TWI656819B - Flexible circuit board manufacturing method - Google Patents

Abstract

A method for manufacturing a flexible circuit board includes the steps of: providing a carrier board; forming different first and second patterned resin layers on opposite sides of the carrier board, respectively; First and second conductive circuit patterns are respectively formed in the pattern gaps of the second patterned resin layer; a first and a second cover film are respectively formed on the sides of the first and second conductive circuit patterns remote from the carrier board. Layer; removing the carrier board; and covering a third cover film layer on a side of the first conductive circuit pattern remote from the first cover film layer, so as to obtain a first flexible circuit board, and A side of the second conductive circuit pattern remote from the second cover film layer is covered with a fourth cover film layer to obtain a second flexible circuit board.

Description

Manufacturing method of flexible circuit board

The invention relates to a method for manufacturing a flexible circuit board.

Electronic products are becoming thinner, thinner, and smarter. This requires the development of high-frequency, high-speed, thin, and dense circuit boards in order to allow the board to transmit more high-frequency and high-speed signals and connect more. Different chips and modules.

Therefore, it is necessary to provide a simple and practical method for manufacturing a flexible circuit board with high production efficiency, which can meet the development trend of high frequency, high speed, thinness, and dense circuits.

A method for manufacturing a flexible circuit board includes the steps of: providing a carrier plate; and forming a first patterned resin layer and a second patterned resin layer on opposite sides of the carrier plate, respectively, wherein the first patterned The pattern of the resin layer and the pattern of the second patterned resin layer are two different patterns; a first conductive circuit pattern is formed between the pattern gaps of the first patterned resin layer and a pattern of the second patterned resin layer The pattern gap forms a second conductive circuit pattern, wherein the first conductive circuit pattern and the second conductive circuit pattern are two different conductive circuit patterns; the first conductive circuit pattern is far from the base layer A first cover film layer is formed on one side, and a second cover film layer is formed on the side of the second conductive circuit pattern away from the base layer; the carrier board is removed; and the first A third cover film layer is covered on a side of the conductive circuit pattern remote from the first cover film layer, so as to obtain a first flexible circuit board, and the second cover is separated from the second cover on the second conductive circuit pattern. One side of the layer is covered with a fourth cover film layer to obtain a second flexible circuit board; wherein an opening is formed in the first cover film layer and / or the third cover film layer, and the second cover film An opening is also formed in the layer and / or the fourth cover film layer to expose part of the first conductive circuit pattern and part of the second conductive circuit pattern.

Compared with the prior art, the method for manufacturing a flexible circuit board of this technical solution can simultaneously form conductive lines on both sides of a carrier board, and two flexible circuit boards can be obtained after the carrier board is removed, thereby reducing the manufacturing cost of the circuit board and increasing the circuit board. Manufacturing efficiency; and in the method for manufacturing a flexible circuit board of the present technical solution, the circuits of the two flexible circuit boards are embedded in the resin layer, so that the thickness of the flexible circuit board is greatly reduced, and the distance between the circuit and the resin layer is further reduced. The binding force is greatly enhanced, that is, the flexible circuit board manufacturing method of the present case can produce a thinner and thinner flexible circuit board with more stable performance.

An embodiment of the present invention provides a method for manufacturing a flexible circuit board, including the following steps:

As a first step, referring to FIG. 1, a carrier board 100 is provided. The carrier board 100 includes a base layer 110 and conductive layers 120 formed on opposite sides of the base layer 110.

The material of the base layer 110 is preferably polyethylene terephthalate (PET), so that the conductive layer 120 can be easily formed, and has a lower cost.

The material of the conductive layer 120 is a conductive metal or a conductive polymer film. The conductive layer 120 may be formed by performing chemical nickel / chromium (Ni / Cr) treatment and sputtering on the opposite sides of the base layer 110. Copper plating, electroless copper plating, or conductive polymer film coating. Wherein, the thickness of the conductive layer 120 may be 1 micrometer to 2 micrometers, or less than 1 micrometer, and it may be set according to the process capability and the process needs.

In this embodiment, the conductive layer 120 is made of copper, and is formed by electroless copper plating on the opposite sides of the base layer 110.

In the second step, referring to FIG. 2, a first patterned resin layer 210 and a second patterned resin layer 220 are respectively formed on the surfaces of the conductive layers 120 on opposite sides of the base layer 110.

The pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 are both set according to the design requirements of the circuit board. The pattern gap of the first patterned resin layer 210 and the second patterned resin layer 220 are set. The pattern gaps are all used to form conductive lines, that is, the pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 are exactly complementary to the pattern of the conductive lines to be formed therebetween.

The minimum width of the pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 and the minimum width of the pattern gap can be as low as 5 micrometers, which is very beneficial to the formation of fine lines.

The pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 may be the same or different; preferably, the pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 are different. The different patterns are two different patterns, so that two different types of conductive circuit patterns can be formed on the surfaces of the conductive layers 120 on opposite sides of the base layer 110 in subsequent steps.

The first patterned resin layer 210 and the second patterned resin layer 220 may be formed by coating, pressing, or printing. The patterns of the first patterned resin layer 210 and the second patterned resin layer 220 may be formed during coating, lamination, and printing, or may be laser ablated, chemically removed, etc. after coating, lamination, and printing. Way to form.

Preferably, the first patterned resin layer 210 and the second patterned resin layer 220 may be formed on the conductive layer by a liquid photosensitive resin, such as a liquid photosensitive polyimide (PI), by coating, laminating, or printing. 120 surface, and through exposure, development and curing processes to form a pattern. The resolution of the liquid photosensitive resin is better, which is conducive to forming finer and higher-resolution lines in the subsequent steps.

For example, the first patterned resin layer 210 and the second patterned resin layer 220 may be formed in the following manner:

First, a photosensitive resin layer is laminated on the entire surface of the conductive layer 120 on opposite sides of the base layer 110, respectively; after that, the photosensitive resin layer is partially exposed through a patterned photomask; thereafter, unexposed ones are removed by development. The photosensitive resin layer is used to obtain a patterned photosensitive resin layer. Finally, the first patterned resin layer 210 and the second patterned resin layer 220 are obtained by baking and curing.

In the third step, referring to FIG. 3, a first conductive circuit pattern 230 is formed in a pattern gap of the first patterned resin layer 210 and a second conductive circuit pattern 240 is formed in a pattern gap of the second patterned resin layer 220. .

The two opposite surfaces of the first conductive circuit pattern 230 are flush with the corresponding two surfaces of the first patterned resin layer 210, and the two opposite surfaces of the second conductive circuit pattern 240 are corresponding to the corresponding two surfaces. The two opposite surfaces of the second patterned resin layer 220 are flush with each other; that is, the first conductive circuit pattern 230 is embedded in the pattern gap of the first patterned resin layer 210, and the second conductive circuit The pattern 240 is embedded in the pattern gap of the second patterned resin layer 220.

Because the minimum width of the pattern of the first patterned resin layer 210 and the pattern of the second patterned resin layer 220 and the minimum width of the pattern gap can be as low as 5 micrometers, the first conductive circuit pattern 230 and the Both the line width and the line gap of the second conductive line pattern 240 can be as low as 5 microns, that is, a thinner and higher-density line can be formed; and the first conductive line pattern 230 and the second The conductive circuit pattern 240 is not formed by an etching process, so that common etching circuit defects such as circuit side etching and circuit wiring will not occur.

Preferably, the first conductive circuit pattern 230 and the second conductive circuit pattern 240 are formed by electroplating. Preferably, a smoothing process is further included after electroplating to make the surface of the conductive circuit pattern on the same side of the base layer 110. It is flush with the surface of the patterned resin layer.

Preferably, the first conductive circuit pattern 230 and the second conductive circuit pattern 240 are two different conductive circuit patterns.

Fourth step, referring to FIG. 4, a first cover film layer 250 is formed on a side of the first conductive circuit pattern 230 away from the base layer 110, and away from the second conductive circuit pattern 240. A second cover film layer 260 is formed on one side of the base layer 110.

The first cover film layer 250 includes a first film layer 251 and a first adhesive layer 252 that are adhered to each other. The first adhesive layer is directly connected to the first conductive circuit pattern 230 and the first patterned resin layer 210. The second cover film layer 260 includes a second film layer 261 and a second adhesive layer 262 which are adhered to each other. The second adhesive layer is in contact with the second conductive circuit pattern 240 and a second patterned resin. The layers 220 are all directly bonded. Preferably, the material of the first film layer 251 and the second film layer 261 is polyimide.

