TWI484875B - Circuit board and method for manufacturing same - Google Patents

Description

Circuit board and circuit board manufacturing method

The present invention relates to a circuit board manufacturing technology, and in particular, to a circuit board and a circuit board manufacturing method.

Due to the thin and light requirements of the flexible circuit board, when the internal circuit is used as the signal line for external signal transmission, it is usually required to cover the outer layer of the flexible circuit board with an EMI shielding film to prevent signal loss caused by external electromagnetic interference. .

The conductive silver foil is usually a four-layer structure, that is, a protective film, a metal film, an anisotropic conductive paste, and a release film in this order. Before the bonding, the release film needs to be removed, thereby bonding the anisotropic conductive paste and the flexible circuit board. However, since the conductive effect of the anisotropic conductive paste is inferior to that of the metal, the resistance changes when the transition from the anisotropic conductive paste to the metal film, so that the effect of the return is poor when the signal is returned. In addition, the thickness of the anisotropic conductive paste is thick, and the thickness of the flexible circuit board having a thick anisotropic conductive paste is also thick, and it is difficult to meet the requirements of lightness and thinness.

In view of this, it is necessary to provide a circuit board and a circuit board manufacturing method, which can realize electromagnetic shielding effect on a signal line without using an anisotropic conductive adhesive.

A circuit board comprising a circuit substrate arranged in sequence, an ink layer containing a metal element, and an electromagnetic mask structure. The circuit substrate includes an outer conductive layer that is in contact with each other and The first insulating layer. The outer conductive layer is formed on one side of the first insulating layer. The outer conductive circuit layer includes a ground line. An opening is formed in the first insulating layer to expose the ground line. The metal element-containing ink layer is formed on a surface of the first insulating layer away from the outer conductive layer and a ground line exposed from the opening. The grounding line is electrically connected to the electromagnetic shielding structure through a metal element in the metal layer containing ink.

A circuit board manufacturing method includes the steps of: providing a circuit substrate, wherein the circuit substrate comprises an outer conductive circuit layer and a first insulating layer that are in contact with each other, and the outer conductive circuit layer comprises a signal line and a grounding line surrounding the signal line, Forming a plurality of openings in the first insulating layer, the ground line is exposed from the opening; forming a metal ion-containing ink on a surface and an opening of the first insulating layer; and reducing the metal containing a metal ion in the ionic ink to form an ink layer containing a metal element; and an electromagnetic mask structure formed on a surface of the metal element-containing ink layer, the material of the electromagnetic mask structure being copper, the ground line passing The metal element in the metal element-containing ink layer and the electromagnetic mask structure are electrically connected to each other.

The circuit board and the circuit board manufacturing method provided by the technical solution form a metal ion-containing ink on the surface of the insulating layer by printing, and reduce metal ions in the metal ion-containing ink to form an ink layer containing a metal element, and then pass through Electroless copper plating and copper plating form an electromagnetic mask structure. The electromagnetic shielding structure can act as an electromagnetic shielding on the signal line, thereby preventing electromagnetic interference generated by the outside on the signal line. Compared with the prior art, the use of the anisotropic conductive adhesive to form the electromagnetic mask layer can effectively shorten the process of circuit board fabrication, reduce the manufacturing cost of the circuit board, and improve the yield of the circuit board.

110‧‧‧ circuit board

111‧‧‧First insulation

112‧‧‧Outer conductive circuit layer

113‧‧‧Second insulation

114‧‧‧Inner conductive circuit layer

115‧‧‧ basal layer

110a‧‧‧Electromagnetic mask forming zone

110b‧‧‧General area

Opening 1111‧‧

1121‧‧‧Signal lines

1122‧‧‧ Grounding circuit

1141‧‧‧First line

1142‧‧‧second line

120‧‧‧Ink containing metal ions

130‧‧‧Ink layer containing metal element

140‧‧‧Electromagnetic mask structure

141‧‧‧Electrochemical copper plating

142‧‧‧Electroplated copper layer

150‧‧‧ solder mask

100‧‧‧ boards

1 is a top plan view of a circuit substrate provided by an embodiment of the present technical solution.

2 is a cross-sectional view of the circuit board of FIG. 1 taken along line II-II.

