Blind hole drawing detection module of HDI circuit board

Abstract

The utility model belongs to the field of PCBs, and discloses a blind hole drawing detection module of an HDI circuit board, which is arranged in a non-product area of the HDI circuit board with four or more circuit layers, and comprises a detection unit used for detecting the binding force of blind holes, the detection unit comprises detection blind holes for conducting different circuit layers, hole copper is filled in the detection blind holes, and the hole copper is filled in the detection blind holes. The hole copper extends to the outside of the hole opening of the detection blind hole to form surface copper, the hole bottom surface of the detection blind hole is inner copper, the hole copper is combined with the inner copper, the surface copper is a part of the outer circuit layer in different circuit layers conducted by the detection blind hole, and the inner copper is a part of the inner circuit layer in the circuit layers conducted by the detection blind hole. And the surface copper of each detection unit is exposed. According to the utility model, the drawing test can be carried out on the detection blind holes of any layer of the finished circuit board, so that the binding force of the blind holes of each layer can be tested and verified, the tested detection blind holes are only subjected to the drawing force in the vertical direction and are not interfered by the transverse force, and the test is more accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of PCB, in particular to an inner layer blind hole pulling detection module of an HDI circuit board. Background Art

[0002] The manufacturing of HDI circuit boards involves a series of complex processes, such as laser drilling to form blind holes and fine electroplating to achieve the construction of the conductive layer in the hole. Any slight deviation in the process parameter control of each step may affect the quality of the blind hole, such as rough hole walls during drilling, uneven plating thickness during electroplating, or loose bonding. Testing the bonding strength between the copper filling in the blind hole and the inner layer circuit can effectively evaluate the quality of the blind holes finally formed by these processes, thereby feedback the problems in the process and facilitate improvement and optimization of production.

[0003] Chinese utility model patent ZL201721339805.4 discloses a HDI circuit board blind hole copper filling reliability test module, the HDI circuit board of the module includes a substrate with an inner copper layer, a dielectric layer covering the inner copper layer is arranged on the substrate, and the dielectric layer in the test area is provided with a number of blind hole units, each blind hole unit contains a plurality of test blind holes arranged in a matrix, the test blind hole is electroplated with a copper filling layer, and the bottom of the copper filling layer is connected to the inner copper layer; the test area is also provided with a surface copper layer covering the blind hole unit. During the test, the solderability of the surface copper and the hole copper is utilized, and the surface copper layer is pulled by external force to pull out the copper in the hole together with the surface copper, so as to quickly verify the reliability of the blind hole electroplating copper filling and detect the copper filling effect in the hole.

[0004] However, the design of the above patent can only detect the surface blind holes of multi-layer HDI circuit boards, but cannot detect the inner blind holes of multi-layer HDI circuit boards. In addition, its inspection method is hand tearing. When tearing horizontally, the horizontal force will affect the detection of the blind hole bonding force. In other words, the unqualified blind holes detected by this module are not necessarily truly unqualified. It may be that the blind holes are not pulled up due to excessive lateral force. The most accurate blind hole inspection method should be to subject the blind holes only to vertical forces. Utility Model Content

[0005] The technical problem to be solved by the utility model is to propose a blind hole pull-out detection module for an HDI circuit board which can perform pull-out detection on both inner and outer blind holes in view of the above technical status.

[0006] The utility model adopts the following technical solution to solve the above technical problems: a blind hole pull-out detection module for an HDI circuit board, characterized in that it is arranged in a non-product area of ​​an HDI circuit board with four or more circuit layers, and comprises a detection unit for detecting the bonding force of the blind hole, the detection unit comprises a detection blind hole that connects the inner and outer circuit layers, the detection blind hole is filled with hole copper, the hole copper extends to the outside of the hole mouth of the detection blind hole to form surface copper, the bottom surface of the detection blind hole is inner copper, the hole copper is combined with the inner copper, the surface copper is a part of the outer circuit layer connected by the detection blind hole, the inner copper is a part of the inner circuit layer connected by the detection blind hole, and the surface copper of each detection unit is exposed.

[0007] Specifically, on the HDI circuit board, a window is opened on the outer side of the detection unit, so that the surface copper of the detection unit is exposed.