The first cover film layer 250 is formed with an opening so that part of the first conductive line pattern 230 is exposed from the first cover film layer 250, and the first conductive film exposed to the first cover film layer 250 is exposed. The circuit pattern 230 forms at least one group of first electrical contact pads 231, and each group of the first electrical contact pads 231 is used to be electrically connected to another electronic component, a circuit board, or the like. In this embodiment, there are two sets of first electrical contact pads 231.

In other embodiments, the first electrical contact pad 231 may not be formed; the second cover film layer 260 may have an opening so that part of the second conductive circuit pattern 240 is covered from the second cover. The film layer 260 is exposed to form an electrical contact pad.

In a fifth step, referring to FIG. 5, the carrier plate 100 is removed.

In this embodiment, because the conductive layer 120 is a copper layer, and its bonding force with the base layer 110 is small, the base layer 110 is first removed by a physical method, that is, the base layer 110 is first removed from two layers. The conductive layer 120 on the side is peeled off, and then the conductive layer 120 is removed by chemical etching.

Specifically, the conductive layer 120 is removed by a rapid etching method. The first conductive line pattern 230 and the second conductive line pattern 240 are also slightly etched, so that the first conductive line pattern 230 is located on a side away from the first cover film layer 250, The second conductive circuit pattern 240 is slightly concave on the side far from the second cover film layer 260. Of course, if the etching parameters are controlled within a certain range, the depression may not be formed.

If the conductive layer 120 is made of a nickel-chromium material, a strong acidic etching solution is required for etching, and the depth of the depression may be larger, that is, a significant depression is present. Wherein, the depression does not affect the conductive performance of the conductive lines; and if the first conductive line pattern 230 is away from the side of the first cover film layer 250 and the second conductive line pattern 240 is far away from the An electrical contact pad needs to be formed on one side of the second cover film layer 260, and the depression can also increase the contact area between the electrical contact pad and the solder, thereby enhancing the bonding force between the part and the electrical contact pad.

In other embodiments, depending on the bonding force between the conductive layer 120 and the base layer 110, the base layer 110 may not be peeled off first, but the conductive layer 120 and the base layer 110 may be directly separated. The first conductive line pattern 230 and the second conductive line pattern 240 are peeled from each other, so that the carrier plate 100 is peeled off. At this time, the depression is not formed. For example, if the conductive layer is not a metal material, but a polymer conductive film layer, the conductive layer 120 connected to both sides of the base layer 110 can be directly peeled together without forming the depression, that is, the The first conductive line pattern 230 is still flush with the first patterned resin layer 210 on the side far from the first cover film layer 250, and the second conductive line pattern 240 is far from the second cover film. One side of the layer 260 is still flush with the second patterned resin layer 220.

Sixth step, referring to FIGS. 6-7, a third cover film layer 270 is covered on a side of the first conductive circuit pattern 230 away from the first cover film layer 250 to obtain a first flexible circuit board. 31, and a fourth cover film layer 280 is covered on a side of the second conductive circuit pattern 240 far from the second cover film layer 260 to obtain a second flexible circuit board 32.

The third cover film layer 270 includes a third film layer 271 and a third adhesive layer 272 that are adhered to each other. The third adhesive layer 272 and the first conductive circuit pattern 230 and the first patterned resin layer 210 are both adhered to each other. The fourth cover film layer 280 includes a fourth film layer 281 and a fourth adhesive layer 282 which are adhered to each other. The fourth adhesive layer 282 is in contact with the second conductive circuit pattern 240 and a second pattern. The chemical resin layer 220 is directly adhered to each other. Preferably, the materials of the third film layer 271 and the fourth film layer 281 are polyimide.

The third cover film layer 270 is formed with an opening so that part of the first conductive circuit pattern 230 is exposed from the third cover film layer 270, and the first conductive layer exposed to the third cover film layer 270 is exposed. The circuit pattern 230 forms at least one set of second electrical contact pads 232, and the second electrical contact pads 232 are used for electrical connection with other electronic components, circuit boards, and the like; the fourth cover film layer 280 is formed with an opening so that A portion of the second conductive circuit pattern 240 is exposed from the fourth cover film layer 280, and the second conductive circuit pattern 240 exposed to the fourth cover film layer 280 forms at least one third electrical contact. Pads 241, the third electrical contact pads 241 are used for electrical connection with other electronic components, circuit boards, etc. In this embodiment, there are two sets of third electrical contact pads 241.

