TWI608765B - Print circuit board and method for manufacturing same - Google Patents

Description

Circuit board and manufacturing method thereof

The present invention relates to the field of circuit boards, and in particular, to a circuit board and a method of fabricating the same.

With the trend of thinner and lighter electronic products, the choice of bottom copper materials will become more and more light and thin, and the processing of blind holes on thin and light copper is indispensable in the process of circuit board production. However, the surface treatment in the current blind hole processing process will cause a reduction in copper thickness, and in each of the previous processes, the surface treatment is involved many times, and multiple copper thickness reductions are superimposed, and the risk of blind hole breakage may occur, thereby affecting Line formation and conduction of lines at each layer.

In view of this, the present invention provides a circuit board capable of reducing the risk of hole breakage. .

A circuit board comprising a substrate layer, a first conductive circuit layer and a second conductive circuit layer formed on opposite surfaces of the substrate layer, at least one conductive blind hole and at least one reinforcing pad; The at least one conductive via is electrically connected to the first conductive circuit layer and the second conductive circuit layer, and the second conductive circuit layer is formed with a recess corresponding to the conductive blind hole, and at least one of the reinforcing pads is formed in the second The conductive circuit layer is away from the surface of the substrate layer so as to protrude from the second conductive circuit layer, and one of the reinforcing pads is formed at a bottom of the conductive blind hole.

A method of manufacturing a circuit board, the method comprising: providing a circuit substrate, the circuit substrate comprising a substrate layer and a first copper foil layer and a second copper foil formed on opposite surfaces of the substrate layer a layer; a predetermined position on a surface of the second copper foil layer away from the substrate layer forming at least one reinforcing pad protruding from the second copper foil layer; forming the reinforcing pad from the first copper foil layer At least one conductive blind hole, the second copper foil layer is formed with a recess corresponding to the portion of the conductive blind hole; forming the first copper foil layer and the second copper foil layer to form the first conductive circuit layer and the second conductive circuit layer The conductive via hole electrically connects the first conductive circuit layer and the second conductive circuit layer.

The circuit board provided by the invention forms at least one reinforcing pad on the second copper foil layer corresponding to the conductive blind hole, increases the thickness of the bottom copper of the conductive blind hole, and reduces the processing of the conductive blind hole in the blind hole and the subsequent process There is a risk of hole breakage.

100‧‧‧ boards

10‧‧‧ circuit board

11‧‧‧Substrate layer

12‧‧‧First copper foil layer

13‧‧‧Second copper foil layer

131‧‧‧ dent

14‧‧‧First dry film

15‧‧‧Second dry film

151‧‧‧ first opening

152‧‧‧Enhanced mat

16‧‧‧ Brown film

17‧‧‧ Conductive blind holes

171‧‧‧Blind hole

172‧‧‧ Conductive layer

173‧‧‧Electroplating

18‧‧‧First conductive circuit layer

19‧‧‧Second conductive circuit layer

21‧‧‧First cover layer

22‧‧‧second cover layer

23‧‧‧ solder mask

200‧‧‧Circuit board intermediates

1 is a cross-sectional view of a circuit substrate provided by the present invention.

Fig. 2 is a cross-sectional view showing a dry film formed on opposite sides of the circuit board of Fig. 1;

Figure 3 is a cross-sectional view of the dry film of Figure 2 after forming a first opening.

4 is a cross-sectional view of the first opening illustrated in FIG. 3 after selective plating to form a reinforcing pad.

Figure 5 is a cross-sectional view of the dry film removed after Figure 4 is removed.

Fig. 6 is a cross-sectional view showing the surface of the copper foil layer shown in Fig. 5 formed into a brown/blackened film.

Fig. 7 is a cross-sectional view showing a blind hole formed in the circuit board shown in Fig. 6.

Figure 8 is a cross-sectional view of the brown/blackened film described in Figure 7 after removal.

Fig. 9 is a cross-sectional view showing a conductive layer formed on the wall of the blind hole shown in Fig. 8.

Fig. 10 is a cross-sectional view showing the blind hole of Fig. 9 electroplated to form a conductive blind hole.

Fig. 11 is a cross-sectional view showing the formation of a conductive wiring layer in the copper foil layer shown in Fig. 10.

Figure 12 is a cross-sectional view showing the thickness of a cover film formed on the conductive wiring layer described in Figure 11.

Fig. 13 is a cross-sectional view showing a gap-preventing layer formed in the gap of the cover film layer shown in Fig. 12, and further forming a circuit board.

The circuit board provided in the present application and the manufacturing method thereof will be further described below with reference to FIGS. 1 to 13 and the embodiments.

A manufacturing method of a circuit board 100 includes the following steps: First, referring to FIG. 1, a circuit substrate 10 is provided.

The circuit substrate 10 includes an insulating substrate layer 11, a first copper foil layer 12 and a second copper foil layer 13. The first copper foil layer 12 and the second copper foil layer 13 are respectively formed on the substrate. The opposite sides of the layer 11 are.

