TW201733422A - Multi-layer printed circuit board without solder pad and manufacturing method thereof capable of eliminating the defective hole-filling problem by using image transfer to form a via hole and filling up the hole to form a conductive post - Google Patents

Abstract

The present invention provides a multi-layer printed circuit board without solder pad and a manufacturing method thereof. The manufacturing method of a multi-layer printed circuit board without solder pad includes arranging a first layer of circuit on a substrate; using an image-transfer to provide a photoresist layer for forming at least one via hole to connect the first layer of circuit and the second layer of circuit; electroplating the at least one via hole to form at least one conductive post, and then arranging a second layer of base material; and arranging the second layer of circuit on the second layer of base material, whereby the second layer of circuit is connected to the first layer of circuit through directly connecting the second layer of circuit and the conductive post so as to complete the manufacture of the multi-layer printed circuit board without solder pad. With the arrangement of the conductive post, there is no need to fill up the depth of the via hole when the second layer of circuit is formed, so that the second layer of circuit can be flatter. Furthermore, by means of directly using image transfer to form the at least one via hole and filling up the hole to form the at least one conductive post, it is able to eliminate the defective hole-filling problem caused by misalignment between the image-transferred photoresist layer and the laser-penetrated via hole.

Description

Solder padless multilayer circuit board and manufacturing method thereof

The invention relates to a solderless pad multilayer circuit board and a manufacturing method thereof, in particular to a solderless pad multilayer circuit board capable of filling a blind hole and having the same height throughout the second layer line and a manufacturing method thereof.

The existing solderless pad multilayer circuit board has a plurality of circuit layers, and each circuit layer is separately formed in sequence, and at least one blind hole formed by laser perforation may be formed between two adjacent circuit layers, so that two adjacent circuit layers are The line can be electrically connected by the blind hole.

Referring to FIG. 6 and FIG. 7 , the conventional solderless multilayer circuit board is manufactured by the following steps: As shown in FIG. 6( a ), a substrate 40 is prepared, and a surface of the substrate 40 is provided with a first plating layer. 41 and a first photoresist layer 42, wherein the first plating layer 41 is disposed between the first photoresist layer 42 and the surface of the substrate 40; as shown in FIG. 6(b), the image shifts the first photoresist a layer 42 is formed by patterning the first photoresist layer 42 to form a first layer wiring pattern; as shown in FIG. 6(c), the first plating layer 41 is plated so that the first plating layer 41 is not patterned. The first photoresist layer 42 is formed in the region covered by the first photoresist layer 42; as shown in FIG. 6(d), the patterned first photoresist layer 42 is removed; as shown in FIG. 6(e) Etching the region of the first plating layer 41 originally covered by the patterned first photoresist layer 42; as shown in FIG. 6(f), a second layer substrate 50 is disposed on the first layer wiring 43 To cover the first layer line 43; as shown in FIG. 6(g), the second layer substrate 50 is laserly perforated to form at least one blind hole 52 to communicate with the first layer line 43; h) shown in the second A second plating layer 51 is disposed on the surface of the substrate 50; as shown in FIG. 6(i), a second photoresist layer 53 is disposed on the surface of the second plating layer 51 to cover the second plating layer 51; (j), the image is transferred to the second photoresist layer 53 to pattern the second photoresist layer 53 to form a second layer wiring pattern; as shown in FIG. 7(k), the second plating layer is plated. 51, a second layer line 54 is formed in a region where the second plating layer 51 is not patterned by the second photoresist layer 53; as shown in FIG. 7(1), the patterned second is removed. The photoresist layer 53; as shown in FIG. 7(m), etches a region where the second plating layer 51 is originally covered by the patterned second photoresist layer 53.

