TWI669031B - Composite metal substrate and method for manufacturing the same and circuit board - Google Patents

Abstract

A composite metal substrate comprising: a core layer; a roughened layer formed on the core layer; and a composite metal layer formed on the roughened layer, the rough layer being sandwiched The composite metal layer is interposed between the core layer and the core layer, wherein the composite metal layer comprises a silver layer, a nickel layer and a copper layer. The present invention provides a circuit board having the composite metal substrate.

Description

 Composite metal substrate and its preparation method and circuit board  

The present invention relates to a composite metal substrate, and more particularly to a composite metal substrate for a flexible printed wiring board and a method of fabricating the same.

The development of electronics and optoelectronics industry is changing with each passing day. Electronic products are fast, light, thin and short. Printed circuit boards are also facing the challenges of high precision, high density and thin line. In recent years, with the rapid development of display screens such as 4G, 5G, 6G, 2K or 4K, the driving flexible circuit board must be smaller and smaller, and some passive components can be integrated on the circuit board, so that the requirements for the circuit board Not only the system needs to be miniaturized, but also the assembly density of the circuit is increased, and the reliability of the system needs to be improved.

At present, in order to meet the needs of processing thin wire processing, most of the two methods are etched copper or semi-additive. Among them, the copper thinning method is to etch the original thick copper foil by etching process. A part of the copper foil is required to be thinned, but in actual production operations, we have found that this method requires very high etching uniformity, and a slight inattention may result in incomplete etching and short circuit caused by copper residual.

Therefore, most of the current nano copper substrate manufacturers use the semi-additive method to manufacture, in order to meet the needs of thin line processing, and the semi-additive method is divided into two methods: copper plating method and carrier copper method. Among them, the copper plating method uses the pre-drilling of the polyimine film, and the plasma treatment and ultrasonic cleaning of the surface of the PI (polyimine) and the surface of the pore wall are performed to achieve the purpose of roughening the surface. Then, the PI surface and the pore wall are plated with a catalyst layer by means of a catalyst, such as chromium, palladium, nickel, carbon or the like, or an alloy layer thereof, and then the thickness of the copper substrate is increased by electroless plating of copper. However, such a process is prone to abnormalities such as hole breakage and pits caused by the bite of the through hole during chemical roughening. In particular, copper plating is likely to occur due to black hole plating, resulting in reliability, size, peel strength, and the like. . In addition, when the copper plating method is used, in order to meet the bonding force, after the completion of the first layer of the catalyst layer, heat treatment is needed to improve the adhesion between the conventional metal layer and the polyimide layer, but the substrate is affected. The dimensional stability.

In the carrier copper method, although the carrier layer protects the copper foil from scratches and scratches, it is easy to cause processing difficulties and stress residual during peeling when peeling off the carrier layer, and the copper foil is likely to be deformed and the dimensional expansion and contraction is greatly changed; Ultra-thin copper foil is not easy to process and will increase processing costs.

Therefore, there has still been a need to develop a metal substrate which can be used for a thin high-density circuit and which has good dimensional stability and peel strength, and which is easy to process, and a method for producing the same.

The present invention provides a method for manufacturing a composite metal substrate, the method comprising: forming a through hole penetrating through the core layer in a core layer having opposite surfaces; forming opposite sides on opposite surfaces of the core layer a two-layer roughening layer of the first surface and the second surface, and each of the roughening layers is in contact with the core layer by the second surface; and forming a composite metal layer on the roughened layer to sandwich the roughened layer Between the composite metal layer and the core layer, and the composite metal layer includes a silver layer, a nickel layer and a copper layer. The present invention provides a composite metal substrate comprising a core layer having opposite surfaces; and two rough layers having opposite first and second surfaces, respectively formed on opposite surfaces of the core layer, And each of the roughened layers is in contact with the core layer by the second surface; and a two-layer composite metal layer is formed on each of the roughened layers, and the roughened layer is sandwiched between the composite metal layer and the core layer Between the two, the composite metal layer includes a silver layer, a nickel layer and a copper layer.

The invention also provides a method for manufacturing a composite metal circuit board, comprising: forming a photoresist layer on at least one surface of the composite metal substrate of the invention; patterning the photoresist layer to self-pattern the photoresist layer Exposing the composite metal layer; removing the exposed composite metal layer and the patterned photoresist layer to form a wiring layer; and plating copper on the wiring layer to increase the thickness of the wiring layer.

