Circuit board pressing structure

Abstract

The utility model discloses a circuit board pressing structure, which comprises a mother board, the mother board is obtained by overlapping a plurality of daughter boards and prepregs, a preset position of an edge area of each daughter board is provided with a copper column bonding hole, and the copper column bonding hole comprises a first bonding hole and a second bonding hole which are arranged adjacently in pairs; the circuit board pressing structure further comprises solid copper columns in one-to-one correspondence with the copper column binding holes, copper caps are arranged at the rear ends of the solid copper columns, the solid copper columns comprise first copper columns and second copper columns, the first copper columns are embedded into the first binding holes through the front face of the mother board, and the second copper columns are embedded into the second binding holes through the back face of the mother board. The solid copper columns are not prone to deformation in the mother board pressing process, and copper scraps caused by rivet blooming can be avoided. On the other hand, the solid copper columns are embedded in the two adjacent copper column bonding holes from the positive direction and the negative direction respectively, and interlayer dislocation of the neutron plate in the pressing process can be effectively avoided. According to the scheme, the mother board can be bonded in advance and then fed to the pressing machine, the efficiency of the pressing process is improved, and the productivity of the pressing machine is improved.

Description

Technical Field

[0001] This utility model relates to the field of PCB (Printed Circuit Board) manufacturing technology, and in particular to a circuit board lamination structure. Background Technology

[0002] Driven by the three major trends of PCB miniaturization, high frequency and high speed, and high reliability, PCB products have balanced performance improvement and manufacturing costs through layer-addition processes, buried and blind via technology, and layer optimization. Sequential design has become the preferred solution for high-end electronic equipment manufacturers. However, alignment has become a challenge for the industry in this type of product. Currently, the bonding process for such high-multilayer products uses methods such as pinlam and fusion bonding, both of which have drawbacks to varying degrees.

[0003] 1. In the current industry, when riveting machines are used for riveting, stress in the X and Y directions is generated during the riveting and pressing processes. This can easily lead to misalignment between sub-plate layers, resulting in poor alignment.

[0004] 2. The characteristic of pin-lam positioning is that the pins used are of large diameter, and the layers are not easy to slip during the pressing process. It is currently the pressing method with better alignment in the industry, but its low efficiency has also become a bottleneck for the production capacity of some companies. Utility Model Content

[0005] This invention provides a circuit board lamination structure to solve the problem in the prior art where misalignment between sub-board layers easily occurs, resulting in poor alignment or good alignment but low efficiency.

[0006] This utility model provides a circuit board lamination structure, which includes a mother board, which is obtained by stacking multiple daughter boards and prepregs. Each daughter board and the prepreg are provided with copper pillar bonding holes at preset positions on the edge area of ​​each daughter board and the prepreg. The copper pillar bonding holes include a pair of adjacent first bonding holes and second bonding holes.

[0007] The circuit board lamination structure also includes solid copper pillars that correspond one-to-one with the copper pillar bonding holes. The rear end of each solid copper pillar is provided with a copper cap. Each solid copper pillar includes a first copper pillar and a second copper pillar. The first copper pillar is embedded in the first bonding hole through the front side of the motherboard, and the second copper pillar is embedded in the second bonding hole through the back side of the motherboard.

[0008] Optionally, the edge region of the sub-plate is further provided with fusion positioning holes and fusion position patterns.

[0009] Optionally, the diameter of the front end of the solid copper pillar is smaller than the diameter of the pillar body.

[0010] Optionally, the spacing between the paired first bonding hole and the second bonding hole is 2mm to 3mm.

[0011] Optionally, the distance from the copper pillar bonding hole to the edge of the sub-board is greater than 5mm.

[0012] Optionally, the difference between the diameter of the copper pillar bonding hole and the diameter of the solid copper pillar is in the range of 0.005mm to 0.025mm.

[0013] Optionally, the diameter of the solid copper column ranges from 3.15 mm to 3.17 mm.

[0014] Optionally, the diameter of the copper cap ranges from 5mm to 6mm.

[0015] Optionally, the thickness of the copper cap ranges from 0.5 mm to 0.8 mm.

[0016] Optionally, the length of the solid copper pillar accounts for 70% to 80% of the thickness of the mother plate.

