TWI410189B - Printed ciucuit board substrate and method for manufacturing the same - Google Patents

Abstract

A printed circuit board substrate includes a first metal layer and an epoxy resin composite material layer adhered to a surface of the first metal layer. The epoxy resin composite material layer is essentially epoxy resin composite material with a viscosity in a range about 10000 centipoises to 30000 centipoises. The epoxy resin composite material includes epoxy resin modified by a carboxyl-terminated polymer and thermoplastic polyurethane. A weight content of the thermoplastic polyurethane in the epoxy resin composite material is in a range from 6% to 20%. The present invention also provides a method for manufacturing the printed circuit board substrate.

Description

Circuit board substrate and manufacturing method thereof

The present invention relates to the field of circuit board technology, and in particular, to a circuit board substrate that is maintained in a flexed state after being bent once and a manufacturing method thereof.

With the advancement of science and technology, printed circuit boards are widely used in digital fields. For application of the circuit board, please refer to the literature Takahashi, A. Ooki, N. Nagai, A. Akahoshi, H. Mukoh, A. Wajima, M. Res. Lab, High density multilayer printed circuit board for HITAC M-880, IEEE Trans On Components, Packaging, and Manufacturing Technology, 1992, 15(4): 418-425.

In digital products, flexible boards are often used. For example, in a flexible circuit board (FPC) in a flip or slide type mobile phone, electrical connection between different circuits in a digital product can be realized, and the relative displacement of each part of the digital product can be repeated. The flexible printed circuit board (FPC) is usually made of a flexible copper clad laminate (FCCL) using a polyester (PET) film or a polyimide film (PI) film as an insulating layer, and has the property of being repeatedly bendable. However, the cost of the flexible copper clad laminate (FCCL) is relatively high. In some digital products, the flexible circuit board is only flexed once during assembly and remains flexed thereafter. For example, in the liquid crystal display module, the signal is connected to the flexible circuit board between the TFT substrate and the hard circuit board. If a flexible circuit board (FPC) that can be repeatedly flexed is also used in the liquid crystal display module, it is not conducive to the full utilization of resources, and is not conducive to reducing production costs.

In view of the above, it is necessary to provide a circuit board substrate which is maintained in a state of being flexed once after being bent, and a method of manufacturing the same.

Hereinafter, a circuit board substrate and a method of fabricating the same will be described by way of embodiments.

A circuit board substrate comprising a first metal layer and an epoxy resin composite layer bonded to a surface of the first metal layer. The epoxy resin composite material layer is composed of an epoxy resin composite material, and the epoxy resin composite material has a viscosity of 10,000 centipoise to 30,000 centipoise. The epoxy resin composite material includes a carboxyl group-modified epoxy resin and a thermoplastic polyurethane. The thermoplastic polyurethane accounts for 6% to 20% by weight of the epoxy resin composite.

A method for fabricating a circuit board substrate as described above, comprising the steps of: preparing an epoxy resin composite material having a viscosity of 10,000 centipoise to 30,000 centipoise, and the epoxy resin composite material comprising a terminal carboxyl group a polymer-modified epoxy resin and a thermoplastic polyurethane, the thermoplastic polyurethane occupies 6% to 20% by weight of the epoxy resin composite; providing a first metal layer; compounding the epoxy resin A material is coated on the surface of the first metal layer to form an epoxy resin composite layer; and the epoxy resin composite layer is cured.

The epoxy resin composite material layer of the circuit board substrate provided by the technical solution contains thermoplastic polyurethane, can withstand a small number of flexing, and can be used for producing a circuit board which is maintained in a state of being bent after being bent once. Compared with the flexible copper clad laminates of the prior art, the production cost can be greatly reduced. The method for fabricating a circuit board substrate provided by the present technical solution can facilitate the fabrication of the circuit board substrate.

The circuit board substrate provided by the technical solution and the manufacturing method thereof will be further described in detail below with reference to the embodiments.

Referring to FIG. 1 , the technical solution provides a circuit board substrate 10 including a first metal layer 11 , an epoxy resin composite layer 12 , and a second metal layer 13 stacked in sequence.

The first metal layer 11 is used to form a conductive line during the fabrication of the circuit board. The first metal layer 11 has a first surface 110 in contact with the epoxy composite layer 12.

The second metal layer 13 is used to form a conductive line during the fabrication of the circuit board. The second metal layer 13 has a second surface 130 in contact with the epoxy composite layer 12.