The manufacturing method of the prior art solderless pad multilayer circuit board is prone to deviation when the second layer line 54 is formed and the image is transferred to the second photoresist layer 53, so that the second layer line pattern fails to accurately correspond. The blind vias 52, as shown in FIG. 7(j), and the padless multilayer circuit board, when the second layer line 54 is formed, the wiring area of the second layer line 54 passes directly above the blind via 52. The top of the blind via 52 is not formed with a pad, and the line width of the second layer 54 is smaller than the inner diameter of the blind via 52. Therefore, when the second photoresist layer 53 fails to be aligned and has an offset after the image transfer, the second layer line 54 to be formed above the blind via 52 is offset, and the offset is The two photoresist layers 53 partially shield the blind vias 52, so that the gaps in the blind vias 52 cannot be completely filled during plating, and thus a gap is formed in the inner periphery of the blind vias 52, resulting in poor filling, such as Figure 8 shows.

In addition, the prior art solderless pad multilayer circuit board is fabricated in the electroplating process, since the blind vias 52 communicate with the first layer line 43 and the first layer line 43 and the second layer line 54 have The height difference is low, and the blind hole 52 needs to be filled at the same time and the second layer line 54 is formed. Therefore, the second layer line 54 has a height difference, as shown in FIG. 7(k), the second layer The line 54 corresponds to the portion of the blind hole 52 which needs to fill the depth of the blind hole 52 first in the electroplating process, so it will be lower, and the rest will be higher because it does not need to fill the depth of the blind hole 52. Referring to FIG. 9 further, when the second layer line 54 needs to be soldered to another circuit board 60, since the solder joints 61 on the other circuit board 60 are located on the same plane, the solder connection process is performed. The upper portion of the second layer line 54 is first in contact with the other circuit board 60, but the lower portion of the second layer line 54 corresponding to the blind holes 52 is not yet in contact, so the other layer is not A circuit board 60 is electrically connected, resulting in poor soldering.

In summary, since the solderless pad multilayer circuit board manufactured by the prior art has the disadvantages of poor hole filling of the blind hole 52 and poor soldering when soldering to another circuit board, the prior art method of manufacturing the solderless pad multilayer circuit board needs further Improvement.

In view of the disadvantages of the prior art solderless pad multilayer circuit board manufacturing method, such as blind hole filling and poor soldering, the present invention provides a solderless multilayer circuit board and a manufacturing method thereof, which fill the blind hole and make the second layer each The same height is used to avoid poor hole filling and soldering. The method for manufacturing the solderless multilayer circuit board comprises the following steps: preparing a substrate, and the surface of the substrate is provided with a first plating layer and a first light a resist layer, wherein the first plating layer is disposed between the first photoresist layer and the substrate; and the image is transferred to the first photoresist layer to pattern the first photoresist layer to form a first layer trace pattern; Plating the first plating layer to form a first layer line in a region where the first plating layer is not patterned by the first photoresist layer; removing the patterned first photoresist layer; etching the first An electroplated layer is originally covered by the patterned first photoresist layer; a second photoresist layer is disposed on the first layer of circuitry to encapsulate the first layer of circuitry; and the image is transferred to the second photoresist Layer to form at least one a blind hole is connected to the first layer line; a second plating layer is disposed on the surface of the second photoresist layer; and the first layer line and the second plating layer connected to the at least one blind via are plated to the at least one blind hole Forming at least one via post; disposing a third photoresist layer on the via post and the electroplated second electroplated layer; and transferring the third photoresist layer to at least correspondingly cover the at least one blind via; The plated second plating layer covered by the third photoresist layer after the image transfer; removing the third photoresist layer after the image transfer; removing the second photoresist layer after the image transfer; a second layer of the substrate is disposed on the first layer of the line and the at least one conductive pillar to cover the first layer of the line and the at least one of the conductive pillars; the second layer of the substrate is laserly perforated to expose the at least one conductive pillar a second layer of the substrate surface; a third plating layer is disposed on the surface of the second layer substrate; a fourth photoresist layer is disposed on the surface of the third plating layer; and the fourth photoresist layer is image transferred to be patterned Forming a second layer circuit pattern by the fourth photoresist layer; a third plating layer, forming a second layer line in a region where the third plating layer is not patterned by the fourth photoresist layer; removing the patterned fourth photoresist layer; etching the third plating layer The layer is originally covered by the patterned fourth photoresist layer.