[0008] In order to avoid interference between the detection units, preferably, the detection units are staggered on the HDI circuit board.

[0009] In order to make the detection more comprehensive, the utility model improves the position layout of the detection unit. Specifically, the HDI circuit board has n Layer line layer, when n When it is singular, n The circuit layers are recorded from the inside to the outside as level 1 circuit layer, level 2 circuit layer, to ( n +1) / 2 level circuit layer; when n When it is plural, n The circuit layers are recorded from the inside to the outside as the 1st circuit layer to the n / 2 level circuit layer; the detection unit is arranged between circuit layers of different levels.

[0010] Furthermore, each different level of circuit layer is provided with at least one detection unit.

[0011] Specifically, the HDI circuit board has six layers of circuits, including 2 layers of level 1 circuit layer, 2 layers of level 2 circuit layer and 3 layers of level 3 circuit layer from the inside to the outside, and at least one detection unit is set between the level 1 circuit layer and the level 2 circuit layer and between the level 2 circuit layer and the level 3 circuit layer.

[0012] Specifically, the HDI circuit board has eight layers of circuits, including 2 layers each of the 1st level circuit layer, the 2nd level circuit layer, the 3rd level circuit layer and the 4th level circuit layer from the inside to the outside, and at least one detection unit is arranged between the 1st level circuit layer and the 2nd level circuit layer, between the 2nd level circuit layer and the 3rd level circuit layer, and between the 3rd level circuit layer and the 4th level circuit layer.

[0013] Compared with the prior art, the utility model has the advantage that the copper surface of each detection unit of the detection module of the utility model is exposed, so the pull-out test can be performed on the detection blind holes of any layer of the finished circuit board to ensure that the bonding force of the blind holes of each layer can be tested and verified, and the test is comprehensive. In addition, the detection module of the utility model also has an advantage in the force direction during the test. These tested detection blind holes are only subjected to the pull-out force in the vertical direction, without the interference of lateral force, and the test results are more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure and pull-out test of a blind hole detection module of a 6-layer HDI circuit board in the prior art;

[0015] Figure 2 This is a schematic diagram of the blind hole pulling detection module structure and pulling test of Example 1 of the utility model;

[0016] Figure 3~4 Schematic diagram of the preparation method of Example 1 of the present utility model, wherein (a) is drilling, (b) is electroplating, (c) is drilling, (d) is lamination, (e) is exposure, (f) is development, (g) is electroplating, (h) is film removal, and (i) is window opening;

[0017] Figure 5 It is a schematic diagram of the structure and pull-out test of a blind hole detection module for an 8-layer HDI circuit board in the prior art;

[0018] Figure 6 This is a schematic diagram of a blind hole pulling detection module structure and a pulling test according to Embodiment 2 of the present utility model;

[0019] Figures 7-9 Schematic diagram of the process of the preparation method of Example 2 of the utility model, wherein (a) is laminating the insulating layer, (b) is drilling, (c) is laminating, (d) is exposure, (e) is development, (f) is electroplating, (g) is film stripping, and (h) is window opening;

[0020] Fig.10 It is a schematic diagram of the structure and pull-out test of a blind hole detection module of a 4-layer HDI circuit board in the prior art;

[0021] Fig.11 This is a schematic diagram of the blind hole pulling detection module structure and pulling test of Example 3 of the utility model. DETAILED DESCRIPTION

[0022] The present invention will be described in further detail below in conjunction with the accompanying drawings. Example 1

[0023] like Figures 2~4As shown in FIG. 1 , it is a preferred embodiment 1 of the method for preparing a blind hole pull-out detection module for an HDI circuit board of the utility model. The blind hole pull-out detection module is arranged in a non-product area of ​​an HDI circuit board with four or more circuit layers. For the convenience of description, the number of circuit layers of the HDI circuit board is recorded as n ,when n When it is singular, n The circuit layers are recorded from the inside to the outside as the first-level circuit layer 11, the second-level circuit layer 12, and the n +1 / 2 level circuit layer; when n When it is plural, n The circuit layers are recorded from the inside to the outside as level 1 circuit layers 11 to n / 2nd level circuit layer.