In one embodiment of the invention, the step of forming the via is performed by ultraviolet light (UV) or mechanical drilling on the core layer to form a through hole for the fabrication of a flexible printed circuit board (FPC).

In a specific embodiment of the method for producing a composite metal substrate of the present invention, the first surface of the roughened layer has a surface roughness (Rz) of 50 to 800 nm.

In a specific embodiment of the method for manufacturing a composite metal substrate of the present invention, the composite metal layer is formed on the roughened layer, and a composite metal layer is formed in the through hole as a conductive path of the composite metal substrate. hole.

In still another embodiment of the method for fabricating a composite metal substrate of the present invention, the conductive paste is filled in the through hole to form a conductive pillar penetrating the composite metal substrate before forming the composite metal layer.

In a specific embodiment of the composite metal substrate of the present invention and the method for producing the same, the composite metal layer is in contact with the rough layer by the silver layer.

In a specific embodiment of the composite metal substrate of the present invention and the method for fabricating the same, in the composite metal layer, the silver layer, the nickel layer and the copper layer are sequentially arranged according to the silver layer, the copper layer and the nickel layer, that is, the copper layer is located Between the silver layer and the nickel layer.

In a specific embodiment of the composite metal substrate of the present invention and a method for producing the same, the composite metal layer has a thickness of 100 to 800 nm.

In a specific embodiment of the composite metal substrate of the present invention and the method for producing the same, the thickness of the roughened layer is 2 to 5 μm, respectively.

In a specific embodiment of the composite metal substrate of the present invention and a process for producing the same, the roughened layer has a surface roughness (Rz) of 50 to 800 nm.

In one embodiment of the composite metal substrate of the present invention and a method of making the same, the core layer has a thickness of from 12.5 to 100 microns.

In a specific embodiment of the composite metal substrate of the present invention and a process for producing the same, the core layer has a coefficient of thermal expansion of 4 to 19 ppm/°C.

In the composite metal substrate of the present invention and the method for fabricating the same, the composite metal layer comprising at least a silver layer, a nickel layer and a copper layer is transparently formed by the present invention to avoid pore breakage caused by chemically puncturing the pore walls of the metal substrate. Abnormalities such as pits (for example, avoiding carbon residue, etc.), improving dimensional stability and peel strength, not only can reduce the FPC drilling process, shorten the production cycle, but also improve the product yield of the obtained circuit board.

1, 1'‧‧‧ composite metal substrate

10‧‧‧ core layer

100‧‧‧through holes

11‧‧‧ rough layer

11a‧‧‧ first surface

11b‧‧‧ second surface

12,12’‧‧‧Composite metal layer

121,221‧‧‧ silver layer

122, 222‧‧‧ copper layer

123,223‧‧‧ Nickel layer

13‧‧‧Electrical through holes

13’‧‧‧conductive column

2‧‧‧Composite metal circuit board

20‧‧‧ patterned photoresist layer

200‧‧‧ photoresist layer

21‧‧‧ copper

22‧‧‧Line layer

M‧‧‧ mask

1A to 1D are views showing a method of manufacturing a composite metal substrate of the present invention, wherein a first embodiment of the present invention is a schematic view of another embodiment of the composite metal substrate of the present invention; and FIGS. 2A to 2E are diagrams showing the present invention. Schematic diagram of the method of manufacturing a composite metal circuit board.

The other embodiments of the present invention will be readily understood by those skilled in the art from this disclosure.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered. In the meantime, the terms "a" and "an" are used in the specification for the purpose of description and are not intended to limit the scope of the invention. The following is also considered to be an area in which the invention can be implemented.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate the other advantages and advantages of the present invention. The present invention may be embodied or applied in various other specific embodiments, and various modifications and changes may be made without departing from the spirit and scope of the invention.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered.

Please refer to FIGS. 1A to 1D for a schematic view showing the process of the composite metal substrate of the present invention.

As shown in FIG. 1A, the method for fabricating a composite metal substrate of the present invention comprises forming a through hole 100 penetrating the core layer 10 in a core layer 10 having opposite surfaces.

In the embodiment, the through hole 100 is formed by forming the through hole 100 on the core layer 10 by ultraviolet light (UV) or mechanical drilling. In one embodiment, the through hole 100 is used to make a hole required for a flexible printed circuit board.

In the present embodiment, the core layer 10 has a thickness of 12.5 to 100 microns. In a more preferred embodiment, the core layer 10 has a thickness of 12.5 to 50 microns.

