TWI548315B - Circuit substrate, method for making the same, and circuit board and electronic device using the same. - Google Patents

Description

Circuit substrate and manufacturing method thereof, circuit board and electronic device

The present invention relates to a method of fabricating a circuit board, a circuit board produced by the method, a circuit board to which the circuit board is applied, and an electronic device to which the circuit board is applied.

In recent years, flexible circuit boards have become more and more widely used in electronic products. The circuit board of the flexible circuit board is usually fabricated by a subtractive process, that is, a copper film on the surface of the copper layer is covered with a dry film photoresist layer, and then subjected to an exposure and development process to transfer the required line pattern to the photoresist layer. Then, the patterned photoresist layer is used as a mask, and the exposed copper layer is wet-etched to form a desired conductive line on the copper layer. However, the conventional subtractive process usually has a side etching phenomenon, that is, the copper layer is incompletely etched away from the bottom of the photoresist layer or the top is excessively etched, so that the cross-sectional profile of the conductive line on the copper layer produced by the method is generally narrow. The wide trapezoidal structure will make the line width of the prepared conductive line larger, so that the thickness of the copper layer needs to be reduced to a particularly small size to obtain a conductive line with a small line width. In addition, the bonding force between the conductive circuit of the conventional circuit substrate and the copper clad laminate substrate is not large enough.

In view of the above, it is necessary to provide a method of fabricating a circuit substrate capable of improving the bonding force between a conductive line and a substrate.

Further, it is also necessary to provide a circuit board produced by the above-described method of manufacturing a circuit board.

In addition, it is also necessary to provide a circuit board to which the circuit substrate is applied.

In addition, it is also necessary to provide an electronic device to which the circuit board is applied.

A method of fabricating a circuit substrate, comprising the steps of: providing a substrate comprising at least a surface of a polyimine having -COOH; forming an unactivated catalytic metal ion and photoinitiating on the surface of the substrate The unactivated catalyst layer of the agent, chemically reacts the unactivated catalytic metal ions near the substrate with the polyethylenimine having -COOH on the surface of the substrate; the portion of the unactivated catalyst layer The area is exposed, so that the unactivated catalytic metal ions in the region are activated by the photoinitiator to form a catalytic metal element, and the unactivated catalytic metal ions after the bonding are also activated by the photoinitiator. The catalytic metal element is embedded in the surface of the substrate, and the exposed region is converted into an activation catalyst region, and the unexposed region is an unactivated catalyst region; and the activation catalyst region is formed The substrate is electrolessly plated with a conductive metal such that the conductive metal ions enter the activation catalyst region and are reduced to a conductive metal element under the catalysis of the catalytic metal element, thereby causing the activation catalyst region to rotate. A conductive line comprising a conductive metal element and a catalytic metal element dispersed between the elemental particles of the conductive metal, and removing the unactivated layer before the electroless plating of the conductive metal to form the conductive line or after the electroless plating of the conductive metal to form the conductive line Catalyst zone.

A circuit substrate comprising a substrate and a conductive line bonded to at least one surface of the substrate, the substrate containing at least a surface of the substrate having a polyamine of -COOH, the conductive line containing a conductive metal element and dispersed in the conductive a catalytic metal element between metal elemental particles, a part of the catalytic metal in the conductive line is embedded a surface of the substrate in contact with the conductive trace.

A circuit board comprising the above circuit substrate.

An electronic device includes at least one circuit board including the above circuit substrate.

