CN116347798A

CN116347798A - Cover film replacement structure and replacement process for back surface of gold finger of multilayer FPC board

Info

Publication number: CN116347798A
Application number: CN202310332287.7A
Authority: CN
Inventors: 黄庆; 吴琼; 郝思文
Original assignee: Shenzhen Xindahui Flex Circuit Technology Co ltd
Current assignee: Shenzhen Xindahui Flex Circuit Technology Co ltd
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-06-27

Abstract

The invention relates to a cover film replacement structure and a process for the back of a golden finger of a multilayer FPC board, wherein the cover film replacement process comprises the following steps: manufacturing an inner layer circuit of the multi-layer FPC board, laminating a single-layer FPC board on a circuit layer of the multi-layer FPC board, and uncovering a part corresponding to a bending region of the circuit layer on the single-layer FPC board. By adopting the structure and the process for pressing the single-layer FPC board on the circuit layer of the multi-layer FPC board to replace the cover film to serve as the lower cover layer, on one hand, the influence that the cover film is used for uncovering and then processing the bent area high-level steps formed by the circuit and the circuit open circuit is easy to generate and the superfine circuit is unfavorable to be produced due to the high-level steps is eliminated; on the other hand, the single-layer FPC board has the functions of protecting and supporting the circuit by the lower cover layer, reinforcing the golden finger and adding one layer of circuit through the single-layer FPC board, so that the design of the internal circuit of the single-layer multi-layer FPC board is reduced, the thickness of the bending area is thinned, the bending bonding performance is improved, the material cost of the cover film is reduced, and the production flow is reduced and optimized.

Description

Cover film replacement structure and replacement process for back surface of gold finger of multilayer FPC board

Technical Field

The invention relates to the technical field of FPC production, in particular to a cover film replacement structure and a replacement process for the back of a golden finger of a multilayer FPC board.

Background

In the production process of the multilayer FPC board, the back of the golden finger needs to be adhered with a covering film to effectively prevent wrinkles in the processing process and ensure the product quality. For convenience in bending and binding a module product of the FPC board, a bending area beside the golden finger is often ultrathin, so that after the cover film corresponding to the bending area is covered on the back of the golden finger, a high-level step larger than 27.5um (cover film) +12.5um (pure glue) is formed between the bending area and the surface of a circuit layer on the back of the golden finger, on one hand, the circuit layer is easy to generate a circuit open circuit in the production process due to the high-level step, and on the other hand, a thick dry film manufacturing circuit larger than or equal to 30um is needed at the window opening of the cover film due to the high-level step, so that the circuit resolution is reduced, and the production of the superfine circuit is unfavorable.

Disclosure of Invention

In order to solve the defects that in the production process of the multi-layer FPC board, high-level steps exist between bending curves and the surface of a circuit layer on the back of a golden finger, so that circuit open circuits are easy to generate and superfine circuits are unfavorable to produce in the prior art, the invention provides a solution that a single-sided FPC board is attached to the circuit layer on the back of the golden finger of the multi-layer FPC board, and then a cover is opened on the single-sided FPC board corresponding to a bending area to replace a covering film structure in the prior art, so that the high-level steps are eliminated.

The technical scheme adopted for solving the technical problems is as follows:

in a first aspect, the present invention provides a cover film replacement structure for a back surface of a golden finger of a multi-layer FPC board, where the laminated structure of the multi-layer FPC board includes an upper cover layer, a circuit layer and a lower cover layer laminated in sequence, and the partition structure includes an inner circuit area, a bending area and a golden finger area adjacent in sequence, and the upper cover layer corresponding to the golden finger area is windowed to expose the golden finger to bond an external module, and the cover film replacement structure is as follows: the circuit layer of the inner layer circuit is manufactured on the back of the golden finger, the single-layer FPC board is pressed to serve as a lower cover layer of the multi-layer FPC board, the cover is opened at the part, corresponding to the bending area, of the single-layer FPC board, the single-side FPC board replaces the cover film to provide support protection for the circuit board manufacturing process and subsequent assembly and to provide reinforcement protection for the golden finger, the high-order step influence generated by the cover film in the bending area is eliminated, the product precision and yield of the multi-layer FPC are improved, and the process flow is reduced.