In the present embodiment, the material of the core layer 10 is a polymeric material having a low coefficient of thermal expansion (CTE). For example, the material forming the core layer 10 is a polyimide having a low coefficient of thermal expansion. In the foregoing embodiment, the core layer 10 has a coefficient of thermal expansion of 4 to 19 ppm/°C, more preferably 4 to 11 ppm/°C. When the present invention uses a polyimine having a low coefficient of thermal expansion as the core layer 10, the coefficient of thermal expansion coefficient of the composite metal substrate of the present invention can be lowered to reduce the size expansion of the composite metal substrate and improve the dimensional stability thereof. Suitable for applications with ultra-fine lines.

As shown in FIG. 1B, a roughened layer 11 having a first surface 11a and a second surface 11b opposite to each other is formed on the core layer 10, and the second surface 11b is in contact with the core layer 10.

In the present embodiment, the roughened layer 11 has a thickness of 2 to 5 μm. In this embodiment, the roughened layer 11 has a surface roughness (Rz) of 50 to 800 nm. Specifically, the first surface 11a has a surface roughness of 50 to 800 nm. In a more preferred embodiment, the first A surface 11a has a surface roughness of 80 to 800 nm.

In the present invention, the material for forming the rough layer 11 includes a material for forming the core layer. For example, when the material of the core layer 10 is formed of polyimine, the rough layer 11 is formed. Materials include polyimine and additives.

In the present embodiment, the material for forming the rough layer 11 is polyimine and the additive, and the content of the additive is 3 to 45% by weight, more preferably, based on the total weight of the rough layer 11. It is 5 to 15% by weight and is subjected to surface roughening treatment to obtain a roughened surface (first surface 11a).

In the present embodiment, the surface roughening treatment is performed by a process such as surface corona treatment, plasma treatment, or powder roughening of the surface. In the foregoing embodiment, the additive is an inorganic powder or a flame retardant compound, and the inorganic powder system is ceria, titania, alumina, aluminum hydroxide or calcium carbonate, and the flame retardant compound is contained. a flame retardant compound of a halogen, phosphorus, nitrogen or boron type, wherein the additive is an inorganic powder, and the content of the inorganic powder is from 3 to 45% by weight based on the total weight of the roughened layer, When the additive is a flame retardant compound, the flame retardant compound is contained in an amount of from 3 to 45% by weight based on the total weight of the roughened layer.

The roughening layer 11 of the present invention through the first surface 11a having a roughness of 50 to 800 nm is used to increase the adhesion with the composite metal layer 12 when the composite metal layer 12 is subsequently disposed (see FIG. 1C), when the present invention The roughening layer 11 is surface-modified by the surface powder, and the surface of the rough layer 11 can be raised to enhance the adhesion between the first surface 11a and the composite metal layer 12, and the coarse layer 11 contains inorganic powder. When the body or the flame retardant compound layer has a good adhesion, it can enhance the hardness or flame retardancy of the roughened layer.

As shown in Fig. 1C, a composite metal layer 12 is formed on the roughened layer 11, and the roughened layer 11 is interposed between the composite metal layer 12 and the core layer 10 to obtain a composite metal substrate 1 of the present invention.

In the embodiment, the composite metal layer 12 includes a silver layer 121, a copper layer 122, and a nickel layer 123.

In this embodiment, the silver layer 121 is in contact with the first surface 11a of the roughened layer 11, and a copper layer 122 is formed on the silver layer 121, and finally the material is on the outer side of the composite metal layer 12, that is, A nickel layer 123 is formed away from one side of the roughened layer 11.

In the present invention, the composite metal layer 12 is formed by sputtering or electroplating.

In the present embodiment, the composite metal layer 12 is formed on the roughened layer 11, and the composite metal layer 12 is formed in the through hole 100, so that the composite metal layer 12 is formed on the roughened layer 11 In the hole 100, the conductive metal via 1 is formed as a conductive via 13 of the composite metal substrate 1, and the conductive via 13 is electrically connected to the opposite sides of the composite metal substrate 1. In the foregoing embodiment, the conductive via 13 is formed by a hole wall metal plating method.

In one embodiment, the composite metal layer 12 has a total thickness of from 100 to 800 nm. In the foregoing embodiment, the silver layer 121 and the nickel layer 123 are each 5 nm or more, preferably the silver layer is 5 to 15 nm, and the nickel layer is 5 to 15 nm, in the composite metal layer. The copper layer is 90 nm or more, and preferably the copper layer is 90 to 150 nm.

