阅读说明：本技术 一种刚挠结合电路板的制备方法及其产品 (Preparation method of rigid-flex circuit board and product thereof ) 是由 王文宝 于 2019-12-05 设计创作，主要内容包括：本发明涉及一种刚挠结合电路板的制备方法及其产品,其中制备方法通过在半固化片和刚性电路板进行预先切断,使得在开盖时可以直接在切断处撕开,确保了开盖的顺利,并且避免了现有技术中组合后在控深切割时切割深度控制难度高的问题,大大提高了产品的良率。(The invention relates to a preparation method of a rigid-flex circuit board and a product thereof, wherein the preparation method is characterized in that a prepreg and a rigid circuit board are cut off in advance, so that the prepreg and the rigid circuit board can be directly torn at the cut-off part when a cover is opened, the smoothness of the cover opening is ensured, the problem of high difficulty in controlling the cutting depth during depth control cutting after combination in the prior art is solved, and the yield of the product is greatly improved.)

1. A method for preparing a rigid-flex circuit board is characterized by comprising the following steps:

s1, providing a flexible circuit board, a prepreg and a rigid circuit board; wherein the content of the first and second substances,

a rigid-flexible combination area and a flexible area are planned on the flexible circuit board;

the prepreg comprises a substrate and colloid positioned on the substrate, wherein the prepreg is provided with a first cutting seam which is arranged along a boundary line of a rigid-flex area and a flexible area of the flexible circuit board, the substrate of the prepreg is cut off along the first cutting seam, and the prepreg is divided into a first area and a second area corresponding to the rigid-flex area and the flexible area of the flexible circuit board by the first cutting seam; the second area of the prepreg is provided with a shielding film covering the second area;

the rigid circuit board is provided with a second cutting seam which is arranged along a boundary line of the rigid-flexible combination area and the flexible area which are opposite to the flexible circuit board, the rigid circuit board is cut off along the second cutting seam, and the rigid circuit board is divided into a third area and a fourth area which correspond to the rigid-flexible combination area and the flexible area of the flexible circuit board by the second cutting seam;

s2, stacking and combining the flexible circuit board, the prepreg and the rigid circuit board provided in the step S1 according to a stacked structure, wherein the first area of the prepreg and the third area of the rigid circuit board correspond to a flex-rigid area of the flexible circuit board, and the second area of the prepreg and the fourth area of the rigid circuit board correspond to a flexible area of the flexible circuit board;

s3, performing lamination processing on the laminated structure formed in the step S2 to enable a third area of the rigid circuit board to be bonded on a rigid-flex area of the flexible circuit board through a first area of a prepreg, and a fourth area of the rigid circuit board to be bonded with the shielding membrane into a whole through a second area of the prepreg;

s4, carrying out post-processing treatment on the product after the laminating treatment of the step S3 to lead the circuit on the rigid circuit board and the circuit on the flexible circuit board to be conducted;

and S5, removing the fourth area on the rigid circuit board, the second area of the prepreg and the shielding film in the product which is subjected to the step S4, and obtaining the rigid-flex printed circuit board.

2. The method of claim 1, wherein: the masking film is an adhesive tape that can withstand the high temperature at the time of lamination in step S3.

3. The method of claim 1, wherein: the masking film on the prepreg in the step S1 is formed by:

s11, combining the shielding film exceeding the second area of the prepreg on the prepreg;

s12, forming a first cutting seam at the position corresponding to the boundary of the rigid-flex region and the flexible region, wherein the first cutting seam cuts off the base material of the prepreg and the shielding membrane on the prepreg together;

and S13, removing the shielding film beyond the second area of the prepreg along the first slit, and thus obtaining the shielding film completely matched with the second area of the prepreg.

4. The production method according to claim 3, characterized in that: the first slit is formed by laser cutting.

5. The production method according to claim 3, characterized in that: the base material of the prepreg is glass fiber cloth.

6. A rigid-flex circuit board, its characterized in that: the flex-rigid circuit board is prepared by the preparation method of any one of claims 1 to 5.

Technical Field

The invention relates to the field of circuit boards, in particular to a method for preparing a rigid-flex circuit board and a product thereof.

Background

The rigid-flex circuit board combines the flexibility of the flexible circuit board and the durability of the rigid circuit board, can realize three-dimensional assembly under different conditions, and is widely applied to industries, high-end medical treatment, military equipment and other consumer portable electronic products.