Preferably, the shape and size of the single-layer FPC board are consistent with those of the multi-layer FPC board, the copper foil surface of the single-layer FPC board faces the golden finger area and the PI surface faces outwards, the copper foil surface of the single-layer FPC board and the circuit layer of the manufactured inner circuit are pressed together through pure glue, and the copper foil layer and the PI surface of the single-layer FPC board bear the covering protection and the insulation protection and simultaneously have the reinforcing function on the golden finger.

Preferably, the circuit is manufactured on the copper foil layer of the single-layer FPC board before lamination, so that the single-layer FPC board has the protection and reinforcement functions, and meanwhile, the manufacturing of the inner circuit of one layer can be reduced, the bending area is reduced, and the subsequent bending and assembling performances are improved.

Preferably, the pure glue corresponding to the bending region is windowed before lamination, so that damage to the bending region due to too deep cutting is reduced when the single-sided FPC board corresponding to the bending region is deeply uncapped.

Preferably, the uncapped portion of the inflection region exposes the ink layer.

In a second aspect, the present invention also provides a cover film replacement process for the back of a gold finger of a multi-layer FPC board, which includes the steps of: manufacturing an inner layer circuit, and manufacturing circuits of an inner circuit area, a bending area and a golden finger area which are adjacent in sequence on a circuit layer of the multi-layer FPC board; laminating a single-layer FPC board, and laminating the multi-layer FPC board, the pure glue and the single-layer FPC board which are manufactured with inner-layer circuits in sequence, wherein the circuit surface of the golden finger back of the multi-layer FPC board and the copper foil surface of the single-layer FPC board are placed towards the pure glue; the cover is opened at the bending area, the cover is opened at the part corresponding to the bending area on the pressed single-layer FPC board, the cover film replacing structure on the back of the golden finger is formed on the single-layer FPC board, the whole FPC board is attached to the back of the circuit layer of the multi-layer FPC board to replace the lower cover layer, the influence of high-level steps of the bending area caused by using the cover film is eliminated, and the technological process and the material cost for manufacturing the cover film are reduced.

Preferably, the single-layer FPC board is in conformity with the size of the multi-layer FPC board so that the lower cover layer constituted by the single-layer FPC board has the functions of supporting protection, insulating protection, and reinforcement at the same time.

Preferably, before the single-sided FPC board is laminated, the method further comprises the steps of: the single-layer FPC board circuit is manufactured, the outermost inner circuit on the back of the golden finger of the multi-layer FPC board is formed, the single-sided FPC board has the functions of supporting protection and reinforcement, and the inner circuit is additionally arranged on the single-sided FPC board, so that the manufacturing process of the inner circuit of the single-layer multi-layer FPC board can be reduced, the thickness of the bending area is reduced by reducing the circuit of the bending area, and the subsequent bending bonding performance is improved.

Preferably, before the single-sided FPC board is laminated, the method further includes the steps of: and windowing the pure glue corresponding to the bending region, so that the damage to the bending region due to too deep cutting when the cover is opened by the single-sided FPC board corresponding to the bending region is reduced.

Before the single-layer FPC board is pressed, an ink layer is coated on the surface of the bending area of the manufactured inner layer circuit, and the manufactured inner layer circuit of the bending area is protected.

The beneficial effects of the invention include: according to the invention, the circuit layer of the single-layer FPC board is pressed on the multi-layer FPC board to replace the covering film to be used as the lower covering layer, on one hand, the high step capacity of the bending area formed by the covering film after the cover film is firstly processed and then the circuit is processed is eliminated by adopting the mode that the circuit is firstly processed and then the cover of the single-layer FPC board is opened corresponding to the bending area, the influence of easy open circuit and adverse production of superfine circuit caused by the high step is avoided, and the product yield and precision are improved; on the other hand, the structure of the cover film is replaced by the single-layer FPC board, and the circuit is manufactured on the copper foil layer of the single-layer FPC board, so that the single-layer FPC board has the functions of protecting and supporting the circuit by the lower cover layer, protecting and insulating the circuit, reinforcing the golden finger and adding one-layer inner circuit through the single-sided FPC board, and further, the thickness of a bending area is reduced by reducing the manufacturing of one-layer inner circuit, the material cost of the cover film is reduced, and the production flow is reduced and optimized.