In this embodiment, the first metal layer 11 and the second metal layer 13 are both copper foils having a thickness of about 10 micrometers to 25 micrometers, preferably 12 micrometers. The first metal layer 11 and the second metal layer 13 may also be made of other conductive metal materials such as silver or the like.

The epoxy resin composite layer 12 is located between the first metal layer 11 and the second metal layer 13 for electrical insulation. The thickness of the epoxy resin composite layer 12 can be set according to the actual needs of the circuit board substrate. The epoxy resin composite layer 12 has a thickness of from about 12 microns to about 80 microns, preferably 24 microns. The epoxy resin composite layer 12 is composed of an epoxy resin composite material. The epoxy resin composite has a viscosity of 10,000 centipoise to 30,000 centipoise. The epoxy resin composite material includes a carboxyl group-modified epoxy resin, a thermoplastic polyurethane, a hardener, an additive, a thickener, a solvent, a catalyst, and an antifoaming agent.

The epoxy resin modified by the terminal carboxyl group is a product obtained by copolymerization of an epoxy resin and a terminal carboxyl group polymer, that is, an epoxy group at the terminal of the epoxy resin reacts with a carboxyl group at the terminal end of the terminal carboxyl polymer. A monoester group is formed to obtain a polymer having repeating units including alternating epoxy resin repeating units and terminal carboxyl groups. Wherein, the epoxy resin may be a bisphenol A type epoxy resin, and the terminal carboxyl group polymer may be a liquid polybutadiene acrylonitrile (CTBN). In the present embodiment, the epoxy resin used in the epoxy resin has an epoxy equivalent of 180 to 195, preferably 188, and the epoxy resin of the modified carboxyl group has an epoxy equivalent of 220 to 352, preferably 244. . The weight percent of the carboxyl terminated polymer modified epoxy resin in the epoxy resin composite is from about 41% to about 54%, preferably about 49.52%.

The thermoplastic polyurethane is used to provide folding resistance to the epoxy resin composite material, thereby making the epoxy resin composite material resistant to bending. The thermoplastic polyurethane is present in the epoxy resin composite in an amount of from 6% to 20% by weight, preferably about 12.38%.

The hardener is used to harden the epoxy resin composite. In the present embodiment, the hardener used is dicyandiamine, and the hardener is present in the epoxy resin composite in a weight percentage of about 2.40% to 5.04%, preferably about 4.26%. The active hydrogen equivalent of dicyandiamine is about 20.6. In this embodiment, the weight ratio of the terminal carboxyl group-modified epoxy resin to the hardener is about 10.7 to 1 to 17 to 1.

The additive is aluminum oxide. The additive is present in the epoxy resin composite in an amount of from about 2% to about 18% by weight, preferably 12.38%.

The thickener is an off-type cerium oxide which increases the viscosity of the epoxy resin composite. The content of the thickener corresponds to the content of the epoxy resin modified with the terminal carboxyl group. The weight ratio of the thickener to the carboxyl terminated polymer modified epoxy resin is about 0.03 to 1. In this embodiment, the thickener is present in the epoxy resin composite in an amount of from about 0.01% to about 0.5% by weight, preferably about 0.50% by weight.

The solvent is Diethylene glycol monoethyl ether, and the solvent is about 18.57% by weight in the epoxy resin composite. This solvent is used to dissolve other components to form a uniform liquid dispersion.

The catalyst is 2-undecylimidazole, and the content of the catalyst corresponds to the content of the epoxy resin modified by the terminal carboxyl group. The catalyst is present in the epoxy resin composite in an amount of about 0.54% by weight.

The antifoaming agent is used to eliminate the foam in the above epoxy resin composite material, and the weight percentage of the defoaming agent in the epoxy resin composite material is about 1.86%. The antifoaming agent can be a 750C antifoaming agent produced by the commercially available Taiwan Yuzheng Company.

Preferably, in the epoxy resin composite, the weight percentage of the carboxyl group-modified epoxy resin is about 49.52%. The thermoplastic polyurethane has a weight percentage of about 12.38%. The hardener is present in an amount of about 4.26% by weight. The weight percent of the additive is about 12.38%. The weight percent of the thickener is about 0.49%. The weight percentage of the solvent is about 18.57%. The catalyst is present in an amount of about 0.54% by weight. The defoamer is present in an amount of about 1.86% by weight.

Referring to FIG. 1 to FIG. 6 , the technical solution further provides a manufacturing method of the circuit board substrate 10 as described above. The manufacturing method of the circuit board substrate 10 includes the following steps:

In the first step, an epoxy resin composite material is produced, and the epoxy resin composite material has a viscosity of 10,000 centipoise to 30,000 centipoise.