[0017] The technical advantages of this invention are as follows: Replacing the hollow rivets in the prior art with solid copper pillars, which are less prone to deformation during the motherboard lamination process, avoids the problem of copper fragments caused by rivet breakage leading to internal shortness in the product, and significantly reduces interlayer misalignment of the sub-boards. Furthermore, embedding solid copper pillars from opposite directions into the bonding holes of two adjacent pillars effectively prevents horizontal and vertical misalignment of the sub-boards during lamination, thus avoiding interlayer misalignment. In addition, this invention allows for pre-bonding of the motherboard before pressing, improving the efficiency of the lamination process and increasing press capacity.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a top view of a sub-plate structure provided in an embodiment of this utility model;

[0021] Figure 2This is a partial cross-sectional schematic diagram of the motherboard in a circuit board pressing structure provided by an embodiment of the present invention;

[0022] Figure 3 This is a partial cross-sectional schematic diagram of a circuit board pressing structure provided in an embodiment of this utility model;

[0023] Figure 4 This is a schematic diagram of the structure of a solid copper column provided in an embodiment of this utility model.

[0024] Reference numerals: 10. Mother board; 11. Daughter board; 12. Prepreg; 111. First bonding hole; 112. Second bonding hole; 113. Fusion positioning hole; 114. Fusion position pattern; 21. First copper pillar; 22. Second copper pillar. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] The circuit board lamination structure of this embodiment includes a mother board, which is obtained by stacking multiple daughter boards and prepregs. The daughter boards and prepregs have the same shape and size. Copper pillar bonding holes are provided at preset positions on the edge areas of each daughter board and prepreg. The copper pillar bonding holes include a pair of adjacent first bonding holes and second bonding holes.

[0027] Figure 1 A top view of a sub-plate structure provided in an embodiment of this utility model, such as... Figure 1 As shown, copper pillar bonding holes are provided at preset positions in the edge region of the sub-board 11. The copper pillar bonding holes include a pair of adjacent first bonding holes 111 and second bonding holes 112, that is, the first bonding holes 111 and the second bonding holes 112 exist in pairs.

[0028] Figure 2 A partial cross-sectional schematic diagram of the motherboard in a circuit board lamination structure provided by an embodiment of this utility model is shown below. Figure 2 As shown, the motherboard 10 includes a daughterboard 11 and a prepreg layer 12, wherein the daughterboard 11 may include multiple daughterboards and the prepreg layer 12 may include multiple prepregs. Figure 1Only the copper pillar bonding holes at adjacent positions are shown, i.e. the gaps in the motherboard 10. The copper pillar bonding holes of each daughterboard 11 and prepreg 12 are set in the same position and number. After all the daughterboards 11 and prepregs 12 are aligned and stacked, the copper pillar bonding holes at the same position on each daughterboard 11 and prepreg 12 are aligned and connected in the vertical direction.

[0029] exist Figure 2 In the middle, will be located Figure 2 The through hole (copper pillar bonding hole) in the gap on the left serves as the first bonding hole 111, which will be located in Figure 2 The through hole (copper pillar bonding hole) in the gap on the right serves as the second bonding hole 112, which will be located in Figure 2 The top side, serving as the front of the motherboard 10, will be located on... Figure 2 One side of the bottom serves as the reverse side of the motherboard 10.

[0030] The circuit board lamination structure of this embodiment also includes solid copper pillars that correspond one-to-one with the copper pillar bonding holes. A copper cap is provided at the rear end of the solid copper pillar. The solid copper pillar includes a first copper pillar and a second copper pillar. The first copper pillar is embedded in the first bonding hole through the front side of the motherboard, and the second copper pillar is embedded in the second bonding hole through the back side of the motherboard.

[0031] Figure 3 This is a partial cross-sectional schematic diagram of a circuit board lamination structure provided in an embodiment of the present invention. Figure 3 The circuit board lamination structure in the middle is in Figure 2 Add solid copper pillars to the base plate, such as Figure 3 As shown, the solid copper pillar includes a first copper pillar 21 and a second copper pillar 22. The first copper pillar 21 is embedded in the first bonding hole 111 through the front side of the mother plate 10, and the second copper pillar 22 is embedded in the second bonding hole 112 through the back side of the mother plate 10.

[0032] pass Figures 1-3 The diagram illustrates the arrangement of two adjacent copper pillar bonding holes and the embedding method of two solid copper pillars. The diameter of the solid copper pillars should be slightly smaller than the diameter of the copper pillar bonding holes. This reduces the resistance encountered when the solid copper pillars are embedded in the copper pillar bonding holes, preventing pressure on the edges of the bonding holes and damage to the sub-board 11 (which typically carries various circuit components). During lamination, the solid copper pillars restrict the horizontal movement of the sub-board 11. Furthermore, copper caps are provided at the rear ends of the solid copper pillars. With the two solid copper pillars arranged in opposite directions, the first copper pillar 21 restricts the vertical upward displacement of the sub-board 11, and the second copper pillar 22 restricts the vertical downward displacement of the sub-board 11. In summary, this effectively prevents interlayer misalignment of the sub-board 11 during lamination.