[0024] In this embodiment, a six-layer HDI circuit board is used to explain the blind hole pull-out detection module in detail. The HDI circuit board has a first-level circuit layer 11, a second-level circuit layer 12, and a third-level circuit layer 13 from the inside to the outside. The blind hole pull-out detection module includes a detection unit 2 for detecting the blind hole bonding force. In this embodiment, six such detection units 2 are included, and the number of detection units 2 can be appropriately increased according to actual application conditions.

[0025] Each detection unit 2 includes a detection blind hole 20 that connects different circuit layers. The detection blind hole 20 that connects the level 1 circuit layer 11 and the level 2 circuit layer 12 is recorded as a level 1-2 detection blind hole 22, and the detection blind hole 20 that connects the level 2 circuit layer 12 and the level 3 circuit layer 13 is recorded as a level 2-3 detection blind hole 23. The level 1 circuit layer 11 is the innermost circuit layer, and two level 1 circuit layers 11 are adjacent. In this embodiment, the two level 1 circuit layers 11 are connected by a through hole, so no 1-1 level detection blind hole is set.

[0026] In the existing conventional detection modules, such as Figure 1 As shown, the operator can only perform a direct pull-out test on the 2-3 level detection blind hole 23, i.e., the outermost detection blind hole 20, through the copper wire 7 and the solder ball 8, but cannot directly detect the 1-2 level detection blind hole 22 located on the inner side. This embodiment proposes an improved scheme, in which the above-mentioned 6 detection units 2 are arranged between circuit layers of different levels, and at least one detection unit 2 is arranged between each circuit layer of different levels. Specifically, the HDI circuit board can be divided into an upper half and a lower half, each of which has a level 1 circuit layer 11, a level 2 circuit layer 12, and a level 3 circuit layer 13. At least one detection unit 2 is arranged between the level 1 circuit layer 11 and the level 2 circuit layer 12, and between the level 2 circuit layer 12 and the level 3 circuit layer 13 of the upper half, and the lower half is the same as the upper half.

[0027] like Figure 2As shown, the detection blind hole 20 is filled with hole copper 31, and the hole copper 31 extends to the outside of the hole mouth of the detection blind hole 20 to form a surface copper 32. The bottom surface of the detection blind hole 20 is the inner copper 33. The hole copper 31 is combined with the inner copper 33. The surface copper 32 is a part of the relatively outer circuit layer among the different circuit layers conducted by the detection blind hole 20, and the inner copper 33 is a part of the relatively inner circuit layer among the circuit layers conducted by the detection blind hole 20. The surface copper 32 of each detection unit 2 is exposed. Taking the 1-2 level detection blind hole 22 as an example, its surface copper 32 is a part of the 2nd level circuit layer 12, and its inner copper 33 is a part of the 1st level circuit layer 11.

[0028] A window 4 is opened on the outside of the detection unit 2, so that the surface copper 32 of the detection unit 2 is exposed, so that the operator can directly perform a pull test on these detection units 2. At the same time, in order to avoid interference between the detection units 2, as a preferred embodiment, the detection units 2 are staggered on the HDI circuit board.

[0029] Compared with the prior art, the copper surface 32 of each detection unit 2 of the detection module of this embodiment is exposed, so the pull-out test can be performed on the detection blind holes 20 of any layer of the finished circuit board to ensure that the bonding force of the blind holes of each layer can be tested and verified, and the test is comprehensive. In addition, the detection module of this embodiment also has an advantage in the force direction during the test. The tested detection blind holes 20 are only subjected to the pull-out force in the vertical direction, without the interference of the lateral force, and the test results are more accurate.

[0030] The preparation method of the blind hole pulling detection module of this embodiment comprises the following steps:

[0031] S1, the circuit board is manufactured layer by layer according to the conventional process until a blind via is required.