The material of the substrate layer 11 may be polyimide (PI), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN). The flexible material may be a rigid support material such as a resin plate, a ceramic plate or a metal plate.

In the second step, referring to FIG. 2 to FIG. 5, at least one reinforcing pad 152 is formed at a predetermined position on the surface of the second copper foil layer 13 of the circuit substrate 10 away from the substrate layer, thereby forming a circuit board intermediate. 200.

First, referring to FIG. 2, a first dry film layer 14 and a second dry film layer 15 are formed on the surface of the first copper foil layer 12 and the second copper foil layer 13 away from the substrate layer 11, respectively. . The first dry film layer 14 and the second dry film layer 15 may be pressed on both sides of the first copper foil layer 12 and the second copper foil layer 13 by a lamination device. Next, referring to FIG. 3, the first dry film layer 14 and the second dry film layer 15 are selectively hardened by an exposure process, and then the dry film of the non-hardened zone is dissolved by a developing process to form at least one An opening 151. The width of the first opening 151 is defined as D1. In the present embodiment, D1 is approximately 100-150 um.

Again, referring to FIG. 4, at least one of the reinforcing pads 152 is formed in at least one of the first openings 151 by selective plating. The reinforcing pad 152 may have a circular shape or a square shape or other shapes.

Thereafter, referring to FIG. 5, the hardened dry film is removed by a film removing device, and at least one of the reinforcing pads 152 protrudes from the second copper foil layer 13 to form the circuit board intermediate body 200.

The circuit board intermediate body 200 includes the base material layer 11, the first copper foil layer 12, the second copper foil layer 13, and at least one reinforcing pad 152 formed on the second copper foil layer 13.

The width of the reinforcing pad 152 is equal to the width of the first opening 151, and the thickness of the reinforcing pad 152 is defined as D2, and the thickness of D2 is not more than one-half of the thickness of the second copper foil layer. The position at which the reinforcing pad 152 is formed corresponds to the position of the subsequently formed conductive blind hole 17.

In the third step, referring to FIG. 6 to FIG. 10, at least one conductive blind hole 17 is formed on the circuit board intermediate body 200 formed in the second step. The reinforcing pad 152 is disposed at the bottom of the conductive blind hole 17 , and the size of the reinforcing pad is not less than the size of the bottom of the conductive blind hole 17 .

Specifically, at least one blind hole 171 is formed on the circuit board intermediate body 200 formed in the second step, and at least one of the blind holes 171 may be formed by mechanical drilling or laser drilling. In the present embodiment, at least one of the blind holes 171 is formed by laser drilling. In this embodiment, the step of fabricating at least one of the conductive vias 17 is as follows: First, referring to FIG. 6, the first copper foil layer 12, the second copper foil layer 13, and the reinforcing pad 152 are passed through a browning process. The surface forms a browning film 16. The browning film 16 serves to reduce the loss of laser ablation energy.

In other embodiments, a blackening film may be formed on the surface of the first copper foil layer 12, the second copper foil layer 13, and the reinforcing pad 152 by a blackening process.

Among them, before the brown/blackening is performed, the circuit board intermediate body 200 formed in the second step needs to be surface-treated.

Next, referring to FIG. 7, at least one blind hole 171 is formed by laser ablation from the surface of the first copper foil layer 12 to the second copper foil layer 13, and the blind hole 171 penetrates the first copper foil layer 12 and the The base layer 11 has a blind hole 171 opposite to the position of the reinforcing pad 152. A portion of the second copper foil layer 13 (ie, the second copper foil layer 13 at the bottom of the blind hole 171) corresponding to the blind hole 171 is defined as a bottom copper of the blind hole 171, and the reinforcing pad 152 makes the blind hole 171 The thickness of the bottom copper is increased. In this embodiment, as shown in FIG. 7, the circuit board intermediate body 200 with the blind hole 171 partially ablates the second copper foil layer 13 when the laser ablation forms the blind hole 171, and performs the surface. During processing, a portion of the second copper foil layer 13 is also etched such that a surface of the second copper foil layer 13 forms a plurality of recesses 131, and the recess 131 reduces the thickness of the bottom copper of the blind via 171. Hole breakage is likely to occur in the subsequent process. However, in the present invention, since the thickness of the bottom copper of the blind hole 171 is increased, the bottom copper of the blind hole 171 is not easily removed in the subsequent process after laser ablation and surface treatment. The hole broke.

Again, referring to Figure 8, the browning film 16 is removed by microetching.

Then, referring to FIG. 9, the blind via 171 is subjected to a hole metallization process, and a conductive layer 172 that turns on the first copper foil layer 12 and the second copper foil layer 13 is formed on the sidewall of each of the blind vias 171. .

The metallization of the blind via 171 can be achieved by a process such as black shadow or copper.

