti-pad layers is provided corresponding to each of the back-drilling winding layers, and each of the back-drilling anti-pad layers and the corresponding back-drilling winding layer are located on opposite sides of the same core board; Each of the back-drilling anti-pad layers includes a plurality of anti-pads distributed around each of the test back-drilled holes and corresponding to each of the test back-drilled holes.

6. The backdrilling reliability test module of the printed circuit board according to claim 5, characterized in that, The inner diameter A of the anti-pad = D + 2d2; wherein, D is the diameter of the test back-drilled hole, and d2 is the distance from the anti-pad to the corresponding test back-drilled hole.

7. The backdrilling reliability test module for a printed circuit board according to claim 5 or 6, characterized in that The distance from the conductive via ring to the corresponding test back-drilled hole is equal to the distance from the anti-pad to the corresponding test back-drilled hole.

8. The back drilling reliability test module of the printed circuit board according to claim 5, wherein, The back-drilling entry layer further includes the back-drilling depth information and the identification of the distance from the anti-pad to the corresponding test back-drilled hole.

9. The backdrilling reliability test module of the printed circuit board according to claim 1, characterized in that, The distance from the conductive via ring to the corresponding test back-drilled hole may include at least one of 76.2um, 101.6um, 114.3um, and 127um.

10. A printed circuit board, characterized in that, It includes: The back-drilling reliability test module of the printed circuit board according to any one of claims 1-9; The test module is attached to the edge of the working board of the printed circuit board.

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