[0032] S2, while making a conventional blind hole, make a detection blind hole 20 dedicated to checking the blind hole bonding force, then electroplate the entire circuit board to make the next circuit layer and detect the copper filling in the blind hole 20, the detection blind hole 20 connects the inner circuit layer with the outer circuit layer, and a detection blind hole 20 and its hole copper 31, the inner copper 33 on the bottom surface and the surface copper 32 formed outside the hole mouth together constitute a detection unit 2, specifically including the following sub-steps:

[0033] S2.1, drilling: as Figure 3 As shown in (a), a common blind hole and a detection blind hole 20 for conducting the level 1 circuit layer 11 and the level 2 circuit layer 12 are drilled. The detection blind hole is recorded as a level 1-2 detection blind hole 22. The level 1-2 detection blind hole is drilled in the non-product area of ​​the HDI circuit board and is arranged outside the level 1 circuit layer 11. The bottom surface of the level 1-2 detection blind hole 22 is inner copper 33, which is a part of the level 1 circuit layer 11;

[0034] S2.2, make the second level circuit layer: Figure 3 As shown in (b), a second-level circuit layer 12 is prepared on the outer side of the circuit board obtained after drilling, and a hole copper 31 is formed in the 1-2 level detection blind hole 22. The hole copper 31 is combined with the inner copper 33. The hole copper 31 extends to the outside of the hole mouth of the 1-2 level detection blind hole 22 to form a surface copper 32. The surface copper 32 of the 1-2 level detection blind hole 22 is a part of the second-level circuit layer.

[0035] S3, continue to make the circuit board layer by layer according to the conventional process, repeat step S2 whenever a blind hole needs to be made, and the subsequent circuit layer is always avoided outside the detection unit constructed in the previous order, which specifically includes the following sub-steps:

[0036] S3.1, drilling: as Figure 3 As shown in (c), the circuit board is continued to be manufactured and ordinary blind holes and detection blind holes 20 for conducting the level 2 circuit layer 12 and the level 3 circuit layer 13 are drilled. The detection blind hole is recorded as a level 2-3 detection blind hole 23. The level 2-3 detection blind hole 23 is drilled in the non-product area of ​​the HDI circuit board and is arranged outside the level 2 circuit layer 12. The inner copper 33 of the level 2-3 detection blind hole 23 is a part of the level 2 circuit layer 12.

[0037] S3.2, making a third-level circuit layer: prepare a third-level circuit layer 13 on the outer side of the circuit board obtained after drilling, specifically, copper deposition and dry film 6 ( Figure 3 (d)) Expose the non-line area ( Figure 3 (e)), removing the unexposed dry film 61 ( Figure 4 (f)), electroplating ( Figure 4 (g)), membrane removal ( Figure 4 (h)), copper removal; during the electroplating process, a hole copper 31 is formed in the 2-3 level detection blind hole 23, the hole copper 31 is combined with the inner copper 33, and the hole copper 31 extends to the outside of the hole mouth of the 2-3 level detection blind hole 23 to form a surface copper 32, the surface copper 32 of the 2-3 level detection blind hole 23 is a part of the 3-level circuit layer 13, and the circuit of the 2-3 level circuit layer 13 is avoided at the outside of the 1-2 level detection blind hole 22, so that the outside of the 1-2 level detection blind hole 22 is only covered by the insulating layer 5 but not by the circuit.

[0038] S4, after the preparation of four or more circuit layers is completed, Figure 4 As shown in (i), a window is opened on the outside of the detection unit 2 by laser peeling, and the obstruction is removed to expose the detection unit 2.

[0039] The detection blind via 20 needs to be exposed in the finished product stage, but since the production process requires the use of methods such as copper removal that have a corrosive effect on the pad, the detection blind via 20 cannot be exposed during the production process. The solution disclosed in the utility model not only provides a specific preparation method for the blind via pull-out detection module, but also ensures that the detection blind via 20 can be protected during the circuit board production process.

[0040] In addition to directly using the insulating layer 5 as protection, preferably, step S3.1 also includes: before continuing to make the circuit board, firstly sticking a protective tape on the outer side of the 1-2 level detection blind hole 22, and tearing off the protective tape after performing step S4.

[0041] Alternatively, before continuing to manufacture the circuit board, the outer side of the 1-2 level inspection blind hole 22 is first covered with hydrosol, and the hydrosol is dissolved and removed after performing step S4. Example 2

[0042] The difference between this embodiment and embodiment 1 is that the HDI circuit board of this embodiment has eight layers of circuits, such as Figures 6 to 9 As shown, from the inside to the outside, it includes 1st level circuit layer 11, 2nd level circuit layer 12 and 3rd level circuit layer 13, 3rd level circuit layer 13 and 4th level circuit layer 14, 2 layers each, and there are 8 detection units 2 in total.