In this embodiment, the positions of the at least one first electrical contact pad 231 and the at least one second electrical contact pad 232 are staggered.

In other embodiments, the third cover film layer 270 may not form an opening, so that the second electrical contact pad 232 may not be formed.

According to the method for manufacturing a flexible circuit board of this technical solution, conductive lines can be simultaneously formed on both sides of a carrier board 100, and then the carrier board is peeled off to obtain two flexible circuit boards (ie, the first flexible circuit board 31 and the second flexible circuit Board 32), this method can reduce the manufacturing cost of the circuit board and improve the manufacturing efficiency of the circuit board; and in the flexible circuit board manufacturing method of the present technical solution, the circuits of the two flexible circuit boards are embedded in the resin layer, thereby making the flexible The thickness of the circuit board is greatly reduced, and the bonding force between the circuit and the resin layer is greatly enhanced, that is, the flexible circuit board manufacturing method of the present case can produce a thinner and thinner flexible circuit board with more stable performance.

In addition, electrical contact pads can be formed on both sides of one layer of the conductive circuit of the flexible circuit board of this technical solution to solder parts or circuit boards, that is, the flexible circuit board of this case has a high assemblable density, thereby also making the flexible circuit The volume of the board is relatively small and the manufacturing cost is relatively low; for example, please refer to FIG. 8 to FIG. 9, the two sets of the first electrical contact pads 231 on the first cover film layer 250 side of the first flexible circuit board 31 of the present case may be An electronic component 33 is connected by soldering, and a group of second electrical contact pads 232 on the third cover film layer 270 side can be connected with an electronic component 34 by soldering. The electronic components 33 and 34 can be IC (Integrated Circuit, integrated circuit), etc .; the two sets of the third electrical contact pads 241 on the fourth cover film layer 280 side of the second flexible circuit board 32 of the present case can be connected to a circuit board 35, 36 by soldering, respectively. In other embodiments, the first electrical contact pad 231 and the second electrical contact pad 232 of the first flexible circuit board 31 may be electrically connected to the circuit board, and the third electrical contact of the second flexible circuit board 32 may be electrically connected. Electronic components can also be electrically connected to the pad 241.

It can be understood that, for those having ordinary knowledge in the art, various other corresponding changes and deformations can be made according to the technical concept of the present invention, and all these changes and deformations should belong to the protection scope of the present invention.

100‧‧‧carrying plate

110‧‧‧ foundation layer

120‧‧‧ conductive layer

210‧‧‧The first patterned resin layer

220‧‧‧second patterned resin layer

230‧‧‧ the first conductive line pattern

240‧‧‧ The second conductive line pattern

250‧‧‧first cover film

251‧‧‧The first film layer

252‧‧‧The first glue layer

260‧‧‧second cover film

261‧‧‧Second film layer

262‧‧‧Second glue layer

270‧‧‧ third cover film

271‧‧‧ third layer

272‧‧‧The third glue layer

280‧‧‧ Fourth cover film

281‧‧‧Fourth film layer

282‧‧‧Fourth glue layer

231‧‧‧The first electrical contact pad

232‧‧‧Second electrical contact pad

241‧‧‧Third electrical contact pad

31‧‧‧The first flexible circuit board

32‧‧‧Second flexible circuit board

33‧‧‧Electronic components

34‧‧‧Electronic components

35, 36‧‧‧Circuit board

FIG. 1 is a cross-sectional view of a carrier plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the embodiment of the present invention after a patterned resin layer is formed on both sides of the carrier plate of FIG. 1.

FIG. 3 is a cross-sectional view of the pattern gap of the patterned resin layer in FIG. 2 after a conductive circuit pattern is formed.

FIG. 4 is a cross-sectional view after a cover film layer is formed on the surface of the conductive circuit pattern in FIG. 3.

FIG. 5 is a cross-sectional view with the carrier plate in FIG. 4 removed.

6 to 7 are cross-sectional views after a cover film layer is formed on the other side of the conductive circuit pattern in FIG. 5.