In this embodiment, the epoxy resin composite material can be produced by the following method:

First, the epoxy resin is modified with a terminal carboxyl group polymer to obtain an epoxy resin modified with a terminal carboxyl group polymer.

The terminal carboxyl group polymer and the epoxy resin were placed together in a reaction vessel, and the reaction temperature was maintained at 120 ° C, and the reaction was carried out for about 3 hours under stirring to obtain an epoxy resin modified with a terminal carboxyl group polymer. In the present embodiment, the epoxy resin used is a bisphenol A type epoxy resin having an epoxy equivalent of 188. The terminal carboxyl group polymer used may be liquid polybutadiene acrylonitrile (CTBN), and the modified epoxy resin obtained after the reaction has an epoxy equivalent of 244. After the above reaction, one epoxy group at the end of the epoxy resin and one carboxyl group at the terminal end of the terminal carboxyl group are bonded to each other, and one molecule of water is removed to obtain an ester group. Thus, the modified epoxy resin has good flexibility compared to the epoxy resin which is not modified. Of course, the epoxy resin is not limited to the bisphenol A type epoxy resin provided in the embodiment, and may be other types of epoxy resins. The terminal carboxyl group used is not limited to the liquid polybutadiene acrylonitrile provided in the present embodiment, and may be a polymer such as a terminal carboxyl group.

Then, the terminal carboxyl group-modified epoxy resin, thermoplastic polyurethane, hardener, additive, thickener, solvent, catalyst, and antifoaming agent are mixed and ground and dispersed to obtain an epoxy resin composite material. The thermoplastic polyurethane accounts for 6% to 20% by weight of the epoxy resin composite.

The terminal carboxyl group-modified epoxy resin, thermoplastic polyurethane, hardener, additive, thickener, solvent, catalyst and antifoaming agent may be ground and dispersed by a three-roll mill grinding disperser. In this embodiment, the thermoplastic polyurethane is first dissolved in a solvent to obtain a mixture, and the mixture and the carboxyl group-modified epoxy resin, the hardener, the additive, the thickener, the catalyst, and the antifoaming agent are each in accordance with the above respective contents. It is put into a three-roll type grinding and dispersing machine, and a three-roll type grinding dispersing machine is started to carry out grinding dispersion, thereby forming a uniformly dispersed epoxy resin composite material. The epoxy resin composite has a viscosity of 10,000 centipoise to 30,000 centipoise. In the present embodiment, among the above components, the weight percentage of the epoxy group-modified epoxy resin is about 49.52%. The thermoplastic polyurethane has a weight percentage of about 12.38%. The hardener is present in an amount of about 4.26% by weight. The weight percent of the additive is about 12.38%. The weight percentage of the thickener is about 0.50%. The weight percentage of the solvent is about 18.57%. The catalyst is present in an amount of about 0.54% by weight. The defoamer is present in an amount of about 1.86% by weight.

Referring to FIG. 2, the second step, the first metal layer 11 is provided.

The first metal layer 11 is a copper foil having a thickness of about 12 microns. The first metal layer 11 has a first surface 110. Of course, the thickness of the first metal layer 11 can also be changed according to the actual needs of the reliability of the conductive lines of the circuit board.

Referring to FIG. 3, in the third step, the epoxy resin composite material is coated on the surface of the first metal layer 11 to form a first epoxy resin composite material layer 120.

In this embodiment, a liquid epoxy resin composite material is applied to the first surface 110 of the first metal layer 11 by a slit coater to form a first epoxy resin composite material layer 120. In the present embodiment, since the coating is performed by a slit coater, the thickness of the formed first epoxy resin composite material layer 120 can be controlled to be satisfactory and the coating layer is uniform. The first epoxy resin composite layer 120 is formed to have a thickness of 6 micrometers to 40 micrometers. In this embodiment, the first epoxy resin composite layer 120 has a thickness of 12 micrometers.

Referring to FIG. 4, the fourth step, a second metal layer 13 is provided.

The second metal layer 13 is also a copper foil and has a thickness of 12 microns. The second metal layer 13 has a second surface 130. Of course, the thickness of the second metal layer 13 can also be changed according to the actual needs of the reliability of the conductive lines of the circuit board.

Referring to FIG. 5 and the fifth step, a second epoxy resin composite layer 121 is formed on the surface of the second metal layer 13.