[0043] In this embodiment, the eight detection units 2 are arranged between circuit layers of different levels, and each circuit layer of different levels is provided with at least one detection unit 2. Specifically, the HDI circuit board can be divided into an upper half and a lower half, each of which has one layer each of a level 1 circuit layer 11, a level 2 circuit layer 12, a level 3 circuit layer 13 and a level 4 circuit layer 14. In the upper half, at least one detection unit 2 is arranged between the level 1 circuit layer 11 and the level 2 circuit layer 12, between the level 2 circuit layer 12 and the level 3 circuit layer 13, and between the level 3 circuit layer 13 and the level 4 circuit layer 14. The lower half is the same as the upper half.

[0044] The detection blind hole 20 connecting the level 1 circuit layer 11 and the level 2 circuit layer 12 is recorded as the level 1-2 detection blind hole 22, the detection blind hole 20 connecting the level 2 circuit layer 12 and the level 3 circuit layer 13 is recorded as the level 2-3 detection blind hole 23, and the detection blind hole 20 connecting the level 3 circuit layer 13 and the level 4 circuit layer 14 is recorded as the level 3-4 detection blind hole 24. In the existing conventional detection module, Figure 5 As shown, the operator can only perform a direct pull-out test on the 3-4 level detection blind hole 24, that is, the outermost detection blind hole 20, but cannot directly test the 1-2 level detection blind hole 22 and the 2-3 level detection blind hole 23 located on the inner side.

[0045] The preparation method of the blind hole pulling detection module of this embodiment comprises the following steps:

[0046] S1~S3.2 are the same as in Example 1;

[0047] S3.3, drilling: Continue to make the circuit layers of the circuit board layer by layer until you need to make blind holes, such as Figure 7 As shown in (a), the insulating layer 5 is pressed on the outer side of the 3-level circuit layer 13, and then the Figure 7 (b) drilling ordinary blind holes and 3-4 level inspection blind holes 24 for inspecting the blind hole bonding strength in the insulating layer 5 by drilling. The 3-4 level inspection blind holes are drilled in the non-product area of ​​the HDI circuit board and are arranged outside the 3-level circuit layer 13. The inner copper 33 of the 3-4 level inspection blind holes 24 is part of the 3-level circuit layer 13;

[0048] S3.4, making a 4-level circuit layer: prepare a 4-level circuit layer 14 on the outer side of the circuit board obtained after drilling, specifically, copper deposition and dry film 6 ( Figure 7 (c) Expose non-line areas ( Figure 8 (d)), remove the unexposed dry film and retain the exposed dry film 61 ( Figure 8 (e)), electroplating ( Figure 8 (f)), membrane removal ( Fig. 9 (g) Copper removal: During the electroplating process, a hole copper 31 is formed in the 3-4 level detection blind hole 24, and the hole copper 31 is combined with the inner copper 33. The hole copper 31 extends to the outside of the hole of the 3-4 level detection blind hole 24 to form a surface copper 32. The surface copper 32 of the 3-4 level detection blind hole 24 is a part of the 4-level circuit layer 14. The circuit of the 4-level circuit layer 14 is avoided at the outside of the 1-2 level detection blind hole 22 and the 2-3 level detection blind hole 23, so that the outside of these detection blind holes 20 is only covered by the insulating layer 5 but not by the circuit;

[0049] S4 is the same as in Example 1, such as Fig. 9 As shown in (h), a window is opened on the outside of the detection unit 2 by laser peeling, and the obstruction is removed to expose the detection unit 2.