The existing flex-rigid circuit board is mostly formed by adopting a layer-adding mode, namely, an inner layer soft board is firstly formed, then hard board materials are formed on two sides of the inner layer soft board, and a part of the inner layer soft board is exposed, so that the flex-rigid circuit board is formed. This way of making presents at least the following problems:

1. when the depth control milling or the laser cover opening operation is carried out, the depth control milling or the laser cover opening has high depth control difficulty; if the milling depth is too shallow, the hard plate 30' is not cut completely, and burrs can be generated when the cover is opened; if the milling depth is too deep, the flexible circuit board is damaged, resulting in low yield.

2. When the prepreg (PP) is laminated, the glue overflows to the flexible region 101 'and the rigid board 30' corresponding to the flexible region 101 'for adhesion, which results in difficulty in opening the cover and easy tearing of the flexible circuit board 10', resulting in low yield.

Disclosure of Invention

The invention aims to provide a method for preparing a rigid-flexible printed circuit board, which aims to solve the problem of low yield in the manufacturing process of the conventional rigid-flexible printed circuit board.

The specific scheme is as follows:

a method for preparing a rigid-flex circuit board comprises the following steps:

s1, providing a flexible circuit board, a prepreg and a rigid circuit board; wherein the content of the first and second substances,

a rigid-flexible combination area and a flexible area are planned on the flexible circuit board;

the prepreg comprises a substrate and colloid positioned on the substrate, wherein the prepreg is provided with a first cutting seam which is arranged along a boundary line of a rigid-flex area and a flexible area of the flexible circuit board, the substrate of the prepreg is cut off along the first cutting seam, and the prepreg is divided into a first area and a second area corresponding to the rigid-flex area and the flexible area of the flexible circuit board by the first cutting seam; the second area of the prepreg is provided with a shielding film covering the second area;

the rigid circuit board is provided with a second cutting seam which is arranged along a boundary line of the rigid-flexible combination area and the flexible area which are opposite to the flexible circuit board, the rigid circuit board is cut off along the second cutting seam, and the rigid circuit board is divided into a third area and a fourth area which correspond to the rigid-flexible combination area and the flexible area of the flexible circuit board by the second cutting seam;

s2, stacking and combining the flexible circuit board, the prepreg and the rigid circuit board provided in the step S1 according to a stacked structure, wherein the first area of the prepreg and the third area of the rigid circuit board correspond to a flex-rigid area of the flexible circuit board, and the second area of the prepreg and the fourth area of the rigid circuit board correspond to a flexible area of the flexible circuit board;

s3, performing lamination processing on the laminated structure formed in the step S2 to enable a third area of the rigid circuit board to be bonded on a rigid-flex area of the flexible circuit board through a first area of a prepreg, and a fourth area of the rigid circuit board to be bonded with the shielding membrane into a whole through a second area of the prepreg;

s4, carrying out post-processing treatment on the product after the laminating treatment of the step S3 to lead the circuit on the rigid circuit board and the circuit on the flexible circuit board to be conducted;

and S5, removing the fourth area on the rigid circuit board, the second area of the prepreg and the shielding film in the product which is subjected to the step S4, and obtaining the rigid-flex printed circuit board.

In some embodiments, the masking film is an adhesive tape that can withstand the high temperatures of lamination in step S3.

In some embodiments, the masking film on the prepreg in step S1 is formed by:

s11, combining the shielding film exceeding the second area of the prepreg on the prepreg;

s12, forming a first cutting seam at the position corresponding to the boundary of the rigid-flex region and the flexible region, wherein the first cutting seam cuts off the base material of the prepreg and the shielding membrane on the prepreg together;

and S13, removing the shielding film beyond the second area of the prepreg along the first slit, and thus obtaining the shielding film completely matched with the second area of the prepreg.

In some embodiments, the first kerf is formed by laser cutting.

In some embodiments, the substrate of the prepreg is a fiberglass cloth.

The invention also provides a rigid-flexible printed circuit board which is prepared by the preparation method.

Compared with the prior art, the preparation method of the rigid-flexible combined circuit board provided by the invention has the following advantages:

1. in the preparation method provided by the invention, because the base material of the second area of the prepreg and the fourth area of the rigid circuit board are cut off in advance, no dragging force exists between the second area and the first area of the prepreg, the prepreg can be directly torn at the cut-off part, and the cover opening is ensured to be smooth.

2. Due to the fact that the cover opening part is used for cutting before combination, the problem that in the prior art, after combination, cutting depth control difficulty is high during depth control cutting is solved, product defects are reduced, and the yield of products is greatly improved.

3. The laminating shields the diaphragm in the prepreg, has avoided prepreg glue to spill over the problem in the flexible zone when the pressfitting for the border in rigid-flex bonded area is more level and smooth, more is favorable to the operation of uncapping, in order to ensure uncapping smoothly, has improved the yield of product.