8 to 9 are cross-sectional views of the first and second flexible circuit boards in FIG. 6 and FIG. 7 after the components and the circuit board are respectively soldered.

no

no

Claims (13)

A method for manufacturing a flexible circuit board includes the steps of: providing a carrier plate; and forming a first patterned resin layer and a second patterned resin layer on opposite sides of the carrier plate, respectively, wherein the first patterned The pattern of the resin layer and the pattern of the second patterned resin layer are two different patterns; a first conductive circuit pattern is formed in a pattern gap of the first patterned resin layer and a pattern of the second patterned resin layer The pattern gap forms a second conductive circuit pattern, wherein the first conductive circuit pattern and the second conductive circuit pattern are two different conductive circuit patterns; the first conductive circuit pattern is far from the base layer A first cover film layer is formed on one side, and a second cover film layer is formed on the side of the second conductive circuit pattern remote from the base layer; removing the carrier board; and on the first A side of the conductive circuit pattern far from the first cover film layer is covered with a third cover film layer, so as to obtain a first flexible circuit board, and the second conductive circuit pattern is far from the second One side of the cover film layer covers a fourth cover film layer to obtain a second flexible circuit board; wherein the first cover film layer and / or the third cover film layer are formed with openings, and the second An opening is also formed in the cover film layer and / or the fourth cover film layer to expose part of the first conductive circuit pattern and part of the second conductive circuit pattern. The method for manufacturing a flexible circuit board according to claim 1, wherein the carrier board includes a base layer and conductive layers formed on opposite sides of the base layer, and is formed on the first patterned resin layer by electroplating. The pattern gap forms a first conductive circuit pattern and the second patterned resin layer forms a second conductive circuit pattern in the pattern gap. The method for manufacturing a flexible circuit board according to claim 2, wherein the material of the base layer is polyethylene terephthalate. The method for manufacturing a flexible circuit board according to item 2 of the claim, wherein the material of the conductive layer is metal, and when the carrier board is removed, the base layer is peeled off first, and then the conductive layer is removed by etching. The method for manufacturing a flexible circuit board according to claim 4, wherein when the conductive layer is removed by etching, the first conductive circuit pattern and the second conductive circuit pattern are also slightly etched, so that the The first conductive circuit pattern is slightly concave on the side far from the first cover film layer, and the second conductive circuit pattern is slightly concave on the side far from the second cover film layer. The method for manufacturing a flexible circuit board according to claim 2, wherein, when the carrier board is removed, the conductive layers on both sides of the base layer together with the base layer are separately extracted from the first conductive circuit pattern. And the second conductive circuit pattern side is peeled off, thereby peeling off the carrier board; wherein the two opposite surfaces of the first conductive circuit pattern are respectively aligned with the opposite two surfaces of the corresponding first patterned resin layer The two opposite surfaces of the second conductive circuit pattern are respectively flush with the opposite two surfaces of the corresponding second patterned resin layer. The method for manufacturing a flexible circuit board according to claim 1, wherein the first patterned resin layer and the second patterned resin layer are formed on the conductive layer by a liquid photosensitive resin by coating, lamination, or printing. The surface is formed through exposure, development, and curing processes. The method for manufacturing a flexible circuit board according to claim 1, wherein the first cover film layer is formed with an opening so that part of the first conductive circuit pattern is exposed from the first cover film layer, and is exposed. At least one set of first electrical contact pads is formed on the first conductive circuit pattern of the first cover film layer. The method for manufacturing a flexible circuit board according to claim 8, wherein the third cover film layer is formed with an opening so that part of the first conductive circuit pattern is exposed from the third cover film layer, and is exposed. At least one set of second electrical contact pads is formed on the first conductive circuit pattern of the third cover film layer. The method for manufacturing a flexible circuit board according to claim 9, wherein the at least one set of the first electrical contact pads and the at least one set of the second electrical contact pads are staggered from each other. The method for manufacturing a flexible circuit board according to claim 9, further comprising the step of electrically connecting an electronic component to each of the first electrical connection pads and each of the second electrical connection pads. Or a circuit board. The method for manufacturing a flexible circuit board according to claim 1, wherein the fourth cover film layer is formed with an opening so that part of the second conductive circuit pattern is exposed from the fourth cover film layer, and is exposed. At least one set of third electrical contact pads is formed on the second conductive circuit pattern of the fourth cover film layer. The method for manufacturing a flexible circuit board according to claim 12, further comprising the step of electrically connecting an electronic component or a circuit board to each of the third electrical connection pads.