阅读说明：本技术 一种刚挠结合板的制作方法 (Manufacturing method of rigid-flex printed circuit board ) 是由 黄望望 寻瑞平 吴家培 覃红秀 何淼 于 2019-11-12 设计创作，主要内容包括：本发明涉及印制电路板技术领域,具体为一种刚挠结合板的制作方法。本发明通过改变压合结构,压合过程无需在半固化片上形成pp开窗,同时通过在预切区贴设PI保护膜,压合结构中半固化片无需内缩设置,不仅可提供充足的流胶保证刚挠层的结合效果,且不存在流胶过多而溢至pp开窗处(即粘结到挠性区)的问题。另一方面,因无需设置PP开窗,避免现有技术中因PP开窗造成开窗位高落差,导致压合表面形成突起或凹陷等平整性问题。(The invention relates to the technical field of printed circuit boards, in particular to a method for manufacturing a rigid-flex printed circuit board. According to the invention, by changing the pressing structure, pp windowing is not required to be formed on the prepreg in the pressing process, and meanwhile, the PI protective film is adhered to the precut area, so that the prepreg in the pressing structure is not required to be arranged in a retracted manner, sufficient glue flow can be provided to ensure the combination effect of the rigid-flex layer, and the problem that the excessive glue flow overflows to the pp windowing part (namely, is adhered to the flexible area) is avoided. On the other hand, because of not needing to set up PP and windowing, avoid among the prior art because of PP windowing causes the high drop of windowing position, lead to pressfitting surface to form smoothness problems such as protruding or sunken.)

1. A method for manufacturing a rigid-flex printed circuit board is characterized by comprising the following steps,

s1: manufacturing a rigid layer: manufacturing a circuit on the rigid core board, and routing blind grooves around the edge of the cut-off area on the rigid core board;

manufacturing a flexible layer: manufacturing a circuit on a flexible board, and pasting a cover film on a flexible area of the flexible board, wherein the size of the cover film is larger than that of a single side of the flexible area;

manufacturing a bonding layer: adhering a PI protective film on one surface of the prepreg, which is opposite to the flexible layer, wherein the area of the prepreg, which corresponds to the flexible area, is called a precut area, cutting along the edge of the precut area to separate the precut area from the prepreg, and tearing off the PI protective film on the prepreg except the precut area;

s2: laminating and pressing the flexible layer, the bonding layer and the rigid layer into a whole to form a multilayer production plate;

s3: sequentially drilling a multilayer production board, depositing copper, electroplating the whole board, manufacturing an outer layer circuit, manufacturing a solder mask and performing surface treatment on the multilayer production board;

s4: and carrying out forming treatment on the multilayer production plate, cutting the rigid layer side of the multilayer production plate around the edge of the cutting area through depth control milling and butting the rigid layer side with the blind groove, and taking out the cutting area, the precutting area and the PI protective film on the precutting area from the multilayer production plate to expose the flexible area of the flexible layer.

2. The method of manufacturing a rigid-flex printed circuit board according to claim 1, wherein in step S1, the size of the cover film is 0.5 to 1.0mm larger than the single side of the flexible region.

3. The method of manufacturing a flex-rigid board according to claim 1, wherein the precut section is separable from the prepreg by laser cutting along the edge of the precut section in step S1.

4. The method of manufacturing a rigid-flex printed circuit board according to claim 1, wherein in step S2, the flexible layer and the rigid layer are browned before the flexible layer, the adhesive layer and the rigid layer are laminated together.

5. The method of manufacturing a rigid-flex printed circuit board according to claim 4, wherein in the manufacturing of the flexible layer in step S1, after the wiring is formed on the flexible board, the flexible board is browned, a cover film is attached to the flexible area, and then the flexible board is browned again.

Technical Field

The invention relates to the technical field of printed circuit boards, in particular to a method for manufacturing a rigid-flex printed circuit board.

Background

The rigid-flex board is also called a soft-hard board and is formed by selectively laminating a rigid board and a flexible board, and the rigid-flex board is compact in structure and is in conductive connection with a metalized hole. The printed circuit board combined by rigid and flexible materials fully utilizes the characteristics of the flexible board, solves the problem of electrical connection with the rigid board, takes account of the regularity and toughness of the conventional rigid board and the flexibility and smallness of the flexible board, can move, bend, fold and twist the rigid-flexible combined board, realizes three-dimensional wiring, greatly saves the installation space of electronic components, conforms to the development trend of light, thin, short and small electronic products, is widely applied in various fields of military industry, aerospace, automotive electronics, medical electronics, civil consumer electronics and the like in recent decades, becomes the most rapidly developed PCB product at present, and is also one of the main development directions of future PCBs.

The rigid-flex bonded panel includes a rigid layer and a flexible layer, the region of the flexible layer exposed is referred to as the flexible region, and the region of the rigid layer opposite the flexible region during fabrication is referred to as the cut-out region. The core step of manufacturing the rigid-flex combined board is to press and manufacture the window so that the flexible layer is partially exposed to form the flexible area, the window is manufactured in various modes, and the most widely applied mode is mechanical depth control milling. The mechanical depth control milling is to cut a certain depth on the rigid plate around the edge of the cut-off region by a mechanical or laser method in advance to form a blind groove in the cut-off region of the rigid plate, and cut off the region corresponding to the flexible region on the prepreg (PP) to form a PP windowing; and then combining the rigid layer and the flexible layer with the cover film adhered to the flexible region into a whole through a prepreg, then normally performing other post processes, finally cutting the edge of the cut-off region surrounding the rigid layer in a mechanical depth control milling mode and butting the cut-off region with the pre-cut blind groove to take out the plate of the cut-off region so as to expose the flexible layer, completing the manufacturing of a window and forming the flexible region. The specific process flow comprises the following steps:

1. flexible plate portion: cutting → inner layer pattern → inner layer etching → inner layer AOI → browning → cover film windowing → cover film laminating → cover film pressing → OPE punching → browning;

2. rigid plate portion: cutting → inner layer pattern → inner layer etching → OPE punching → inner layer AOI → rigid plate gong blind groove → browning;

3. bonding layer portion: PP cutting → OPE punching → PP windowing;

4. main flow: pressing → X-Ray drilling target hole → milling plate edge → drilling hole → copper deposition, plate electric → outer layer pattern → pattern plating → outer layer etching → outer layer AOI → resistance welding, character → surface treatment → electric test → shaping → window opening after shaping → FQC → FQA → packaging and shipment.