Drawings

Fig. 1 is a schematic diagram showing the steps of manufacturing a rigid-flex circuit board in the prior art.

Fig. 2a shows a schematic view of a flexible circuit board of the present invention.

Fig. 2b shows a schematic representation of a prepreg according to the invention.

Fig. 2c shows a schematic view of the rigid circuit board of the present invention.

Fig. 3 shows a schematic view of a laminated structure of the rigid-flex printed circuit board of the present invention.

Fig. 4 shows a schematic view of a flex-rigid circuit board of the present invention after lamination assembly.

Fig. 5 shows a schematic view of the flex-rigid circuit board of the present invention.

Fig. 6 shows a schematic diagram of the steps of fabricating a masking film on a prepreg according to the present invention.

Detailed Description

To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The invention will now be further described with reference to the accompanying drawings and detailed description.

The embodiment provides a method for manufacturing a rigid-flex printed circuit board, and referring to fig. 2 to 5, the method includes the following steps:

and S1, providing the flexible circuit board 10, the prepreg 20 and the rigid circuit board 30. In the present embodiment, an fpc (flexible Printed Circuit) board is used as the flexible Circuit board 10, a pcb (Printed Circuit board) board is used as the rigid Circuit board 30, and the Prepreg 20 may be a Low Flow Prepreg (Low Flow Prepreg) or a No Flow Prepreg (No Flow Prepreg).

Referring to fig. 2a, inner layer circuits and film pasting processes are completed on the flexible circuit board 10, and the flexible circuit board 10 is planned with a rigid-flexible bonding area 100 and a flexible area 101.

Referring to fig. 2b, the prepreg 20 is a sheet formed by a substrate and a glue on the substrate, in this embodiment, a glass fiber cloth is used as the substrate, but the substrate is not limited thereto, and a substrate having the same or similar functions is also suitable for this purpose. But the glass fiber cloth can have a relatively flat section in the subsequent operation cutting operation and is easy to be cut, thereby being beneficial to the subsequent laminating process and uncovering operation.

The prepreg 20 is subjected to a cutting and slitting process along a boundary line of the rigid-flexible bonding region 100 and the flexible region 101 which are opposite to the flexible circuit board 10, a first cutting and slitting 201 is formed at a position corresponding to the boundary line of the rigid-flexible bonding region 100 and the flexible region 101, at this time, the base material of the prepreg 20 is cut along the cutting and slitting 201, but colloids on the base material are mutually fused to enable the prepreg 20 to still maintain the integral shape, and no dragging force exists between the cut base materials, so that the prepreg can be directly torn along the cutting and slitting position of glass fibers. Additionally, the die cutting seam process can be realized by processing in a laser mode, a wire saw mode and the like. The prepreg 20 is divided by a first slit 201 into a first region 202 corresponding to the flex-rigid bond region 100 of the flexible circuit board 10 and a second region 203 corresponding to the flexible region 101 of the flexible circuit board 10.

The second region 203 of the prepreg 20 has a shielding film 21 thereon which just covers the second region 201. The shielding film 21 can withstand the temperature of the flex-rigid circuit board during high-temperature lamination, and may be a film made of a temperature-resistant material such as Polyimide (PI), polyethylene terephthalate (PET), etc. In the present embodiment, the shielding film 21 is preferably a high-temperature adhesive tape (e.g., a polyimide-based high-temperature adhesive tape), which can be directly bonded and fixed on the prepreg 20 while satisfying the high-temperature shielding function, so as to simplify the operation steps and improve the production efficiency.

Referring to fig. 2c, rigid circuit board 30 is also subjected to a punching and slitting process along the boundary between rigid-flexible bonded region 100 and flexible region 101 facing flexible circuit board 10, and second slit 301 is formed at the boundary between rigid-flexible bonded region 100 and flexible region 101, at which time the portion corresponding to rigid-flexible bonded region 100 and the portion corresponding to flexible region 101 are cut off. The rigid circuit board 30 is divided by the second slits 301 into a third region 302 corresponding to the rigid-flex bonding region 100 of the flexible circuit board 10 and a fourth region 303 corresponding to the flexible region 101 of the flexible circuit board 10. Since the rigid circuit board 30 is rigid, the rigid circuit board 30 can be assembled and spliced into an integral shape even if cut. In addition, in actual production, most of the circuit boards are produced by panel assembly, so that the third areas 302 between the adjacent rigid circuit boards 30 are connected, the second slits 301 are formed in the rigid circuit boards of the panel assembly, and the fourth areas 303 and the third areas 302 can maintain the overall shape by means of the tight fit between the third areas 302 and the fourth areas. In addition, the die cutting seam process can be implemented by laser and other methods.