[0033] The technical advantages of this invention are as follows: Replacing the hollow rivets in the prior art with solid copper pillars, which are less prone to deformation during the motherboard lamination process, avoids the problem of copper fragments caused by rivet breakage leading to internal shortness in the product, and significantly reduces interlayer misalignment of the sub-boards. Furthermore, embedding solid copper pillars from opposite directions into the bonding holes of two adjacent pillars effectively prevents horizontal and vertical misalignment of the sub-boards during lamination, thus avoiding interlayer misalignment. In addition, this invention allows for pre-bonding of the motherboard before pressing, improving the efficiency of the lamination process and increasing press capacity.

[0034] In an optional embodiment, such as Figure 1 As shown, the edge area of ​​the sub-board 11 is also provided with fusion positioning holes 113 and fusion position patterns 114. During the PCB manufacturing process, the fusion positioning holes 113 are used to physically position the PCB during the fusion process. The fusion position patterns 114 are used to fix various electronic components to the printed circuit board. Through the strong adhesive effect provided by the fusion position patterns 114, the components are ensured to be firmly fixed on the printed circuit board, preventing them from falling off during transportation or use.

[0035] In an optional embodiment, the diameter of the front end of the solid copper pillar is smaller than the diameter of the body of the solid copper pillar. Figure 4 This is a schematic diagram of the structure of a solid copper column. Figure 4 Figure (a) shows the front and side views of the solid copper column, and Figure (b) shows the top view of the solid copper column (with the front end as the top). A is the copper cap at the tail of the solid copper column, B is the column body, and C is the front end. As shown in Figures (a) and (b), the diameter of the front end C of the solid copper column is smaller than the diameter of the column body B. Optionally, the front end C of the solid copper column can be designed with an arc, with the diameter decreasing sequentially from the end in contact with the column body to the end away from the column body. That is, the front and side views of the front end C of the solid copper column are both isosceles trapezoids. This design allows the front end C of the copper column to have a smooth, rounded surface, which can serve as the starting point for embedding the solid copper column and guide the column body B of the solid copper column smoothly into the bonding hole of the copper column.

[0036] In an optional embodiment, the distance between the paired first bonding hole and the second bonding hole is 2mm to 3mm. The specific hole spacing can be set according to actual needs and is not limited thereto.

[0037] In an optional embodiment, the distance from the copper pillar bonding hole to the edge of the sub-board is greater than 5mm. When the solid copper pillar is embedded in the copper pillar bonding hole, the sub-board material around the copper pillar bonding hole will be subjected to stress. If the distance from the copper pillar bonding hole to the edge of the sub-board is too small, the stress on the material per unit area will increase, which may cause the edge of the sub-board to bear a large stress and crack.

[0038] In an optional embodiment, the difference between the diameter of the copper pillar bonding hole and the diameter of the solid copper pillar ranges from 0.005 mm to 0.025 mm. That is, setting the diameter of the copper pillar bonding hole to be slightly larger than the diameter of the solid copper pillar can avoid excessive compression of the sub-board material by the copper pillar bonding hole.

[0039] In one optional embodiment, the diameter of the solid copper pillar ranges from 3.15mm to 3.17mm. The specific diameter of the solid copper pillar is set according to actual needs and is not limited thereto.

[0040] In one optional embodiment, the diameter of the copper cap ranges from 5mm to 6mm, and the thickness ranges from 0.5mm to 0.8mm. The diameter and thickness of the copper cap can be set according to actual needs, with the criteria of not being easily broken and being able to bond firmly with the sub-board.

[0041] In one optional embodiment, the length of the solid copper pillar accounts for 70% to 80% of the thickness of the motherboard. The longer the solid copper pillar, the more sub-boards it can contact, thus restricting the horizontal movement of more sub-board layers (heights). Two solid copper pillars embedded into the motherboard from opposite directions further restrict the horizontal movement of each sub-board layer. Since the solid copper pillars need to be drilled away during later manufacturing processes, to reduce the difficulty and time of drilling, this embodiment does not set the length of the solid copper pillar to 100% of the motherboard thickness. Instead, this thickness percentage is set by comprehensively considering the solid copper pillar's ability to restrict the horizontal movement of the sub-boards and its obstruction to the drilling process.