In the present invention, the second photoresist layer is transferred by image to form the at least one blind via, and the at least one via pillar is directly formed by electroplating in the at least one blind via, so that there is no image transfer. The problem that the photoresist layer is not aligned with the blind hole formed by the laser perforation. In addition, the second layer substrate is disposed after the at least one conductive pillar is formed, and the at least one conductive pillar is exposed to the surface of the second layer substrate. When the second layer pattern is electroplated, it is no longer necessary to fill the blind hole depth, and the second layer line formed after electroplating can be made flat. Therefore, in the process of connecting another circuit board with solder, the second layer line can be stably contacted with another circuit board, and there is no unevenness of the surface due to surface unevenness.

In addition, the solderless multilayer circuit board of the present invention comprises: a substrate, a first layer line, at least one conductive pillar, a second layer substrate, and a second layer wiring. The first layer of circuitry is disposed on a surface of the substrate. The at least one conductive pillar is connected to the first layer of the line. The second layer of the substrate is disposed on the surface of the substrate and covers the first layer of the line and covers the at least one conductive pillar. The at least one conductive pillar exposes the surface of the second layer of the substrate, and the area of the at least one conductive pillar exposing the surface of the second layer of the substrate is greater than the contact area of the at least one conductive pillar to the first layer of the wiring. The second layer of circuitry is disposed on the surface of the second layer of the substrate, and the at least one via post is connected to expose a portion of the surface of the second layer of the substrate.

Because the at least one conductive pillar is exposed to be coplanar with the surface of the second substrate and the surface of the second substrate, the second layer is formed to be relatively flat when formed to stably contact another circuit board. welding. And because the conductive pillar exposes the surface of the second layer of the substrate to be larger than the contact area of the at least one via and the first layer, the second layer can be firmly connected to the at least one conductive pillar. Further, the first layer of the circuit is more firmly connected, thereby improving the fabrication yield of the solderless multilayer circuit board.

The technical means adopted by the present invention for achieving the intended purpose are further explained below in conjunction with the drawings and preferred embodiments of the present invention.

Referring to FIG. 1 , the present invention is a method for fabricating a solderless pad multilayer circuit board, comprising the steps of: preparing a substrate (S100); transferring a first photoresist layer (S101); plating a first plating a layer (S102); removing the first photoresist layer (S103); etching the first plating layer (S104); providing a second photoresist layer on the first layer line (S105); image transferring the second light a resist layer to form at least one blind via (S106); a second plating layer disposed on the surface of the second photoresist layer (S107); plating the at least one blind via to form at least one via post (S108); a third photoresist layer (S109); image transferring the third photoresist layer to at least correspondingly cover the at least one blind via (S110); etching the second plating layer (S111); removing the third photoresist layer (S112) Removing the second photoresist layer (S113); providing a second layer substrate (S114); laser perforating the second layer substrate (S115); providing a third plating layer on the second layer substrate a surface (S116); providing a fourth photoresist layer on the surface of the third plating layer (S117); transferring the fourth photoresist layer (S118); plating the third plating layer Line to form a second layer (S119); removing the fourth photoresist layer (S120); etching the third plated layer (S121).