In this embodiment, a liquid epoxy resin composite material is applied to the second surface 130 of the second metal layer 13 by a slit coater to form a second epoxy resin composite material layer 121. In the present embodiment, since the coating is performed by the slit coater, the thickness of the formed second epoxy resin composite material layer 121 can be controlled to be satisfactory and the coating layer is uniform. The second epoxy resin composite layer 121 is formed to have a thickness of 6 to 40 μm. In this embodiment, the thickness of the second epoxy resin composite material layer 121 is 12 micrometers.

Referring to FIG. 6, in the sixth step, the first metal layer 11 formed with the first epoxy resin composite material layer 120 is pressed against the second metal layer 13 on which the second epoxy resin composite material layer 121 is formed, and The first epoxy resin composite layer 120 on the surface of the first metal layer 11 and the second epoxy resin composite layer 121 on the surface of the second metal layer 13 are pressed together. Specifically, the following steps can be taken:

First, the first epoxy resin composite material layer 120 and the second epoxy resin composite material layer 121 are pre-baked. The first epoxy resin composite material layer 120 and the second epoxy resin composite material layer 121 are prebaked at 80 degrees Celsius to 90 degrees Celsius for about 15 minutes, so that the first epoxy resin composite material layer 120 and the second epoxy resin A part of the solvent in the resin composite material layer 121 volatilizes and is in a semi-cured state.

Then, the first metal layer 11 is separated from the second metal layer 13, and the first epoxy resin composite layer 120 and the second epoxy resin composite material layer 121 are opposed to each other, and the first ring of the surface of the first metal layer 11 is used by the roller. The oxy-resin composite material layer 120 is pressed together with the second epoxy resin composite material layer 121 on the surface of the second metal layer 13. In this embodiment, the temperature controlled during pressing is 100 degrees Celsius, the pressing rate is 2 meters per minute, and the pressure at the time of pressing is 0.4 to 2.5 MPa. After the pressing, the first metal layer 11, the first epoxy resin composite material layer 120, the second epoxy resin composite material layer 121, and the second metal layer 13 are integrated.

It can be understood that the prebaking duration and temperature can be determined according to the thickness of the actual first epoxy resin composite layer 120 and the second epoxy resin composite layer 121. When the thickness is large, the processing time may be appropriately extended or the temperature may be appropriately increased, and when the thickness is small, the processing time may be appropriately shortened or the temperature may be appropriately lowered to ensure the first epoxy resin composite material layer 120 and The second epoxy resin composite layer 121 can form a semi-cured film-like structure.

In the seventh step, the first epoxy resin composite material layer 120 and the second epoxy resin composite material layer 121 are cured to obtain the circuit board substrate 10 as shown in FIG.

In this embodiment, the first epoxy resin composite material layer 120 and the second epoxy resin composite material layer 121 are cured by a curing treatment. When the aging treatment was carried out, the temperature of the aging treatment was 180 ° C, and the aging treatment time was 90 minutes. After the aging treatment, the first epoxy resin composite material layer 120 and the second epoxy resin composite material layer 121 form the epoxy resin composite material layer 12 as shown in FIG. 1 and closely bond the first metal layer 11 and the first The two metal layers 13 are obtained to obtain the circuit board substrate 10.

In order to obtain the circuit board substrate 10 having different bending resistance, it can be controlled by changing the weight content of the thermoplastic polyurethane in the epoxy resin composite. When the folding test was carried out, the pressure was 0.2 MPa and the pressure was reduced by 360 degrees for 5 minutes, and the obtained circuit board substrate 10 was subjected to 5 or more times and remained intact without being broken.

Of course, in the above manufacturing process, after the third step, a second metal layer 13 may be provided, and the second metal layer 13 may be directly pressed against the epoxy resin composite formed on the first metal layer 11. On the material layer, the epoxy resin composite material layer is cured, and the circuit board substrate 10 can also be obtained.

The epoxy resin composite material layer of the circuit board substrate provided by the technical solution contains thermoplastic polyurethane, can withstand a small number of flexing, and can be used for producing a circuit board which is maintained in a state of being bent after being bent once. Compared with the flexible copper clad laminates of the prior art, the production cost can be greatly reduced. The method for fabricating a circuit board substrate provided by the present technical solution can facilitate the fabrication of the circuit board substrate.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

10‧‧‧Circuit board

11‧‧‧First metal layer

110‧‧‧ first surface

12‧‧‧Epoxy composite layer

120‧‧‧First epoxy resin composite layer

121‧‧‧Second epoxy composite layer

13‧‧‧Second metal layer

130‧‧‧ second surface

1 is a cross-sectional view of a circuit board substrate provided by an embodiment of the present technical solution.