In the method of fabricating the circuit substrate, an unactivated catalyst layer is formed on a substrate having a polyamine of -COOH on the surface, so that the unactivated catalytic metal ions near the substrate and the surface of the substrate have -COOH The polyimine is chemically bonded to bond, and a part of the unactivated catalytic metal ion is activated to form a catalytic metal element, and the unactivated catalytic metal ion after the bonding is also under the action of a photoinitiator. Activating a catalytic metal element and embedding the surface of the substrate, and converting the activation catalyst region into a conductive line by chemical plating, thereby preparing a conductive line including a catalytic metal element and a conductive metal element, and A part of the catalytic metal element of the conductive line is embedded on the surface of the substrate in contact with the conductive line, so that the bonding force between the conductive line and the substrate is strong. In addition, the method for fabricating the above circuit substrate does not need to use the dry film photoresist layer in the usual subtractive process, thereby facilitating the occurrence of side etching, simple process, and resource saving.

10‧‧‧ Polyimine film

100‧‧‧ circuit board

10‧‧‧Substrate

11‧‧‧ Carrier Board

12‧‧‧ Cover film

20‧‧‧Electrical circuit

30‧‧‧Unactivated catalyst layer

40‧‧‧Transition layer

41‧‧‧Activation catalyst zone

42‧‧‧Unactivated catalyst zone

200‧‧‧ mask

201‧‧‧Lighting hole

400‧‧‧Electronic devices

401‧‧‧shell

402‧‧‧ screen

Figure 1 is a schematic view of a substrate.

2 is a schematic view showing the bonding of an unactivated catalyst layer on the surface of the substrate shown in FIG. 1.

3 is a schematic view showing exposure of the unactivated catalyst layer shown in FIG. 2.

4 is a schematic view of a transition layer formed after exposure of the unactivated catalyst layer shown in FIG.

Fig. 5 is a schematic view showing the removal of the unactivated catalyst region of the transition layer shown in Fig. 4.

Figure 6 is a circuit board in accordance with a preferred embodiment of the present invention.

FIG. 7 is a schematic diagram of an electronic device according to a preferred embodiment of the present invention.

Referring to FIG. 6, the present invention provides a circuit substrate 100 for fabricating a circuit board (not shown). The circuit substrate 100 includes a substrate 10 and a patterned conductive line 20 bonded to at least one surface of the substrate 10. The conductive line 20 contains a simple substance of a conductive metal and a catalytic metal element which is dispersed between the elemental particles of the conductive metal and has catalytic activity for reducing the conductive metal ion. A part of the catalytic metal element of the conductive line 20 is embedded on the surface of the substrate 10 that is in contact with the conductive line 20, thereby effectively improving the bonding force between the conductive line 20 and the substrate 10.

The conductive metal element is a single element of a conductive metal such as a simple substance of copper metal, a simple substance of nickel metal, and a simple substance of silver metal, which is conventionally applied to a circuit board, and is preferably a simple substance of copper metal.

The catalyst metal element is a conventional catalytic metal element such as a palladium metal element, a gold metal element, a nickel metal element, or a cobalt metal element, and is preferably a palladium metal element.

In the embodiment, the substrate 10 includes a carrier 11 and a cover film 12 bonded to at least one surface of the carrier 11 . Each conductive line 20 is bonded to a surface of the cover film 12 away from the carrier 11 .

The material of the carrier 11 may be selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate, polyether ether ketone, polyfluorene, polyether oxime, polycarbonate, polyamine, poly One of insulating resins conventionally used for circuit boards, such as quinone imine, acrylic resin, and trivinyl cellulose.

The cover film 12 is a polyimide film (PI film) containing a polyimine (-hereinafter referred to as PI-COOH) having -COOH (carboxyl group). The structural formula of the PI-COOH is:

Wherein X ₁ and X ₃ are organofunctional groups having four covalent bonds, X ₁ and X ₃ may be the same or different; X ₂ and X ₄ are organofunctional groups having a double covalent bond, X ₂ and X ₄ They may be the same or different; m and n are the number of repeating units, wherein m and n are each an integer of 10 to 1000.

X ₁ and X ₃ are independently selected from one of the following functional groups: .

