Anti-copper wrinkle process of PCB board and PCB board

Abstract

The present invention relates to a copper wrinkle prevention process for a PCB board and a PCB board, and the copper wrinkle prevention process comprises the following steps: S1, etching a plurality of graphic units on a core board, wherein a gold finger area on one graphic unit is spaced from a gold finger area on an adjacent graphic unit, so that a gap area is formed between the gold finger areas of two adjacent graphic units, and a supporting copper layer is formed in the gap area; S2, stacking a plurality of core boards and a plurality of PP layers together in a set order, and pressing to form a composite board; S3, dividing the composite board and removing the gap area to form a plurality of PCB boards. By setting a supporting copper layer in the gap area, when pressing the composite board, the supporting copper layer can play a supporting role for the first core board and the third core board, avoiding the two gold finger areas on the second core board from being connected and forming a larger copper-free area, thereby avoiding the first core board and the third core board from being sunken toward the second core board during pressing to produce copper wrinkle defects.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board processing, and in particular to a copper wrinkle prevention process for a PCB board and a PCB board. Background Art

[0002] PCB (Printed Circuit Board) is also called printed circuit board, which is the carrier of electrical connection of electronic components. PCB can be divided into single-sided board, double-sided board and multi-layer board. Multi-layer board is made of multiple core boards pressed together to increase the wiring area of ​​the whole PCB board to meet the needs of graphic design. Multi-layer PCB is widely used at present.

[0003] like Figure 1 and Figure 2 As shown in FIG. 1 , in the manufacturing process of a multi-layer PCB board, several PCB boards are usually combined together for processing, and then divided after processing. Figure 2 For example, three core boards are provided, and the three core boards are respectively a first core board 1', a second core board 2' and a third core board 3' which are stacked from top to bottom. The core board includes a substrate layer and a copper foil layer covering the substrate layer, that is, the first core board 1' includes a first substrate layer 11' and a first copper foil layer 12', the second core board 2' includes a second substrate layer 21' and a second copper foil layer 22', and the third core board 3' includes a third substrate layer 31' and a third copper foil layer 32'. The core board is formed by an etching process to form a plurality of graphic units 101' corresponding to the PCB board one by one. The graphic unit 101' includes a gold finger area and a graphic circuit 103' for conducting circuits and signals formed by etching the copper foil layer. After the core board is manufactured, the three core boards are pressed together to form a composite board, and a PP layer 4' (PP, Polypropylene) is sandwiched between two adjacent core boards. The composite board is hot-pressed, and the PP layer is melted and filled into the copper-free area (i.e., the area where the copper foil layer is etched) on the core board. After the composite board is manufactured, the composite board is divided into a plurality of PCB boards along the dividing line 300'.

[0004] The prior art has the following deficiencies: On the composite board, the two adjacent PCB boards are respectively the first PCB board 100′ and the second PCB board 200′, and the two adjacent PCB boards are connected. On the second core board 2′, the first gold finger area 102′ corresponding to the first PCB board 100′ is a copper-free area, and the second gold finger area 202′ corresponding to the second PCB board 200′ is a copper-free area. The two copper-free areas are connected, so that a large blank space 400′ (two superimposed copper-free areas) is formed at the position where the two PCB boards are connected on the second core board 2′. During hot pressing, the copper-free areas corresponding to the two gold finger areas on the second core board 2′ cannot effectively support the first core board 1′ and the third core board 3′ on both sides due to insufficient filling (the PP layer 4′ melts and flows into the copper-free area). This causes the gold finger areas corresponding to the first core board 1′ and the third core board 3′ to be concave, and causes copper wrinkles (i.e., wrinkles in the copper foil layer) in the gold finger area and its surrounding area. Summary of the invention

[0005] One object of the present invention is to provide a copper wrinkle prevention process for a PCB board, which can support the outermost core board to avoid the occurrence of copper wrinkle defects.

[0006] Another object of the present invention is to provide a PCB board which can avoid copper wrinkle defects and is beneficial to improving product quality.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A copper wrinkle prevention process for a PCB board is provided, comprising the following steps:

[0009] Step S1, providing a core board, etching a plurality of graphic units on the core board, wherein a gold finger region on one of the graphic units is spaced from a gold finger region on an adjacent graphic unit, so that a gap region is formed between the gold finger regions of two adjacent graphic units, and a supporting copper layer is formed in the gap region;

[0010] Step S2, stacking a plurality of the core panels and a plurality of PP layers together in a set order, and pressing them together to form a composite panel;

[0011] Step S3, dividing the composite board and removing the gap area to form a plurality of PCB boards.