Drawings

FIG. 1 is a schematic diagram of a cover film replacement structure on the back of a gold finger of a multi-layer FPC board provided by an embodiment of the invention;

fig. 2 is a flowchart of a process for replacing a cover film on the back of a gold finger of a multi-layer FPC board according to an embodiment of the present invention.

Reference numerals: 100-a multi-layer FPC board; 1-an upper cover layer; 2-a circuit layer; 3-a lower cover layer; 4-an ink layer; 5-an internal wiring area; 6-bending area; 7-golden finger area; 8-a single-layer FPC board; 9-copper foil surface; 10-PI; 11-pure glue; 12-windowing with pure rubber; 13-cover opening of single-sided FPC board.

Detailed Description

The invention is further described below with reference to the drawings and detailed description.

Referring to fig. 1, the invention provides a cover film replacement structure for the back of a golden finger of a multi-layer FPC board, the laminated structure of the multi-layer FPC board (100) comprises an upper cover layer (1), a circuit layer (2) and a lower cover layer (3) which are laminated in sequence, the partition structure of the multi-layer FPC board comprises an inner circuit area (5), a bending area (6) and a golden finger area (7) which are adjacent in sequence, the upper cover layer (1) corresponding to the golden finger area (7) is windowed to expose golden fingers to bond an external module, and the cover film replacement structure is as follows: and pressing a single-layer FPC board (8) on the circuit layer (2) with the inner layer circuit manufactured on the back of the golden finger to serve as a lower cover layer (3) of the multi-layer FPC board (100), and uncovering the part, corresponding to the bending region (6), on the single-layer FPC board (8), so that the bending region (6) is exposed through the single-sided FPC board uncovering (13).

Specifically, in the conventional production process, the lower cover layer (3) adopts a cover film to play a supporting and protecting role in the production process of the circuit board, the cover film is covered on the bending area (3) after being attached, and then the circuit processing is further carried out, so that a high-level step is generated in the bending area (3), on one hand, the circuit is easy to open, on the other hand, a thick dry film production circuit is required to be attached, the thick dry film is unfavorable for producing an ultrafine circuit, and the precision requirement of the current mainstream market on the circuit board is not met. Based on the method, a scheme of replacing a cover film with a single-layer FPC board (8) is provided, inner-layer circuit manufacture of the multi-layer FPC board (100) is performed, then the single-layer FPC board (8) is pressed and the circuit is further manufactured, and then the cover of the corresponding part of the bending area (6) on the single-layer FPC board (8) is opened, so that the influence of the cover film cover opening on the high-level step generated by the bending area (6) is eliminated, and the circuit manufacture yield and circuit precision of the multi-layer FPC board (100) are improved. The inner layer circuit of the multi-layer FPC board (100) includes a multi-layer circuit.

Further, the shape and the size of the single-layer FPC board (8) are consistent with those of the multi-layer FPC board (100), the copper foil surface (9) of the single-layer FPC board (8) faces the golden finger area (7) and the PI surface (10) outwards, and the copper foil surface (9) of the single-layer FPC board (8) is pressed with the circuit layer (2) of the manufactured inner-layer circuit through the pure glue (11).

Specifically, the single-layer FPC board (8) comprises a copper foil layer and a PI layer, when the single-layer FPC board is pressed, the copper foil layer faces inwards, the PI layer faces outwards, and the shape and the size of the single-layer FPC board (8) are consistent with those of the multi-layer FPC board (100), so that the single-layer FPC board has the functions of supporting protection and insulating protection, and simultaneously has the reinforcing function on a golden finger area.

Further, the circuit is manufactured on the copper foil layer of the single-layer FPC board (8) before lamination, so that when the inner-layer circuit of the multi-layer FPC board (100) is manufactured, the production flow for manufacturing one-layer circuit can be reduced, meanwhile, the thickness of the bending area (6) is reduced, and the bending bonding performance of the multi-layer FPC board (100) is improved.

Further, before lamination, the pure glue corresponding to the bending area (6) is windowed (12).

Specifically, after the circuit is pressed and further manufactured, the part, corresponding to the bending area (6), of the single-layer FPC board (8) is uncovered to expose the bending area (6), and as the depth control precision of the uncovering is not easy, the uncovering cannot be successfully completed if the depth is too shallow, the ink layer (4) or the circuit of the bending area (6) is easily cut if the depth is too deep, and the pure glue corresponding to the bending area (6) can avoid the adverse effect of too shallow or too deep control depth when the pure glue is windowed before pressing.