When X ₂ is the same as X ₄ , X ₂ and X ₄ are each selected from one of the following functional groups: . Wherein R ₁ is COOH; R _{2 is} selected from OH, ,and In one of the above, R is H or CH ₃ , p, q are integers from 1 to 20; Y _{1 is} selected from -O-, -CO-, -S-, -SO ₂ -, -CH ₂ -, -C ( CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _n1 -, -O(CH ₂ ) _n2 O-, -COO(CH ₂ ) _n3 OCO-, ,and One of them, wherein n1, n2, and n3 are integers of 1 to 10.

When X _{4 is} different from X ₂ , X _{4 is} selected from one of the following functional groups: . Wherein Y ₁ and Y ₂ are respectively selected from -O-, -CO-, -S-, -SO ₂ -, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _n1 -, -O(CH ₂ ) _n2 O-, -COO(CH ₂ ) _n3 OCO-, ,and One of them, wherein n1, n2, and n3 are integers of 1 to 10; R ₃ is H, CH ₃ , ethyl or phenyl, and r, s, and t are integers of 1 to 30.

In another embodiment, the substrate 10 is directly a polyimide substrate without including the carrier 11, and the PI-COOH is contained in the polyimide substrate.

Referring to FIG. 1 to FIG. 6 , a manufacturing method of the above circuit substrate 100 includes the following steps:

Step S1: Referring to FIG. 1, a substrate 10 is provided. At least one surface of the substrate 10 contains PI-COOH.

In the present embodiment, the substrate 10 includes a carrier 11 and a cover film 12 bonded to at least one surface of the carrier 11. The cover film 12 is a polyimide film comprising PI-COOH. In another embodiment, the substrate 10 is a polyimide substrate comprising PI-COOH.

Step S2: Referring to FIG. 2, an unactivated catalyst layer 30 is formed on one surface of the substrate 10. The unactivated catalyst layer 30 contains unactivated catalytic metal ions (Mn ⁺ ) and a photoinitiator.

Specifically, the substrate 10 is immersed in a catalyst solution containing an unactivated catalytic metal ion Mn ⁺ and a photoinitiator, and then taken out, so that the surface of the substrate 10 forms the unactivated catalyst layer 30.

The unactivated catalytic metal ion Mn ⁺ is a transition metal ion selected from one or more of a gold ion, a palladium ion, a cobalt ion, and a nickel ion, wherein n is an integer greater than zero. The photoinitiator is selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone, 2, 4, 6-trimethylbenzimidyl-diphenylphosphine oxide, benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone , tolyl mercapto derivative, benzophenone, 4-benzylidene-4'-methyl-diphenyl sulfide, methyl 2-benzylidenebenzoate, isopropyl thioxanthene (2 , 4 isomer mixture), 4-(N,N-dimethylamino)benzoic acid ethyl ester, 4-(N,N-dimethylamino)benzoic acid isooctyl ester, tertiary amine acrylate, amine modification One or more of epoxy acrylates. The photoinitiator is used to initiate activation of the unactivated catalytic metal ion Mn ⁺ upon exposure to form a catalytic metal element M.

Wherein, when the substrate 10 is in contact with the catalyst solution, the PI-COOH on the surface of the substrate 10 chemically reacts with the unactivated catalytic metal ion Mn ⁺ to form [PI-COO] _n M so as to be close to the substrate 10. The unactivated catalytic metal ion Mn ^{+ is} bonded to the substrate 10 by a chemical bond, thereby providing a strong bonding force between the unactivated catalyst layer 30 and the substrate 10.

Step S3: Referring to FIG. 3 and FIG. 4, the area of the unactivated catalyst layer 30 corresponding to the conductive line 20 is exposed, so that the unactivated catalytic metal ion Mn ^{+ of} the region acts as a photoinitiator. The lower activation forms an activated catalytic metal element M, thereby forming the region into the activation catalyst region 41. The unexposed area is the unactivated catalyst zone 42, i.e., a transition layer 40 comprising an activation catalyst zone 41 and an unactivated catalyst zone 42 is obtained.