[0012] Furthermore, in step S1, the core board includes a substrate layer and a copper foil layer covering the substrate layer, and the copper foil layer is etched to form the graphic unit. During etching, the copper foil layer in the gap area is retained to form the supporting copper layer.

[0013] Furthermore, the gap area includes a main gap area and transition areas located on both sides of the main gap area, the transition area is located between the main gap area and the gold finger area, and the supporting copper layer is located in the main gap area. During etching, the copper foil layer in the transition area is removed to separate the supporting copper layer from the gold finger area.

[0014] Furthermore, in step S2, during the pressing, the composite board is heated to soften the PP layer and fill it into the gold finger area and the transition area.

[0015] Furthermore, the distance between the gold finger areas of two adjacent graphic units is 2 to 8 mm.

[0016] Furthermore, the thickness of the supporting copper layer is the same as the thickness of the graphic circuit in the graphic unit.

[0017] Furthermore, a plurality of the graphic units are arranged in a matrix on the core board, any two adjacent graphic units are spaced apart, and the supporting copper layer is formed between any two adjacent graphic units.

[0018] Furthermore, the gold finger areas in the same horizontal row or the same vertical column are aligned.

[0019] Furthermore, along the length direction of the composite board, the gold finger areas are distributed at both ends of the corresponding graphic units, and the spacing between two adjacent graphic units is L1. Along the width direction of the composite board, the spacing between two adjacent graphic units is L2, and L1>L2.

[0020] Also provided is a PCB board, which is manufactured by the above-mentioned PCB board anti-copper wrinkle process.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention discloses a copper wrinkle prevention process for a PCB board and a PCB board. The copper wrinkle prevention process is to set a supporting copper layer in the gap area between two adjacent graphic units, and use the supporting copper layer to separate the two connected gold finger areas, so that during hot pressing, the PP layer fills the copper-free areas of the two gold finger areas respectively. Compared with the connection of two copper-free areas, the space of a single copper-free area is smaller, which is conducive to the PP layer to smoothly fill each copper-free area. When the composite board is pressed, the supporting copper layer can support the first core board and the third core board, thereby preventing the gold finger area on the first core board and the gold finger area on the third core board from being sunken toward the second core board during pressing, thereby preventing the copper wrinkle defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a PCB board in the prior art.

[0024] Figure 2 It is a partial cross-sectional view of a composite plate in the prior art.

[0025] Figure 3 Schematic diagram of a composite plate according to an embodiment of the present invention.

[0026] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0027] Figure 5 It is a partial cross-sectional view of a composite plate according to an embodiment of the present invention.

[0028] Figure 6 FIG. 4 is a partial schematic diagram of a second core plate according to an embodiment of the present invention.

[0029] Figure 7 It is a partial schematic diagram of a second core plate according to another embodiment of the present invention.

[0030] Figure 1 and Figure 2 middle:

[0031] 1', first core board; 11', first substrate layer; 12', first copper foil layer; 2', second core board; 21', second substrate layer; 22', second copper foil layer; 3', third core board; 31', third substrate layer; 32', third copper foil layer; 4', PP layer;

[0032] 100', first PCB board; 101', graphic unit; 102', first gold finger area; 103', graphic circuit; 200', second PCB board; 202', second gold finger area; 300', dividing line; 400', blank space;

[0033] Figures 3 to 7 middle:

[0034] 1. First core board; 11. First substrate layer; 12. First copper foil layer; 2. Second core board; 21. Second substrate layer; 22. Second copper foil layer; 3. Third core board; 31. Third substrate layer; 32. Third copper foil layer; 4. PP layer; 5. Support copper layer; 6. Gap area; 7. Transition area;

[0035] 100, first PCB board; 101, first graphic unit; 102, first gold finger area; 200, second PCB board; 201, second graphic unit; 202, second gold finger area; 300, dividing line. DETAILED DESCRIPTION