Figure 3 is a cross-sectional view showing the formation of a metal ion-containing ink on the first insulating layer of Figure 2.

Fig. 4 is a cross-sectional view showing an ink layer containing a metal element obtained by reducing metal particles in the metal ion-containing ink of Fig. 3 into a simple substance of a metal.

Fig. 5 is a cross-sectional view showing the formation of an electroless copper plating layer of the metal-containing ink layer of Fig. 4.

Figure 6 is a cross-sectional view showing the formation of an electroplated copper layer on the electroless copper plating layer of Figure 5.

Figure 7 is a cross-sectional view of the circuit board obtained after forming a solder resist layer on the electroplated copper layer of Figure 6.

Figure 8 is a top plan view of the circuit board of Figure 7.

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

The circuit board manufacturing method provided by the embodiment of the technical solution includes the following steps:

In the first step, referring to Figures 1 and 2, a circuit substrate 110 is provided.

In the present embodiment, the circuit substrate 110 is a circuit board on which a conductive line is formed. The circuit substrate 110 includes a first insulating layer 111, an outer conductive wiring layer 112, a second insulating layer 113, an inner conductive wiring layer 114, and a base layer 115 which are disposed in this order from top to bottom. The circuit substrate 110 has at least one electromagnetic mask forming region 110a and a shape other than the electromagnetic mask The normal area 110b outside the area 110a is used to form an electromagnetic electromagnetic mask structure. For the sake of understanding, in the present embodiment, the circuit substrate 110 has an electromagnetic mask forming region 110a as an example for description. In other embodiments, the number of the electromagnetic mask forming regions 110a may be two, three or more.

A plurality of openings 1111 are formed in the first insulating layer 111 in the electromagnetic mask forming region 110a such that a portion of the outer conductive layer 112 is exposed from the plurality of openings 1111.

The outer conductive layer 112 is located on one side of the first insulating layer 111, and the outer conductive layer 112 in the electromagnetic mask forming region 110a includes a signal line 1121 and a ground line 1122. The ground line 1122 surrounds the signal line 1121, and the ground line 1122 is exposed from the plurality of openings 1111.

The second insulating layer 113 is located on a side of the outer conductive layer 112 away from the first insulating layer 111.

The inner conductive circuit layer 114 is located on a side of the second insulating layer 113 away from the outer conductive layer 112. That is, the second insulating layer 113 is located between the outer conductive layer 112 and the inner conductive layer 114. The inner conductive circuit layer 114 includes a first line 1141 and a second line 1142. The first line 1141 is located in the electromagnetic mask forming area 110a, and may be a signal line or a ground line. The second line 1142 is located in the normal area 110b. In this embodiment, the first line 1141 is a signal line, and is electrically connected to the signal line 1121 through a conductive hole (not shown) in the second insulating layer 113.

The base layer 115 is located on a side of the inner conductive layer 114 away from the second insulating layer 113 for carrying the first insulating layer 111, the outer conductive layer 112, the second insulating layer 113, and the inner conductive line. Layer 114. The base layer 115 base layer 115 can It may be a flexible resin layer such as Polyimide (PI), Polyethylene Terephthalate (PET) or Polythylene Naphthalate (PEN). A multilayer substrate comprising a plurality of alternating layers of resin layers and a plurality of layers of conductive wiring layers. That is, the circuit substrate 110 may be a flexible circuit board having a conductive circuit layer larger than two layers.

In this step, the outer conductive circuit layer 112 and the inner conductive circuit layer 114 can be formed by using a method for manufacturing conductive lines in the prior art. The opening 1111 can be formed by laser ablation.

In the process of forming the opening 1111, a portion of the material of the original opening portion remains in the opening 1111 or is adsorbed to the inner wall of the opening 1111 to form a slag. After forming the opening 1111, the method further includes performing desmear treatment on the circuit substrate 110. That is, the circuit substrate 110 is processed by plasma so that the slag in the opening 1111 is removed.

In the second step, referring to FIG. 3, a metal ion-containing ink 120 is formed in the surface of the first insulating layer 111 and the opening 1111 in the electromagnetic mask forming region 110a by a printing method. The metal ion-containing ink 120 may be an ink containing metal ions such as palladium particles, silver particles, and gold particles. In this embodiment, the metal ion-containing ink 120 is an ink containing palladium particles.