[0050] On this basis, HDI circuit boards with more circuit layers can also be prepared, just by repeating S2 (for example, S3.1 and S3.2 in Example 1 are a repetition of S2, and S3.3-S3.4 in this embodiment are another repetition of S2 based on the six-layer circuit board in Example 1) and avoiding the detection unit 2 constructed in the previous step until all circuit layers are processed. The detection blind hole 20 is not limited to connecting adjacent layers of circuit layers, but can also connect across layers, such as constructing a 2-4 level blind hole connecting the 2-level circuit layer and the 4-level circuit layer 14, or constructing a 1-4 level blind hole connecting the 1-level circuit layer and the 4-level circuit layer 14, etc. In addition, the detection blind hole 20 can also connect blind holes of the same level, such as constructing a 1-1 level blind hole connecting two adjacent 1-level circuit layers. The last situation will be described in detail in Example 3. Example 3

[0051] In this embodiment, Fig.11 As shown, the difference from Example 1 is that the HDI circuit board of this embodiment has four layers of circuits, including two layers of the first-level circuit layer 11 and two layers of the second-level circuit layer 12 from the inside to the outside. There are a total of four detection units 2 constructed through steps S1-S4. Specifically, the two innermost first-level circuit layers 11 of the HDI circuit board are adjacent, and two 1-1 level detection blind holes 21 connecting the two are arranged therebetween. The upper and lower parts of the circuit board each have a 1-2 level detection blind hole 22 connecting the first-level circuit layer 11 and the second-level circuit layer 12.

[0052] In the existing conventional detection modules, such as Fig.10 As shown, the operator can only perform a direct pull test on the 1-2 level detection blind hole 22, that is, the outermost detection blind hole 20, but cannot directly detect the 1-1 level detection blind hole located inside. The surface copper 32 of the detection unit 2 of this embodiment is exposed, so the operator can directly perform a pull test on these detection units 2.

Claims

1. A blind hole pulling detection module for HDI circuit board, characterized in that: The invention is arranged in a non-product area of ​​an HDI circuit board having four or more circuit layers, and comprises a detection unit (2) for detecting the bonding force of a blind hole. The detection unit (2) comprises a detection blind hole (20) for connecting inner and outer circuit layers to each other. The detection blind hole (20) is filled with hole copper (31). The hole copper (31) extends to the outside of the hole mouth of the detection blind hole (20) to form a surface copper (32). The bottom surface of the detection blind hole (20) is inner copper (33). The hole copper (31) is combined with the inner copper (33). The surface copper (32) is a part of the outer circuit layer connected by the detection blind hole (20). The inner copper (33) is a part of the inner circuit layer connected by the detection blind hole (20). The surface copper (32) of each detection unit (2) is exposed.

2. The blind hole pulling detection module according to claim 1, characterized in that: On the HDI circuit board, a window (4) is opened on the outer side of the detection unit (2), so that the surface copper (32) of the detection unit (2) is exposed.

3. The blind hole pulling detection module according to claim 2, characterized in that: The detection units (2) are arranged in a staggered manner on the HDI circuit board.

4. The blind hole pulling detection module according to claim 1, characterized in that: The HDI circuit board has n Layer line layer, when n When it is singular, n The circuit layers are sequentially recorded from the inside to the outside as the first circuit layer (11), the second circuit layer (12) to ( n +1) / 2 level circuit layer; when n When it is plural, n The circuit layers are recorded from the inside to the outside as the first circuit layer (11) to n / 2 level circuit layer; the detection unit (2) is arranged between circuit layers of different levels.

5. The blind hole pulling detection module according to claim 4, characterized in that: Each different level of circuit layer is provided with at least one detection unit (2).

6. The blind hole pulling detection module according to claim 5, characterized in that: The HDI circuit board has six layers of circuits, which include, from the inside to the outside, two layers each of a first-level circuit layer (11), a second-level circuit layer (12) and a third-level circuit layer (13), and at least one detection unit (2) is provided between the first-level circuit layer (11) and the second-level circuit layer (12), and between the second-level circuit layer (12) and the third-level circuit layer (13).

7. The blind hole pulling detection module according to claim 1, characterized in that: The HDI circuit board has eight layers of circuits, which include, from the inside to the outside, two layers each of a first-level circuit layer (11), a second-level circuit layer (12), a third-level circuit layer (13) and a fourth-level circuit layer (14); at least one detection unit (2) is provided between the first-level circuit layer (11) and the second-level circuit layer (12), between the second-level circuit layer (12) and the third-level circuit layer (13), and between the third-level circuit layer (13) and the fourth-level circuit layer (14).

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