S2, the flexible circuit board 10, the prepreg 20 and the rigid circuit board 30 provided in the above step S1 are combined in a stacked configuration. Referring to fig. 3, since the rigid circuit boards 30 are disposed on both sides of the rigid-flex circuit board in the embodiment, a sandwich-like stacked structure of the rigid circuit board 30, the prepreg 20, the flexible circuit board 10, the prepreg 20, and the rigid circuit board 30 is sequentially formed in this embodiment.

S3, the laminated structure formed in the step S2 is laminated to form the laminated structure shown in fig. 4. Referring to fig. 4, since the base material of the prepreg 20 is cut along the first slit 201 and the rigid wiring board 30 is cut along the second slit 301, after lamination, the glue on the prepreg 20 is re-fused and cured at a high temperature during lamination, so that the third region 302 of the rigid wiring board 30 is bonded to the flex-rigid bonding area 100 of the flexible wiring board 10 through the first region 202 of the prepreg 20, and the fourth region 303 of the rigid wiring board 30 is bonded to the shielding film 21 through the second region 203 of the prepreg 20. Moreover, due to the thickness difference of the shielding film 21 on the prepreg 20, the shielding film 21, the fourth region 303 of the rigid circuit board 30 and the second region 203 of the prepreg 20 form a fault structure.

During the lamination process, since the glue on the two sides of the first slit 201 of the prepreg 20 is melted together at the position of the slit, the sealing of the slit is ensured, and the process liquid medicine can be prevented from entering from the slit to pollute the surface of the flexible region 101.

In addition, the shielding film 21 plays a role of blocking glue at the fault, so that the glue in the first area 202 of the prepreg 20 can be prevented from overflowing, the bonding between the third area 302 of the rigid circuit board 30 and the rigid-flex bonding area 100 of the flexible circuit board 10 is ensured, the glue in the first area 202 of the prepreg 20 can be prevented from overflowing into the flexible area 101 of the flexible circuit board 10, and the subsequent uncapping operation of a product can be ensured to be smooth.

And S4, performing post-processing treatment on the product after the laminating treatment of the step S3, wherein the post-processing treatment can comprise drilling, copper deposition, circuit etching, solder resistance, surface treatment and other processes, so that the circuit on the rigid circuit board 30 is conducted with the circuit on the flexible circuit board 10. Since the post-processing is well known in the art, it is not described in detail.

And S5, carrying out uncovering treatment on the product after the step S4, and removing the fourth area 303 of the rigid circuit board 30, the second area 203 of the prepreg 20 and the shielding film 21 together to obtain the rigid-flex printed circuit board.

Referring to fig. 2 to fig. 5, the method for manufacturing the flex-rigid circuit board provided in this embodiment has the following advantages:

1. since the base material of the second region 203 of the prepreg 20 and the fourth region of the rigid circuit board 30 are cut in advance, no pulling force is applied between the second region 203 and the first region 202 of the prepreg 20, and the prepreg can be directly torn at the cut position, thereby ensuring the smoothness of opening the cover.

2. Due to the fact that the cover opening part is used for cutting before combination, the problem that in the prior art, after combination, cutting depth control difficulty is high during depth control cutting is solved, product defects are reduced, and the yield of products is greatly improved.

3. The membrane 21 is shielded in the prepreg 20 in a laminating manner, so that the problem that glue of the prepreg 20 overflows into the flexible area during laminating is solved, the edge of the rigid-flex area is smoother, the uncovering operation is more facilitated, the smoothness of uncovering is ensured, and the yield of products is improved.

In the present embodiment, referring to fig. 6, the masking film 21 on the prepreg 20 may be formed by the following steps:

s11, bonding the masking film 21 on the prepreg 20 beyond the second region 203 of the prepreg 20.

S12, a first slit 201 is formed at the boundary between the rigid-flex region 100 and the flexible region 101, and the first slit 201 cuts the base material of the prepreg 20 together with the masking film 21 on the prepreg 20.

S13, removing the masking film 21a beyond the second region 203 of the prepreg 20 along the first slits 201 to obtain a masking film 21a completely matching the second region 203 of the prepreg 20.

The first slit 201 is preferably realized by laser cutting, the laser cutting can have slits with smaller intervals, the flatness of the slits is better, the glue blocking effect of the shielding film 21 in the subsequent lamination operation is facilitated, and the yield of products is finally improved.

By adopting the method, the size of the shielding film 21 can be completely matched with the second area 203 of the prepreg 20, errors can not exist theoretically, the glue in the first area of the prepreg 20 can not overflow into the flexible area 101 of the flexible circuit board 10 during the laminating operation, and the foundation is provided for the smooth subsequent uncapping operation. While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.