In the third step, referring to FIG. 4, the metal ions in the metal ion-containing ink 120 are reduced to change the metal ion-containing ink 120 into a metal-containing ink layer 130. The metal-containing elementary ink layer 130 has a thickness ranging from 3 micrometers to 5 micrometers. In this embodiment, the metal element-containing ink layer 130 is a palladium-containing ink layer having a thickness of 4 μm.

In the fourth step, referring to FIG. 5 and FIG. 6, a layer of electromagnetic shielding structure 140 is formed on the surface of the metal-containing ink layer 130. The electromagnetic shielding structure 140 is electrically connected to the grounding line 1122 in the outer conductive layer 112 by the metal element in the metal-containing ink layer 130. In this embodiment, the material of the electromagnetic shielding structure 140 is copper, and the electromagnetic shielding structure 140 can be formed by the following steps: First, the surface of the metal-containing ink layer 130 is electrolessly plated by copper. A layer of electroless copper plating 141 is formed.

Then, a layer of electroplated copper 142 is formed on the surface of the electroless copper plating layer 141 by electroplating. The electroless copper plating layer 141 and the electroplated copper layer 142 together constitute the electromagnetic shielding structure 140.

In the fourth step, referring to FIG. 7 and FIG. 8 , a solder resist layer 150 is formed on the surface of the electromagnetic mask structure 140 to obtain the circuit board 100 .

The solder resist layer 150 can be formed by printing ink. The solder resist layer 150 has a thickness of less than 10 microns.

Referring to FIG. 7 , the technical solution further provides a circuit board 100 formed by the above method. The circuit board 100 includes a circuit board 110 , a metal element-containing ink layer 130 , an electromagnetic mask structure 140 , and solder resist . Layer 150.

The circuit substrate 110 includes a first insulating layer 111, an outer conductive wiring layer 112, a second insulating layer 113, an inner conductive wiring layer 114, and a base layer 115 which are disposed in this order from top to bottom. A plurality of openings 1111 are formed in the first insulating layer 111 such that a portion of the outer conductive layer 112 is exposed from the plurality of openings 1111. The outer conductive circuit layer 112 is located at one side of the first insulating layer 111 and includes a signal line 1121 and a ground line 1122. The ground line 1122 surrounds the signal line 1121, and the ground line 1122 is from the A plurality of openings 1111 are exposed. The second insulating layer 113 is located on a side of the outer conductive layer 112 away from the first insulating layer 111.

The metal element-containing ink layer 130 is formed on a surface of the first insulating layer 111 away from the outer conductive layer 112 and a surface of the ground line 1122 exposed from the opening 1111, and has a thickness of 3 micrometers. Up to 5 microns. The grounding line 1122 is electrically conducted through the metal element in the metal-containing ink layer 130 and the electromagnetic shielding structure 140. The material of the electromagnetic shielding structure 140 is copper, and the thickness of the electromagnetic shielding structure 140 is less than or equal to 15 micrometers. The solder resist layer 150 has a thickness greater than 10 microns. The area of the electromagnetic shielding structure 140 is larger than the area where the signal line 1121 is distributed, and is electrically connected to the ground line 1122 so as to function as an electromagnetic shielding for the signal line 1121.

It can be understood that the first line 1141 of the inner conductive layer 114 can also be a ground line, and the first line 1141 passes through the conductive hole and the outer conductive layer 112 in the second insulating layer 113. The grounding lines 1122 are electrically connected. In this case, the signal lines 1121 are located between the electromagnetic shielding structure 140 and the inner conductive wiring layer 114. The area of the electromagnetic shielding structure 140 and the first line 1141 is larger than the area where the signal line 1121 is distributed, and both are electrically connected to the ground line 1122, so that the electromagnetic shielding effect on the signal line 1121 can be performed.