[0036] In order to make the technical problem solved by the present invention, the technical solution adopted and the technical effect achieved more clearly, the technical solution of the present invention is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0037] like Figures 3 to 6 As shown, the present invention provides a copper wrinkle prevention process for PCB boards, which is used to manufacture PCB boards. Since the size of a single PCB board is small, in order to improve production efficiency, several PCB boards are combined together for manufacturing. The several PCB boards combined together and the scraps used for segmentation processing are collectively referred to as composite boards. After the composite board is manufactured, the composite board is segmented to form several PCB boards. The composite board before segmentation includes a plurality of core boards, and the core board includes a substrate layer and a copper foil layer covering the substrate layer. Graphic units corresponding to the PCB boards are formed on each core board by etching. Multi-layer PCB boards are mainly reflected in the corresponding number of core boards. For example, a three-layer PCB board has three layers of core boards, and a five-layer PCB board has five layers of core boards. After the etching of the core board is completed, the plurality of core boards are pressed together to form a composite board.

[0038] Figure 3 Schematic diagram of a composite board, on which a plurality of PCB boards are distributed. To facilitate the description of the anti-copper wrinkle process, this embodiment is described in detail by taking two adjacent PCB boards which are three-layer boards as an example.

[0039] The two adjacent PCB boards are respectively a first PCB board 100 and a second PCB board 200. The composite board before segmentation includes a first core board 1, a second core board 2 and a third core board 3 arranged in sequence from top to bottom. Among them, the first core board 1 includes a first substrate layer 11 and a first copper foil layer 12 covering the first substrate layer 11. The second core board 2 includes a second substrate layer 21 and a second copper foil layer 22 covering the second substrate layer 21. The third core board 3 includes a third substrate layer 31 and a third copper foil layer 32 covering the third substrate layer 31.

[0040] The anti-copper wrinkle process comprises the following steps:

[0041] Step S1, etching and forming a plurality of graphic units on three core boards respectively, and the plurality of graphic units correspond to a plurality of PCB boards one by one. The graphic units include various graphic circuits formed by the copper foil layer and a blank area (copper-free area) formed after the copper foil layer is removed. Specifically, the first PCB board 100 has three first graphic units 101, and the three first graphic units 101 are respectively located on three corresponding core boards. The end of the first graphic unit 101 has a first gold finger area 102. Among them, the first gold finger area 102 on the first core board 1 and the third core board 3 is a copper area (that is, the gold finger area is covered with copper foil), and the first gold finger area 102 on the second core board 2 is a copper-free area. The end of the second graphic unit 201 has a second gold finger area 202, and the first gold finger area 102 is adjacent to the second gold finger area 202. Among them, the second gold finger area 202 on the first core board 1 and the third core board 3 is a copper area, and the second gold finger area 202 on the second core board 2 is a copper-free area. When the graphic units on the core board are laid out, the first gold finger area 102 on the first graphic unit 101 is spaced from the second gold finger area 202 on the second graphic unit 201, so that a gap area 6 is formed between the first gold finger area 102 and the second gold finger area 202. A supporting copper layer 5 is formed in the gap area 6. The supporting copper layer 5 is the same copper foil as the graphic circuit. By providing the supporting copper layer 5 in the gap area 6, when the composite board is pressed, the supporting copper layer 5 can play a supporting role for the first core board 1 and the third core board 3, avoiding the two gold finger areas on the second core board 2 from being connected and forming a larger copper-free area, thereby avoiding the first core board 1 and the third core board 3 from being sunken toward the second core board 2 during pressing and causing copper wrinkle defects.

[0042] Step S2, stack the first core board 1, the second core board 2 and the third core board 3 from top to bottom, and a PP layer 4 is sandwiched between the first core board 1 and the second core board 2, and a PP layer 4 is sandwiched between the second core board 2 and the third core board 3. The number of core boards and the number and arrangement order of PP layers 4 can be adaptively selected according to the specific PCB board structure. The core board and the PP layer 4 are hot pressed to form a composite board. It can be understood that during the hot pressing process, as the temperature increases, the PP layer 4 softens and fills the copper-free area on the second core board 2. As the temperature continues to rise, the PP layer 4 is solidified and formed, and all the core boards are tightly combined together under the bonding action of the PP layer 4 to form a composite board. Of course, the copper-free area corresponding to the first gold finger area 102 and the second gold finger area 202 on the second core board 2 is also filled with the PP layer 4.