In this embodiment, the copper layer 122 in the composite metal layer is protected from oxidation by the silver layer 121 and the nickel layer 123 having a thickness of 5 to 15 nm to enhance the patterned electrical properties of the composite metal layer. The reliability of the connection.

The composite metal layer 12 of the present embodiment is in contact with the first surface 11a of the roughened layer 11 through the silver layer 121, so that the composite metal layer 12 has a good bonding strength. Therefore, the composite metal layer of the embodiment is sequentially formed. The silver layer 121, the copper layer 122, and the nickel layer 123 have both good adhesion strength, electrical connection effect, and reliability.

Referring to FIG. 1C′, in another embodiment of the present invention, the composite metal layer 12 is formed only on the roughened layer 11 and is not formed in the through hole 100. In this case, the composite metal substrate of the present invention is prepared. The intermediate layer includes a conductive paste filled in the through hole 100 to serve as the conductive pillar 13' of the composite metal substrate.

In the present embodiment, the method of forming the conductive pillar 13' is through the screen printing, so that the conductive paste penetrates into the pre-made through hole 100, and the capillary hole is used to make the through hole 100. The conductive paste of the pillar or rivet structure is filled and then baked to cure to form interconnect vias.

In the foregoing embodiments, the conductive paste is formed of an epoxy resin and conductive particles in an amount of 5 to 55% by weight, the conductive particles being copper, silver, nickel, carbon or a combination thereof.

As shown in FIG. 1D, after forming the conductive pillar 13' penetrating the composite metal substrate 1', a composite metal layer is formed on the opposite end faces (not labeled) of the roughened layer 11 and the conductive pillar 13'. 12', the roughened layer 11 is sandwiched between the composite metal layer 12' and the core layer 10, and the conductive pillar 13' is sandwiched in the composite metal layer 12' to obtain another embodiment of the present invention. Composite metal substrate 1'.

Moreover, when the thickness of the composite metal layer of the present invention is 100 to 200 nm, the line width (or line pitch) of the wiring layer of the wiring board made of the composite metal substrate of the present invention can reach 15 μm, or even It is 10 micrometers, and more preferably, the line width (or line pitch) can be less than 10 micrometers to meet the requirements of fine lines, and can better meet the requirements for thinning of FPC or COF substrates, and meet the production requirements of FPC manufacturers. Improve product yields and reduce processing costs for FPC manufacturers.

The present invention provides a method for manufacturing a composite metal wiring board, the method comprising forming a photoresist layer on the composite metal substrate of the present invention; patterning the photoresist layer to expose the patterned photoresist layer a composite metal layer; removing the exposed composite metal layer and the patterned photoresist layer to form a wiring layer; and plating copper on the wiring layer to increase the thickness of the wiring layer.

Please refer to FIGS. 2A to 2E for a schematic view showing the manufacturing method of the composite metal wiring board of the present invention.

The photoresist layer 200 is formed on at least one surface of the composite metal substrate 1 (see FIG. 1C) of the present invention as shown in FIG. 2A.

In the present embodiment, a negative photoresist is taken as an example, and a negative photoresist is formed on the composite metal substrate 1 of the present invention, and the photoresist layer 200 is exposed in the presence of the patterned mask M.

As shown in FIG. 2B, the photoresist layer 200 is patterned to expose the composite metal layer from the patterned photoresist layer.

In this embodiment, the mask M and the photoresist layer shielded by the mask M are removed, that is, the patterned photoresist layer 20 is obtained.

As shown in FIG. 2C, the composite metal layer 12 not covered by the patterned photoresist layer 20 is removed by etching.

As shown in FIG. 2D, the patterned photoresist layer 20 is removed to obtain the wiring layer 22.

In the embodiment, the wiring layer 22 includes a silver layer 221, a copper layer 222, and a nickel layer 223.

In the present embodiment, the wiring layer 22 has a total thickness of 100 to 800 nm. In the foregoing embodiment, the silver layer 221 and the nickel layer 223 are each 5 nanometers or more, preferably, the silver layer 221 is 5 to 15 nanometers, and the nickel layer 223 is 5 to 15 nanometers. The copper layer 222 in layer 22 is 90 nanometers or more, and preferably the copper layer is 90 to 150 nanometers.