Before the hole hole 171 is subjected to the hole metallization treatment, surface pretreatment such as brushing, high pressure, ultrasonic water washing, plasma plasma removal, microetching, activation, etc. are required to form the above-mentioned The surface of the circuit board intermediate body 200 of the blind hole 171 and the inner wall of the blind hole 171 are ground, cleaned, glued, and the like. The above processes also reduce the copper thickness of the bottom copper of the blind via 171. However, in the present invention, since the thickness of the bottom copper of the blind via 171 is increased, the blind via 171 is not easily made in the above process. The hole broke.

Finally, referring to FIG. 10, a plating layer 173 is formed on the conductive layer 172 of the blind via 171 by selective plating, thereby forming a conductive via hole 17.

In the fourth step, referring to FIG. 11, the first copper foil layer 12 and the second copper foil layer 13 are respectively formed into a first conductive wiring layer 18 and a second conductive wiring layer 19.

The first conductive circuit layer 18 and the second conductive circuit layer 19 can be formed by an image transfer process and an etching process.

In the fifth step, referring to FIG. 12, a first cover film layer 21 is formed on the surface of the first conductive circuit layer 18, and a second cover film layer 22 is formed on the surface of the second conductive circuit layer 19.

The first cover film layer 21 includes at least one second opening 211 , and a portion of the first conductive circuit layer 18 is exposed from the second opening 211 .

Before forming the first cover film layer 21 and the second cover film layer 22, the circuit board surface pre-treatment of the circuit board formed in the fourth step is also required, in the process, the bottom copper of the conductive blind hole 17 is The copper thickness is also reduced. However, in the present invention, since the reinforcing pad 152 is added at a position corresponding to the bottom copper of the conductive blind hole 17, the bottom copper of the conductive blind hole 17 is thickened. Hole breakage is less likely to occur in the above process.

In the sixth step, referring to FIG. 13, a solder resist layer 23 is formed in the second opening 211 to form the circuit board 100.

In the embodiment, the circuit board 100 is a double-layer board. In other embodiments, the circuit board 100 is not limited to a double-layer board, and may also be a multi-layer board.

Specifically, referring to FIG. 13 , the circuit board 100 includes a substrate layer 11 , a first conductive circuit layer 18 and a second conductive circuit layer 19 formed on opposite surfaces of the substrate layer 11 . a first cover film layer 21 and a solder resist layer 23 on the surface of the first conductive circuit layer 18 away from the substrate layer 11 and a distance away from the second conductive circuit layer 19 and the reinforcing pad 152 A second cover film layer 22 on the surface of the substrate layer 11.

The circuit board 100 is formed with at least one conductive blind hole 17 electrically connected to the first conductive circuit layer 18 and the second conductive circuit layer 19. A portion of the second copper foil layer 13 corresponding to the conductive blind hole 17 is formed with a plurality of recesses 131, and the recess 131 causes the bottom copper of the conductive blind via 17 to be reduced. At least one of the reinforcing pads 152 is formed on a surface of the second conductive wiring layer 19 remote from the substrate layer 11, and each of the reinforcing pads 152 is opposed to a position of each of the conductive blind holes 17. The thickness of the reinforcing pad 152 is defined as D2, and the thickness of D2 is not more than one-half of the thickness of the second copper foil layer. At least one second opening is formed on the first cover film layer 21, and the solder resist layer 23 is selectively distributed in the second opening 211 of the first cover film layer 21.

The circuit board 100 and the manufacturing method thereof provide at least one reinforcing pad 152 having a certain thickness at a position corresponding to the second copper foil layer 13 of the at least one conductive blind hole 17 to increase the corresponding to the reinforcing pad 152. The thickness of the bottom copper of the conductive blind via 17 can prevent the bottom of the conductive blind via 17 from being broken after each process and each pre-treatment process, so as to meet the design requirements of the conductive blind via and the circuit.

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.

100‧‧‧ boards

11‧‧‧Substrate layer

131‧‧‧ dent

152‧‧‧Enhanced mat

17‧‧‧ Conductive blind holes

18‧‧‧First conductive circuit layer

19‧‧‧Second conductive circuit layer

21‧‧‧First cover layer

22‧‧‧second cover layer

23‧‧‧ solder mask

Claims (3)

A circuit board manufacturing method, the method comprising: providing a circuit substrate, the circuit substrate comprising a substrate layer and a first copper foil layer and a second copper foil layer formed on opposite surfaces of the substrate layer; Forming at least one reinforcing pad at a predetermined position on a surface of the second copper foil layer away from the substrate layer, the reinforcing pad protruding from the second copper foil layer; forming at least one from the first copper foil layer toward the reinforcing pad a conductive blind hole, the portion of the second copper foil layer corresponding to the conductive blind hole is formed with a recess; the first copper foil layer and the second copper foil layer are formed to form a first conductive circuit layer and a second conductive circuit layer, The conductive blind via electrically connects the first conductive wiring layer and the second conductive wiring layer. The method of manufacturing the circuit board of claim 1, wherein the size of the reinforcing pad is not less than the size of the bottom of the conductive blind hole. The method of manufacturing the circuit board of claim 1, wherein the thickness of the reinforcing pad is not more than one-half of the thickness of the second copper foil layer.