[0043] Step S3, drilling, copper deposition, gold plating, etc. are performed on the composite board. After the composite board is processed, the composite board is segmented, and the gap area 6 and the edges and corners located at the periphery of each PCB board are removed along the segmentation line 300 to segment and form several PCB boards.

[0044] It is understandable that the support copper layer 5 is not a component of the final product of the PCB board, but only plays a supporting role for the topmost and / or bottommost core board during the manufacturing process to avoid the problem of copper wrinkles caused by the depression of the gold finger area on the core board during hot pressing. After the manufacturing is completed, the support copper layer 5 will be removed. The support copper layer 5 can be directly made from the second copper foil layer 22 in the second core board 2, or it can be reset after the second core board 2 is etched.

[0045] Optionally, the supporting copper layer 5 is directly made from the second copper foil layer 22. When the second core board 2 is etched to form pattern units, the copper foil layer in the gap area 6 is retained to form the supporting copper layer 5.

[0046] Optionally, refer to Figure 4 As shown, the spacing between the first gold finger area 102 on the first PCB board 100 and the second gold finger area 202 on the second PCB board 200 is 2 to 8 mm. The thickness of the supporting copper layer 5 is the same as the thickness of the graphic circuit in the graphic unit, that is, the thickness of the supporting copper layer 5 is the same as the depth of the gold finger area on the second core board 2, so as to ensure the supporting effect of the supporting copper layer 5.

[0047] In another embodiment, referring to Figure 7 As shown, the gap area 6 includes a main gap area and transition areas 7 located on both sides of the main gap area, the supporting copper layer 5 is located in the main gap area, and the transition area 7 is located between the main gap area and the gold finger area. During etching, the copper foil layer in the transition area 7 is removed to space the supporting copper layer 5 from the first gold finger area 102, and the supporting copper layer 5 from the second gold finger area 202. It can be understood that the width of the supporting copper layer 5 is smaller than the width of the gap area 6, and there is a copper-free area between the supporting copper layer 5 and the adjacent graphic units. During lamination, the PP layer 4 can be filled into the gold finger area and the transition area 7 on the second core board 2. This structure can space the supporting copper layer 5 from the dividing line 300, so as to avoid the supporting copper layer 5 remaining in the edge area of ​​the single PCB board when the single PCB board is finally divided.

[0048] Optionally, refer to Figure 3 As shown, the composite board includes three core boards, and a number of graphic units corresponding to the PCB boards are distributed on each core board. The graphic units on each core board are arranged in a matrix, and along the horizontal direction of the core board (the Y direction shown in the figure), two adjacent graphic units are distributed at intervals, and along the vertical direction of the core board (the X direction shown in the figure), any two adjacent graphic units are distributed at intervals. A supporting copper layer 5 is formed between any two adjacent graphic units. It can also be understood that a supporting copper layer 5 is provided around each graphic unit. The supporting copper layer 5 around the graphic unit provides support during lamination to avoid copper wrinkles on the periphery of the PCB board.

[0049] Optionally, the gold finger areas on the same horizontal row or vertical column of the core board are aligned. It is understandable that after the composite board is processed, the scraps other than the graphic unit need to be removed. During processing, the gold finger areas on the same horizontal row or vertical column can be processed simultaneously, which is conducive to improving processing efficiency.

[0050] Optionally, along the length direction of the composite board (X direction shown in the figure), the gold finger area is distributed at both ends of the corresponding graphic unit. This structure can provide sufficient space between two adjacent graphic units located in the same vertical column to arrange the gap area 6, so as to facilitate the layout of several graphic units on the core board. Along the length direction of the composite board, the spacing between two adjacent graphic units is L1, and along the width direction of the composite board (Y direction shown in the figure), the spacing between two adjacent graphic units is L2, L1>L2. It can be understood that the gold finger area of ​​the PCB board will extend to the edge position of the graphic unit, and then the gold finger areas on the two adjacent graphic units on the second core board 2 are connected. The other graphic circuits on the graphic unit are all located inside the graphic unit, and there will be no situation where two copper-free areas are connected to form a larger blank space. Therefore, a gap area 6 with a larger spacing is set on the side of the two adjacent graphic units with the gold finger area to improve the utilization rate of the entire composite board.