As shown in FIG. 2E, copper 21 is plated on the wiring layer 22 to increase the thickness of the wiring layer 22.

In the present embodiment, copper is plated on the wiring layer 22 by sputtering or electroplating, and the thickness of the wiring layer 22 is increased to obtain the composite metal wiring board 2 of the present invention.

In the composite metal substrate, the composite metal wiring board and the method for manufacturing the same according to the present invention, the composite metal layer including at least a silver layer, a nickel layer and a copper layer is passed through the physical preparation method to avoid chemical biting of the hole wall of the metal substrate. Abnormalities such as hole breaks and pits caused by etch (for example, avoiding carbon residue, etc.), improve dimensional stability and peel strength, not only reduce FPC drilling process, shorten production cycle, but also improve the circuit board produced. Product yield.

When the thickness of the composite metal layer of the present invention is from 100 to 200 nm, the line width (or line pitch) of the wiring layer of the wiring board made of the composite metal substrate of the present invention can reach 15 μm, or even 10 μm. It is better that the line width (or line spacing) can be less than 10 micrometers to meet the requirements of fine lines, and can better meet the requirements for thinning of FPC or COF substrates, meet the production requirements of FPC manufacturers, and improve FPC manufacturing. Manufacturer's product yield, reducing processing costs.

The above-described embodiments are merely illustrative of the effects of the present invention, and are not intended to limit the present invention, and those skilled in the art can implement the above-described embodiments without departing from the spirit and scope of the present invention. Make modifications and changes. In addition, the number of elements in the above-described embodiments is merely illustrative and is not intended to limit the invention. Therefore, the scope of protection of the present invention should be as set forth in the appended claims.

Claims (12)

A method for manufacturing a composite metal substrate, the method comprising: forming a through hole penetrating through the core layer in a core layer having opposite surfaces; and modifying the surface through the surface powder on opposite surfaces of the core layer Forming two layers of roughened layers having opposite first and second surfaces, respectively, and each of the roughened layers is in contact with the core layer by the second surface, wherein a surface of the first surface of the roughened layer is rough a degree of (Rz) of 50 to 800 nm; and forming a composite metal layer on the roughened layer, the roughened layer is sandwiched between the composite metal layer and the core layer, and the composite metal layer includes a silver layer, Nickel and copper layers. The method of manufacturing a composite metal substrate according to claim 1, wherein the through hole is formed on the core layer by ultraviolet light (UV) or mechanical drilling. The method for manufacturing a composite metal substrate according to claim 1, wherein the composite metal layer is formed on the rough layer, and a composite metal layer is formed in the through hole to serve as a conductive layer of the composite metal substrate. hole. The method for manufacturing a composite metal substrate according to claim 1, wherein before the forming the composite metal layer, the conductive paste is filled in the through hole to form a conductive pillar penetrating the composite metal substrate. A composite metal substrate comprising: a core layer having opposite surfaces; a two-layer roughening layer having a first surface and a second surface, respectively, formed on opposite surfaces of the core layer, and each of the roughening layers is in contact with the core layer by the second surface, wherein The roughening layer includes a surface powder, and a surface roughness (Rz) of the first surface of the roughened layer is 50 to 800 nm; and a two-layer composite metal layer is formed on each of the roughened layers, respectively The roughening layer is sandwiched between the composite metal layer and the core layer, wherein the composite metal layer comprises a silver layer, a nickel layer and a copper layer. The composite metal substrate according to claim 5, wherein the composite metal layer is in contact with the rough layer by the silver layer. The composite metal substrate of claim 6, wherein the copper layer is between the silver layer and the nickel layer. The composite metal substrate according to claim 5, wherein each of the composite metal layers has a thickness of 100 to 800 nm. The composite metal substrate according to claim 5, wherein each of the roughened layers has a thickness of 2 to 5 μm. The composite metal substrate according to claim 5, wherein the core layer has a thickness of 12.5 to 100 μm. The composite metal substrate according to claim 5, wherein the core layer has a thermal expansion coefficient of 4 to 19 ppm/°C. A method for manufacturing a composite metal wiring board, comprising: forming a photoresist layer on at least one surface of a composite metal substrate as described in claim 5; patterning the photoresist layer to be self-patterned Exposure in the photoresist layer Exposing the composite metal layer; removing the exposed composite metal layer and the patterned photoresist layer to form a wiring layer; and plating copper on the wiring layer to increase the thickness of the wiring layer.