Specifically, a patterned photomask 200 having a light-passing aperture 201 is disposed on a side of the substrate 10 having the unactivated catalyst layer 30, and the light-passing aperture 201 corresponds to an unactivated catalyst layer 30. The area of the conductive line 20. The area of the reticle 200 other than the light passing hole 201 does not allow light to pass. Then, the unactivated catalyst layer 30 is exposed, and the light emitted by the light source (not shown) is irradiated to the unactivated catalytic metal ions through the light-passing holes 201 of the mask 200 to make the unactivated catalytic metal ions in the region M. ^{The n+} is activated by the photoinitiator to form a catalytic metal element M, thereby obtaining the transition layer 40 including the activation catalyst region 41 and the unactivated catalyst region 42. The activation catalyst region 41 contains a catalytic metal element. The light emitted by the light source may be ultraviolet light, infrared light or the like that can activate the unactivated catalytic metal ion Mn ⁺ .

During the exposure process, the unactivated catalytic metal ion Mn ⁺ in the unactivated catalyst layer 30 is reduced to the catalytic metal element M, while the interface between the unactivated catalyst layer 30 and the substrate 10 is combined with PI-COO. The bound unactivated catalytic metal ion Mn ⁺ is also reduced to the catalytic metal element M and embedded on the surface of the substrate 10 in contact with the transition layer 40.

Step S4: Referring to FIG. 5, the unactivated catalyst region 42 is removed.

Specifically, the unactivated catalyst region 42 can be cleaned by a conventionally used lye to remove the unactivated catalyst layer, and then rinsed with water to remove the unactivated catalyst region 42. The lye may be an alkaline solution such as a sodium hydroxide solution or a potassium hydroxide solution which is conventionally used.

Step S5: Referring to FIG. 6, the substrate on which the activation catalyst region 41 is formed is electrolessly plated with a conductive metal to convert the activation catalyst region 41 into the conductive line 20.

Specifically, a solution containing conductive metal ions is coated or immersed in the above-mentioned activation catalyst region 41 such that the conductive metal ions enter the activation catalyst region 41 and are catalyzed by the catalytic metal element M in the activation catalyst region 41. It is reduced to a simple substance of a conductive metal, thereby forming a conductive line 20 including a simple substance of a conductive metal and a simple substance of a catalytic metal dispersed between the elemental particles of the conductive metal.

It can be understood that the sequence of the step S4 and the step S5 can also be reversed, that is, the substrate on which the activation catalyst region 41 is formed is first electrolessly plated with a conductive metal to convert the activation catalyst region 41 into the conductive line 20, and then moved. Except for the unactivated catalyst zone 42. It is preferable to remove the unactivated catalyst region 41 after electroless plating to form the conductive line 20.

The above solution containing conductive metal ions may be a copper sulfate solution or a copper nitrate solution. An electroless plating conductive metal solution having a conductive metal ion which is conventionally used in electroless plating such as a copper chloride solution, a nickel sulfate solution, a nickel nitrate solution, a nickel chloride solution, or a silver nitrate solution.

Referring to FIG. 7, an electronic device 400 can be a mobile phone, a computer, an e-reader, a smart watch, or the like. The electronic device 400 includes a housing 401 and a screen 402 mounted on the housing 401. The housing 401 cooperates with the screen 402 to form an accommodating space (not shown). The electronic device 400 further includes a housing. A space board (not shown) is provided, which includes the above-described circuit substrate 100.

The circuit board 100 is fabricated by chemically reacting PI-COOH on the surface of the substrate 10 with the unactivated catalytic metal ion Mn ⁺ to obtain [PI-COO] _n M, [PI-COO] _n M and PI-COO- The bonded unactivated catalytic metal ions Mn ^{+ are} photoreduced to a simple substance M and embedded on the surface of the substrate 10, so that the formed conductive lines 20 have a good bonding force with the substrate 10. The manufacturing method of the circuit substrate 100 does not need to use the dry film photoresist layer in the usual subtractive process, thereby facilitating the generation of the side etching phenomenon, the process is simple, and resources are saved.