[0051] It should be noted that the gold finger on the PCB is located on the first core board 1 and / or the third core board 3. Along the thickness direction of the PCB, the entire space corresponding to the gold finger is called the gold finger area. Figure 3 As shown, the first PCB board 100 has three first gold finger areas 102, and the three first gold finger areas 102 are respectively located on the first core board 1, the second core board 2 and the third core board 3. Among them, there is no actual gold finger on the second core board 2, so the first gold finger area 102 on the second core board 2 is not covered by a copper foil layer.

[0052] The significant effect of this embodiment is: the anti-copper wrinkle process sets a supporting copper layer 5 in the gap area 6 between two adjacent graphic units, and uses the supporting copper layer 5 to separate the two connected gold finger areas, so that the PP layer 4 fills the copper-free areas of the two gold finger areas respectively during hot pressing. Compared with the connection of two copper-free areas, the space of a single copper-free area is smaller, which is conducive to the smooth filling of each copper-free area by the PP layer 4. When the composite board is pressed, the supporting copper layer 5 can play a supporting role for the first core board 1 and the third core board 3, thereby preventing the gold finger area on the first core board 1 and the gold finger area on the third core board 3 from being sunken toward the second core board 2 during pressing, thereby preventing the copper wrinkle defect.

[0053] A PCB board is also provided, which is made by the above-mentioned anti-copper wrinkle process. By combining a plurality of PCB boards into a composite board for processing, it is beneficial to improve production efficiency. At the same time, by arranging a supporting copper layer 5 between the gold finger areas of two adjacent PCB boards, the supporting copper layer 5 plays a supporting role during pressing, thereby avoiding the occurrence of copper wrinkle defects in the outermost gold finger area, thereby improving the product quality of the PCB board.

[0054] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. A copper wrinkle prevention process for a PCB board, characterized in that: The following steps are involved: Step S1, providing a core board, etching a plurality of graphic units on the core board, wherein a gold finger region on one of the graphic units is spaced from a gold finger region on an adjacent graphic unit, so that a gap region is formed between the gold finger regions of two adjacent graphic units, and a supporting copper layer is formed in the gap region; Step S2, stacking a plurality of the core panels and a plurality of PP layers together in a set order, and pressing them together to form a composite panel; Step S3, dividing the composite board and removing the gap area to form a plurality of PCB boards; In step S1, the core board includes a substrate layer and a copper foil layer covering the substrate layer, and the copper foil layer is etched to form the graphic unit. During etching, the copper foil layer in the gap area is retained to form the supporting copper layer; The gap area includes a main gap area and transition areas located on both sides of the main gap area, the transition area is located between the main gap area and the gold finger area, the supporting copper layer is located in the main gap area, and during etching, the copper foil layer in the transition area is removed to space the supporting copper layer from the gold finger area; In step S2, during the pressing, the composite board is heated to soften the PP layer and fill it into the gold finger area and the transition area.

2. The process for preventing copper wrinkles of a PCB board according to claim 1, characterized in that: The distance between the gold finger areas of two adjacent graphic units is 2-8 mm.

3. The process for preventing copper wrinkles of a PCB board according to claim 1, characterized in that: The thickness of the supporting copper layer is the same as the thickness of the graphic circuit in the graphic unit.

4. The process for preventing copper wrinkles of a PCB board according to claim 1, characterized in that: A plurality of the graphic units are arranged in a matrix on the core board, any two adjacent graphic units are spaced apart, and the supporting copper layer is formed between any two adjacent graphic units.

5. The process for preventing copper wrinkles of a PCB board according to claim 4, characterized in that: The gold finger areas located in the same horizontal row or the same vertical column are aligned.

6. The process for preventing copper wrinkles of a PCB board according to claim 4, characterized in that: Along the length direction of the composite board, the gold finger areas are distributed at both ends of the corresponding graphic units, and the spacing between two adjacent graphic units is L1. Along the width direction of the composite board, the spacing between two adjacent graphic units is L2, and L1>L2.

7. A PCB board, characterized in that: The PCB board is manufactured by the anti-copper wrinkle process of any one of claims 1 to 6.

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