When the rigid layer and the flexible layer are laminated together, as shown in fig. 1, in order to ensure the laminating effect between the flexible layer and the rigid layer, the size of the cover film needs to be larger than that of the flexible region, i.e. the edge of the cover film needs to enter between the interlayers, generally 0.5-1.0mm, meanwhile, in order to prevent the PP from overflowing to the flexible region to affect the product performance and appearance, the PP needs to be designed to be retracted, the size of the opening window of the PP is larger than that of the flexible region, and the design method has the following defects: 1. the pp windowing is arranged in the pressing structure, when in pressing, the glue continuously flows to the gap position, if the excessive glue overflow is too large, the plate surface is easy to bulge, and if the excessive glue overflow is too small, the depression is caused, so that the manufacturing and the appearance smoothness of the outer layer circuit are influenced; 2. the cover film and the PP do not have the overlapped part and are difficult to ensure the bonding effect of the flexible layer and the rigid layer, the bending performance of the product is influenced, and the rigid-flexible combination position is easy to tear in the subsequent use process.

Disclosure of Invention

Aiming at the problems existing in the prior art for manufacturing the rigid-flex board, the invention provides the method for manufacturing the rigid-flex board, which can avoid the problems that a product forms a bulge or a depression, the rigid-flex board is not firmly bonded, the bonding position is easy to tear and the like.

In order to achieve the purpose, the invention adopts the following technical scheme.

A method for manufacturing a rigid-flex printed circuit board comprises the following steps,

s1: manufacturing a rigid layer: manufacturing a circuit on the rigid core board, and routing blind grooves around the edge of the cut-off area on the rigid core board;

manufacturing a flexible layer: manufacturing a circuit on a flexible board, and pasting a cover film on a flexible area of the flexible board, wherein the size of the cover film is larger than that of a single side of the flexible area;

manufacturing a bonding layer: adhering a PI protective film on one surface of the prepreg, which is opposite to the flexible layer, wherein the area of the prepreg, which corresponds to the flexible area, is called a precut area, cutting along the edge of the precut area to separate the precut area from the prepreg, and tearing off the PI protective film on the prepreg except the precut area;

s2: laminating and pressing the flexible layer, the bonding layer and the rigid layer into a whole to form a multilayer production plate;

s3: sequentially drilling a multilayer production board, depositing copper, electroplating the whole board, manufacturing an outer layer circuit, manufacturing a solder mask and performing surface treatment on the multilayer production board;

s4: and carrying out forming treatment on the multilayer production plate, cutting the rigid layer side of the multilayer production plate around the edge of the cutting area through depth control milling and butting the rigid layer side with the blind groove, and taking out the cutting area, the precutting area and the PI protective film on the precutting area from the multilayer production plate to expose the flexible area of the flexible layer.

Preferably, in step S1, the cover film has a size 0.5 to 1.0mm larger than a single side of the flexible region.

Preferably, the precut area is separated from the prepreg by laser cutting along the edge of the precut area in step S1.

Preferably, in step S2, the flexible layer and the rigid layer are browned before the flexible layer, the adhesive layer and the rigid layer are laminated together.

More preferably, in the step S1 of manufacturing the flexible layer, after the wiring is formed on the flexible board, the flexible board is browned, the cover film is attached to the flexible area, and then the flexible board is browned again.

Compared with the prior art, the invention has the beneficial effects that:

the PI protective film is pasted on the prepreg, and the prepreg is cut around the edge of the precut area by laser to form the independent precut area with one surface pasted with the PI protective film, the precut area is still remained in the laminating structure during laminating, and the precut area and the cut-off area are removed together to expose the flexible area during final molding. Because the precut area is cut from the prepreg before lamination, the fiber yarns at the cut are cut off, even if the cut is filled by glue flow during lamination, the cut can be directly cut off to take out the precut area due to no fiber yarn support.

According to the invention, by changing the pressing structure, pp windowing is not required to be formed on the prepreg in the pressing process, and meanwhile, the PI protective film is adhered to the precut area, so that the prepreg in the pressing structure is not required to be arranged in a retracted manner, sufficient glue flow can be provided to ensure the combination effect of the rigid-flex layer, and the problem that the excessive glue flow overflows to the pp windowing part (namely, is adhered to the flexible area) is avoided. On the other hand, because of not needing to set up PP and windowing, avoid among the prior art because of PP windowing causes the high drop of windowing position, lead to pressfitting surface to form smoothness problems such as protruding or sunken.

Drawings

FIG. 1 is a schematic view of a rigid layer, a flexible layer, and a prepreg stacked together in a prior art rigid-flex printed circuit board manufacturing process;

fig. 2 is a schematic view of the flexible layer, the adhesive layer, and the rigid layer laminated together in the example.

Detailed Description

In order to more fully understand the technical contents of the present invention, the technical solutions of the present invention will be further described and illustrated with reference to the following specific embodiments.