[0042] In an optional embodiment, the solid copper pillar is made of a nickel-copper alloy.

[0043] In one optional embodiment, the copper pillar bonding holes are symmetrical both horizontally and vertically on the sub-board. Furthermore, different pairs of copper pillar bonding holes can be arranged at fixed intervals, allowing for relatively balanced stress distribution across the copper pillar bonding holes at various locations on the sub-board.

[0044] The main manufacturing process of the circuit board lamination structure of this utility model in circuit board manufacturing is as follows:

[0045] 1. Sub-board processing

[0046] This involves completing some of the customer's required wiring, mechanical blind vias, and the thickness of the hole copper and surface copper. In addition to the customer's required graphics within the unit, the sub-board edge also needs to be designed with fusion positioning holes, fusion position graphics, and copper pillar bonding holes. The spacing between two adjacent holes is generally 2mm to 3mm, and the distance from the hole to the board edge is ≥5mm but does not enter the unit (e.g., ...). Figure 1 (As shown).

[0047] 2. Prepreg processing

[0048] Drill copper pillar bonding holes of the same size and position as the sub-board design on the prepreg.

[0049] 3. Motherboard processing

[0050] First, the sub-board and the prepreg are preheated and fused together. Then, solid copper pillars are embedded in the specific copper pillar bonding holes on both sides of the hot-melted motherboard to bond the front and back sides. The length of the solid copper pillars should be designed to be between 70% and 80% of the overall board thickness.

[0051] 4. Drilling

[0052] This process mainly involves using mechanical drilling to remove the copper pillars, preventing chemical residue from causing poor quality in subsequent processes.

[0053] The process is illustrated using a 24L board (N+N structure):

[0054] S1 and N layer sub-board manufacturing process:

[0055] Material cutting inner layer drawing transfer → inner layer AOI (automatic optical inspection) → lamination → drilling → electroplating → outer layer circuit → outer layer AOI → supporting center;

[0056] S2. Motherboard manufacturing process:

[0057] Browning → Hot melting → Copper pillars on both sides → Panel layout → Pressing → Drilling → Electroplating → Outer layer pattern transfer → Outer layer AOI → Solder resist → Uncapping → Surface treatment → Shape → Electrical testing → FQC (Final Quality Control).

[0058] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.

[0059] The specific embodiments described above do not constitute a limitation on the scope of protection of this 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 principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A circuit board lamination structure, characterized in that, The circuit board lamination structure includes a mother board, which is obtained by stacking multiple daughter boards and prepregs. Each daughter board and prepreg are provided with copper pillar bonding holes at preset positions on the edge area. The copper pillar bonding holes include a pair of adjacent first bonding holes and second bonding holes. The circuit board lamination structure also includes solid copper pillars that correspond one-to-one with the copper pillar bonding holes. The rear end of each solid copper pillar is provided with a copper cap. Each solid copper pillar includes a first copper pillar and a second copper pillar. The first copper pillar is embedded in the first bonding hole through the front side of the motherboard, and the second copper pillar is embedded in the second bonding hole through the back side of the motherboard.

2. The circuit board lamination structure as described in claim 1, characterized in that, The edge area of ​​the sub-plate is also provided with fusion positioning holes and fusion position patterns.

3. The circuit board lamination structure as described in claim 1, characterized in that, The diameter of the front end of the solid copper pillar is smaller than the diameter of the pillar body.

4. The circuit board lamination structure as described in claim 1, characterized in that, The distance between the paired first bonding hole and the second bonding hole is 2mm to 3mm.

5. The circuit board lamination structure as described in any one of claims 1-4, characterized in that, The distance from the copper pillar bonding hole to the edge of the sub-plate is greater than 5mm.

6. The circuit board lamination structure as described in any one of claims 1-4, characterized in that, The difference between the diameter of the bonding hole of the copper pillar and the diameter of the solid copper pillar is in the range of 0.005mm to 0.025mm.

7. The circuit board lamination structure as described in claim 6, characterized in that, The diameter of the solid copper column ranges from 3.15 mm to 3.17 mm.

8. The circuit board lamination structure as described in claim 7, characterized in that, The diameter of the copper cap ranges from 5mm to 6mm.

9. The circuit board lamination structure as described in claim 8, characterized in that, The thickness of the copper cap ranges from 0.5 mm to 0.8 mm.

10. The circuit board lamination structure according to any one of claims 1-4, characterized in that, The length of the solid copper column accounts for 70% to 80% of the thickness of the mother plate.

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