Further, the ink layer (4) is exposed at the uncapped part of the bending region (6).

Specifically, before laminating a single-layer FPC board (8), an ink layer (4) is coated on a bending region (6) where an internal circuit is manufactured to protect the circuit. It should be noted that, because of the bending performance requirement of the bending region (6), the bending bonding can be better realized by adopting the ink as the covering layer on both sides of the bending region (6).

Further, after the pure glue corresponding to the bending area (6) is windowed, the method can further comprise the step of placing a window filling block at the windowed position, and the functions comprise: the phenomenon that dislocation or pure glue overflows to a bending area when pressing is caused by the existence of a window opening blank area is prevented, and the bending area can be further prevented from being cut due to the fact that the cover is opened too deeply. The plug block may be a PI block or a copper block.

Referring to fig. 2, the invention further provides a process for replacing a cover film on the back of a gold finger of a multi-layer FPC board, comprising the following steps: manufacturing an inner layer circuit, and manufacturing circuits of an inner circuit area, a bending area and a golden finger area which are adjacent in sequence on a circuit layer of the multi-layer FPC board; laminating a single-layer FPC board, and laminating the multi-layer FPC board, the pure glue and the single-layer FPC board which are manufactured with inner-layer circuits in sequence, wherein the circuit surface of the golden finger back of the multi-layer FPC board and the copper foil surface of the single-layer FPC board are placed towards the pure glue; and (3) uncovering the bending area, uncovering the part, corresponding to the bending area, of the pressed single-layer FPC board, and forming a cover film replacement structure on the back of the golden finger by the single-layer FPC board after uncovering.

Specifically, when manufacturing the inner layer circuit of the multi-layer FPC board, the multi-layer circuit is manufactured, wherein the number of circuit layers of the bending region and the golden finger region is less than or equal to the number of circuit layers of the inner circuit region, because the thickness of the bending region is required to be thinner to improve the bending performance of the bending region. Before the cover is opened at the bending area after the single-layer FPC board is pressed, the circuit of the multi-layer FPC board can be further manufactured, and the single-layer FPC board can provide supporting protection, insulating protection and reinforcing functions. At this time, the bending area does not generate high-level steps due to uncovering, so that the yield and the precision of circuit manufacturing are improved. The single-sided FPC board is used for replacing the covering film, so that adverse effects of high steps generated by windowing of the covering film on circuit manufacture are eliminated, the production cost of the covering film is further saved, and the process flow is optimized and precisely decelerated.

Further, the single-layer FPC board is identical to the multi-layer FPC board in size.

Specifically, the single-layer FPC board composed of the copper foil layer and the PI layer can support, protect and insulate the manufactured circuit and protect the subsequent circuit manufacture.

Further, before laminating the single-sided FPC board, the method further comprises the steps of: and manufacturing a single-layer FPC board circuit to form an outermost inner circuit on the back of the golden finger of the multi-layer FPC board.

Specifically, under the condition that the supporting protection, insulation protection and reinforcement protection effects of the single-sided FPC board are not affected, the copper foil layer is manufactured into a circuit, so that one layer of circuit can be manufactured less when the multilayer FPC board produces an internal circuit, the process flow is reduced, the thickness of a bending area is thinned, and the subsequent bending bonding performance of the multilayer FPC board is improved.

Further, before the single-sided FPC board is laminated, the method further comprises the steps of: and windowing the pure glue corresponding to the bending area.

Specifically, the pure glue in the bending area is pre-windowed before being pressed, namely, the conventional front cover opening process is divided into two steps: the pure glue contacting the bending area is pre-windowed before pressing, and after pressing, the single-layer FPC board is uncapped, so that the accuracy of uncapping the single-sided FPC board and windowing the pure glue can be controlled more accurately, and the defect of products generated by over-deep uncapping or over-shallow uncapping of the front uncapping process is avoided.