2 is a schematic structural view of a first metal layer provided by an embodiment of the present technical solution.

3 is a schematic view showing the structure of the first epoxy resin composite layer formed on the first metal layer.

4 is a schematic structural view of a second metal layer provided by an embodiment of the present technical solution.

FIG. 5 is a schematic view showing the structure of the second epoxy resin composite layer formed on the second metal layer.

Fig. 6 is a schematic view showing the structure in which a first metal layer on which a first epoxy resin composite layer is formed and a second metal on which a second epoxy resin composite layer is formed are laminated.

10‧‧‧Circuit board

11‧‧‧First metal layer

110‧‧‧ first surface

12‧‧‧Epoxy composite layer

13‧‧‧Second metal layer

130‧‧‧ second surface

Claims (10)

A circuit board substrate comprising a first metal layer and an epoxy resin composite material layer bonded to a surface of the first metal layer, the epoxy resin composite material layer being composed of an epoxy resin composite material, the epoxy resin composite The viscosity of the material is from 10,000 centipoise to 30,000 centipoise, and the epoxy resin composite material comprises an epoxy resin modified with a terminal carboxyl group polymer and a thermoplastic polyurethane, and the thermoplastic polyurethane is occupied by the epoxy resin composite material. The weight percentage is 6% to 20%. The circuit board substrate according to claim 1, wherein the terminal carboxyl group-modified epoxy resin is a liquid polybutadiene acrylonitrile modified bisphenol A type epoxy resin. The circuit board substrate of claim 1, wherein the epoxy resin composite material further comprises a hardener, the hardener is dicyandiamide, the terminal carboxyl polymer modified epoxy The weight ratio of the resin to the hardener is 10.7 to 1 to 17 to 1. The circuit board substrate of claim 1, wherein the epoxy resin composite material further comprises an additive and a thickener, the additive is aluminum oxide, and the thickener is ionized. The type of cerium oxide, the weight ratio of the thickener to the additive is 0.03 to 1. The circuit board substrate of claim 4, wherein the epoxy resin composite material further comprises a solvent, a catalyst and an antifoaming agent, the solvent is diethylene glycol diethyl ether, and the catalyst is 2 - undecyl imidazole. The circuit board substrate of claim 1, wherein the circuit board substrate further comprises a second metal layer attached to a surface of the epoxy resin composite material layer, wherein the epoxy resin composite material layer is located Between the first metal layer and the second metal layer, the materials of the first metal layer and the second metal layer are both copper. A method for manufacturing a circuit board substrate, comprising the steps of:
Making an epoxy resin composite material having a viscosity of 10,000 centipoise to 30,000 centipoise, the epoxy resin composite material comprising a carboxyl group-modified epoxy resin and a thermoplastic polyurethane, the thermoplastic The weight percentage of the polyurethane in the epoxy resin composite material is 6% to 20%;
Providing a first metal layer;
Applying the epoxy resin composite to the surface of the first metal layer to form an epoxy resin composite layer; and curing the epoxy resin composite layer. The method for fabricating a circuit board substrate according to claim 7, wherein the step of preparing the epoxy resin composite material comprises the steps of:
The epoxy resin is modified with a terminal carboxyl group polymer to obtain an epoxy resin modified with a terminal carboxyl group polymer; and the epoxy resin modified with the terminal carboxyl group polymer is mixed with a thermoplastic polyurethane and ground and dispersed to obtain a ring. Oxygen resin composite. The method for fabricating a circuit board substrate according to claim 7, wherein after the epoxy resin composite material is applied to the first metal layer, before the curing the epoxy resin composite material layer, the steps are included :
Providing a second metal layer; and laminating the second metal to a surface of the epoxy resin composite layer such that the epoxy resin composite layer is between the first metal layer and the second metal layer. The method for fabricating a circuit board substrate according to claim 7, wherein after the epoxy resin composite material is applied to the first metal layer, before the curing the epoxy resin composite material layer, the steps are included :
Providing a second metal layer;
Coating a surface of the second metal layer to form another epoxy resin composite layer; and laminating the first metal formed with the epoxy resin composite layer to the second layer formed with another epoxy resin composite layer The metal layer is laminated with the epoxy resin composite layer on the surface of the first metal layer and another epoxy resin composite material on the surface of the second metal layer.