100‧‧‧ circuit board

10‧‧‧Substrate

11‧‧‧ Carrier Board

12‧‧‧ Cover film

20‧‧‧Electrical circuit

Claims (10)

A method of fabricating a circuit substrate, comprising the steps of: providing a substrate comprising at least a surface of a polyimine having -COOH; forming an unactivated catalytic metal ion and photoinitiating on the surface of the substrate The unactivated catalyst layer of the agent, chemically reacts the unactivated catalytic metal ions near the substrate with the polyethylenimine having -COOH on the surface of the substrate; the portion of the unactivated catalyst layer The area is exposed, so that the unactivated catalytic metal ions in the region are activated by the photoinitiator to form a catalytic metal element, and the unactivated catalytic metal ions after the bonding are also activated by the photoinitiator. The catalytic metal element is embedded in the surface of the substrate, and the exposed region is converted into an activation catalyst region, and the unexposed region is an unactivated catalyst region; and the activation catalyst region is formed The substrate is electrolessly plated with a conductive metal such that the conductive metal ions enter the activation catalyst region and are reduced to a conductive metal element under the catalysis of the catalytic metal element, thereby causing the activation catalyst region to rotate. A conductive line comprising a conductive metal element and a catalytic metal element dispersed between the elemental particles of the conductive metal, and removing the unactivated layer before the electroless plating of the conductive metal to form the conductive line or after the electroless plating of the conductive metal to form the conductive line Catalyst zone. The method of manufacturing the circuit board according to the first aspect of the invention, wherein the substrate comprises a carrier and a cover film bonded to at least one surface of the carrier, the cover film comprising a polyimine having -COOH; Or the substrate is a polyimide substrate, and the polyimide substrate comprises a polyimine having -COOH. The method for fabricating a circuit substrate according to claim 1, wherein the conductive metal element is selected from one or more of copper, nickel, and silver; and the catalytic metal element is selected from the group consisting of palladium metal. One or more of elemental, gold metal elemental, nickel metal elemental, and cobalt metal elemental. The method for fabricating a circuit board according to claim 1, wherein the solution containing the conductive metal ions is selected from the group consisting of copper sulfate solution, copper nitrate solution, copper chloride solution, nickel sulfate solution, nickel nitrate solution, and chlorine. One or more of a nickel solution or a silver nitrate solution. The circuit board is manufactured by the method for manufacturing a circuit board according to any one of claims 1 to 4, wherein the circuit substrate comprises a substrate and a conductive layer bonded to at least one surface of the substrate a circuit comprising at least a surface of the substrate a polyimine having -COOH, wherein the conductive line contains a simple substance of a conductive metal and a catalytic metal element dispersed between the elemental particles of the conductive metal, and a part of the conductive line touches The dielectric metal element is embedded in a surface of the substrate that is in contact with the conductive line. The circuit substrate of claim 5, wherein the conductive metal element is selected from one or more of copper, nickel, and silver; and the catalytic metal element is selected from the group consisting of palladium metal elemental substance and gold metal elemental substance. One or more of a single element of nickel metal and a simple substance of cobalt metal. The circuit substrate of claim 5, wherein the substrate comprises a carrier and a cover film bonded to at least one surface of the carrier, each conductive line being bonded to the surface of the cover film away from the carrier. The cover film contains a polyimine having -COOH. The circuit substrate according to claim 5, wherein the substrate is a polyimide substrate, and the polyimide substrate comprises a polyimine having -COOH. A circuit board comprising the circuit board produced by the method of manufacturing the circuit board according to any one of claims 1 to 4, wherein the circuit board is improved. An electronic device comprising at least one circuit board, the circuit board comprising the circuit board produced by the method of manufacturing the circuit board according to any one of claims 1 to 4.