Further, after the pure glue corresponding to the bending area is windowed, the method can further comprise the step of placing a window filling block at the windowed position, and the functions comprise: the phenomenon that dislocation or pure glue overflows to a bending area when pressing is caused by the existence of a window opening blank area is prevented, and the bending area can be further prevented from being cut due to the fact that the cover is opened too deeply. The plug block may be a PI block or a copper block.

Further, before the single-layer FPC board is pressed, an ink layer is coated on the surface of the bending area of the manufactured inner layer circuit.

Specifically, after the bending region route is manufactured, before the single-sided FPC board is pressed, the two sides of the bending curve can be coated with ink layers to serve as covering layers, the manufactured bending region route can be protected in the subsequent production process, and meanwhile, the ink layers can better realize bending bonding performance in the subsequent bending bonding and using processes of the multi-layer FPC board.

It will be apparent to those skilled in the art from this disclosure that various other changes and modifications can be made which are within the scope of the invention as defined in the appended claims.

It should be noted that: the embodiments described above are only some, but not all, embodiments of the invention. As used in the examples and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Claims

1. The laminated structure of the multilayer FPC board comprises an upper cover layer, a circuit layer and a lower cover layer which are laminated in sequence, wherein the partition structure comprises an inner circuit area, a bending area and a golden finger area which are adjacent in sequence, the upper cover layer corresponding to the golden finger area is windowed to expose golden fingers to bond an external module,

the cover film replacement structure is as follows: and pressing a single-layer FPC board on the circuit layer of the inner layer circuit manufactured on the back of the golden finger to serve as a lower cover layer of the multi-layer FPC board, and uncovering the part, corresponding to the bending region, on the single-layer FPC board.

2. The cover film replacement structure of the back of the golden finger of the multilayer FPC board according to claim 1, wherein the shape and the size of the single-layer FPC board are consistent with those of the multilayer FPC board, the copper foil surface of the single-layer FPC board faces towards the golden finger area and the PI surface faces outwards, and the copper foil surface of the single-layer FPC board is pressed with the circuit layer of the manufactured inner circuit through pure glue.

3. The cover film replacement structure for the back of the gold finger of the multi-layer FPC board according to claim 2, wherein a circuit is made on the copper foil layer of the single-layer FPC board before lamination.

4. The cover film replacement structure for the back of the golden finger of the multi-layer FPC board according to claim 2, wherein the pure glue corresponding to the bending area is windowed before lamination.

5. The cover film replacement structure for the back of a gold finger of a multi-layer FPC board according to claim 1, wherein after the cover is opened at a portion of the single-layer FPC board corresponding to the bending region, the bending region exposes the ink layer.

6. A cover film replacement process for the back of a golden finger of a multilayer FPC board is characterized by comprising the following steps:

manufacturing an inner layer circuit, and manufacturing circuits of an inner circuit area, a bending area and a golden finger area which are adjacent in sequence on a circuit layer of the multi-layer FPC board;

laminating a single-layer FPC board, and laminating the multi-layer FPC board, the pure glue and the single-layer FPC board which are manufactured with inner-layer circuits in sequence, wherein the circuit surface of the golden finger back of the multi-layer FPC board and the copper foil surface of the single-layer FPC board are placed towards the pure glue;

and (3) uncovering the bending area, uncovering the part, corresponding to the bending area, of the pressed single-layer FPC board, and forming a cover film replacement structure on the back of the golden finger by the single-layer FPC board after uncovering.

7. The cover film replacement process for the back surface of the gold finger of the multi-layer FPC board according to claim 6, wherein the single-layer FPC board is identical to the multi-layer FPC board in size.

8. The cover film replacement process for the back surface of the gold finger of the multi-layer FPC board according to claim 7, further comprising the step of, before laminating the single-layer FPC board:

and manufacturing a single-layer FPC board circuit, and manufacturing a circuit on the copper foil surface of the single-layer FPC board to form an outermost inner circuit on the back surface of the golden finger of the multi-layer FPC board.

9. The cover film replacement process for the back surface of the gold finger of the multi-layer FPC board according to claim 6, further comprising the step of, before the lamination of the single-layer FPC board: and windowing the pure glue corresponding to the bending area.

10. The process for replacing the cover film on the back of the golden finger of the multi-layer FPC board according to claim 6, wherein the surface of the bending area of the manufactured inner layer circuit is coated with an ink layer before the single-layer FPC board is pressed.