The circuit board provided by the technical solution and the manufacturing method thereof, the metal ion-containing ink is formed on the surface of the insulating layer by printing, and the metal ions in the metal ion-containing ink are reduced to form an ink layer containing the metal element, and then pass the chemistry The electromagnetic shielding structure is formed by copper plating and copper plating. The electromagnetic shielding structure can act as an electromagnetic shielding on the signal line, thereby preventing electromagnetic interference generated by the outside on the signal line. Compared with the prior art, the use of an anisotropic conductive adhesive to form an electromagnetic mask layer can have Effectively shorten the process of board fabrication, reduce board manufacturing costs, and increase board yield. Further, the metal layer-containing ink layer has a thickness ranging from 3 μm to 5 μm, which is smaller than the thickness of the anisotropic conductive paste, and can reduce the thickness of the circuit board.

It will be understood by those of ordinary skill in the art that after forming the ink layer 130 containing the metal element, an opening may be formed in the ink layer 130 containing the metal element to expose the ground line 1122 and then form an electromagnetic mask. In the structure, the electromagnetic mask structure fills the openings in the ink layer 130 containing the metal element, so that the electromagnetic shielding structure is directly electrically connected to the ground line 1122.

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.

110‧‧‧ circuit board

111‧‧‧First insulation

112‧‧‧Outer conductive circuit layer

113‧‧‧Second insulation

114‧‧‧Inner conductive circuit layer

115‧‧‧ basal layer

1121‧‧‧Signal lines

1122‧‧‧ Grounding circuit

130‧‧‧Ink layer containing metal element

140‧‧‧Electromagnetic mask structure

150‧‧‧ solder mask

100‧‧‧ boards

Claims (9)

A circuit board comprising a circuit substrate arranged in sequence, an ink layer containing a metal element, and an electromagnetic mask structure, the circuit substrate comprising an outer conductive layer and a first insulating layer in contact with each other, wherein the outer conductive layer is formed on One side of the first insulating layer, the outer conductive layer includes a grounding line, and an opening is formed in the first insulating layer to expose the grounding line, and the metal-containing ink layer is formed in the first insulating layer a first insulating layer away from a surface of the outer conductive layer and a surface of a ground line exposed from the opening, the ground line passing through the metal element in the metal layer-containing ink layer and the electromagnetic mask structure Electrically conductive, wherein the metal element is palladium. The circuit board of claim 1, wherein the circuit substrate further comprises a second insulating layer and an inner conductive circuit layer, the outer conductive layer is formed on the second insulating layer and the first insulating layer Between the layers. The circuit board of claim 1, wherein the metal-containing element has an ink layer thickness ranging from 3 micrometers to 5 micrometers, and the electromagnetic mask structure has a thickness of less than or equal to 15 micrometers. The circuit board of claim 1, wherein the circuit board further comprises a solder resist layer formed on a surface of the electromagnetic mask structure, the solder resist layer having a thickness of less than 10 micrometers. A circuit board manufacturing method includes the steps of: providing a circuit substrate, wherein the circuit substrate comprises an outer conductive circuit layer and a first insulating layer that are in contact with each other, and the outer conductive circuit layer comprises a signal line and a grounding line surrounding the signal line, Forming a plurality of openings in the first insulating layer, the ground line is exposed from the opening; forming a metal ion-containing ink on a surface and an opening of the first insulating layer; Reducing metal ions in the metal ion-containing ink to form an ink layer containing a metal element; and forming an electromagnetic mask structure on the surface of the metal element-containing ink layer, the ground line passing through the metal-containing element The metal element in the ink layer and the electromagnetic mask structure are electrically connected to each other. The method for fabricating a circuit board according to claim 5, wherein the method for forming the electromagnetic mask structure comprises the steps of: forming an electroless copper plating on the surface of the metal element-containing ink layer by electroless copper plating. And forming an electroplated copper layer on the surface of the electroless copper plating layer by an electroplating method, the electroless copper plating layer and the electroplated copper layer collectively constituting the electromagnetic shielding structure. The method of fabricating a circuit board according to claim 5, wherein the metal layer-containing ink layer has a thickness ranging from 3 micrometers to 5 micrometers, and the electromagnetic mask structure has a thickness of less than or equal to 15 micrometers. The circuit board manufacturing method of claim 5, wherein the circuit board further comprises a solder resist layer formed on a surface of the electromagnetic mask structure, the solder resist layer having a thickness of less than 10 Micron. The method for fabricating a circuit board according to claim 5, wherein the metal element is palladium.