Referring to FIG. 2 to FIG. 4, in FIG. 2(a), a substrate 10 is prepared. The surface of the substrate 10 is provided with a first plating layer 11 and a first photoresist layer 12, wherein the first plating The layer 11 is disposed between the first photoresist layer 12 and the substrate 10; as shown in FIG. 2(b), the image is transferred to the first photoresist layer 12 to form the first photoresist layer 12 to form a a first layer circuit pattern; as shown in FIG. 2(c), the first plating layer 11 is plated to form a first region of the first photoresist layer 11 after the first plating layer 11 is not patterned. a layer line 13; as shown in FIG. 2(d), the patterned first photoresist layer 12 is removed; as shown in FIG. 2(e), the first plating layer 11 is etched to be patterned. a region covered by the photoresist layer 12; as shown in FIG. 2(f), a second photoresist layer 20 is disposed on the first layer line 13 to cover the first layer line 13; as shown in FIG. 2 The image is transferred to the second photoresist layer 20 to form at least one blind via 21 to communicate with the first layer trace 13; as shown in FIG. 2(h), a surface is disposed on the surface of the second photoresist layer 20. a second plating layer; as shown in FIG. 2(i), the plating is at least The first layer line 13 and the second plating layer 22 connected to the blind hole 21 are formed in the at least one blind hole 21 to form at least one conductive pillar 23; as shown in FIG. 2(j), a third photoresist layer is disposed. 24 is on the conductive pillar 23 and the second plating layer 22 after the plating; as shown in FIG. 2(k), the image is transferred to the third photoresist layer 24 to at least correspondingly cover the at least one blind hole 21; 2(l), etching the region of the second plated layer 22 after the plating is not covered by the third photoresist layer 24 after the image transfer; as shown in FIG. 3(m), removing the image after the image transfer a third photoresist layer 20; as shown in FIG. 3(n), the second photoresist layer 20 after the image transfer is removed; as shown in FIG. 3(o), a second layer substrate 30 is disposed on the first layer. a line 13 and the at least one via post 23 to cover the first layer line 13 and the at least one via post 23; as shown in FIG. 3(p), the second layer substrate 30 is laserly perforated At least one conductive pillar 23 exposes the surface of the second layer substrate 30; as shown in FIG. 3(q), a third plating layer 31 is disposed on the surface of the second layer substrate 30; as shown in FIG. 3(r), A fourth photoresist layer 32 is disposed on the surface of the third plating layer 31; As shown in FIG. 3(s), the image is transferred to the fourth photoresist layer 32 to pattern the fourth photoresist layer 32 to form a second layer trace pattern; as shown in FIG. 4(t), the third layer is electroplated. The plating layer 31 forms a second layer line 33 in a region covered by the fourth photoresist layer 32 after the third plating layer 31 is not patterned; as shown in FIG. 4(u), the patterned portion is removed. The fourth photoresist layer 32; as shown in FIG. 4(v), etches the region where the third plating layer 31 was originally covered by the patterned fourth photoresist layer 32.

In the respective steps of transferring the first to fourth photoresist layers 12, 20, 24, 32, the first to fourth photoresist layers 12, 20, 24, 32 are subjected to an exposure and development process to generate First to fourth photoresist layers of a particular image.

In the above steps of removing the first to fourth photoresist layers 12, 20, 24, 32, the first to fourth photoresist layers 12, 20, 24, 32 are removed by photoresist removal.

In the above respective steps of etching the first to third plating layers 11, 22, 31, the first to third plating layers 11, 22, 31 are removed by an etching liquid.

In the preferred embodiment, the first to fourth photoresist layers 12, 20, 24, 32 are dry films.

In the present invention, the second photoresist layer 20 is transferred by image to form the at least one blind via 21, and the at least one via post 23 is directly formed by electroplating in the at least one blind via 21, so that there is no The problem that the photoresist layer after the image transfer is not aligned with the blind hole 21 formed by the laser perforation. In addition, since the second layer substrate 30 is disposed after the at least one via post 23 is formed, the at least one via post 23 is exposed through the laser perforation to expose the surface of the second layer substrate 30, and the second layer of the substrate is plated. In the case of the pattern, it is not necessary to fill the depth of the blind hole 21, and the second layer line 33 formed after the plating can be made relatively flat. Therefore, in the process of connecting another circuit board with solder, the second layer line 33 can be stably contacted and soldered with another circuit board, and there is no surface unevenness resulting in poor soldering.

In the preferred embodiment, the third photoresist layer 24 after the image is transferred covers the at least one blind hole 21 to be larger than the inner diameter of the blind hole 21. In this way, after etching the region of the second plating layer 22 covered by the third photoresist layer 24 after the image transfer, the remaining second layer 22 after plating is not only connected to the via post 23, but also has The larger area provides the next step in making the second layer line 33, which can have a larger connection area for the second layer line 33 to be connected to the via post 23 to communicate the first layer line 13. That is, the area of the at least one via post 23 exposing the surface of the second layer substrate 30 is greater than the area of the inner diameter of the at least one blind via 21 . In this way, not only the blind hole filling hole is not bad, but also the electrical connection strength between the second layer line 33 and the first layer line 13 can be further improved, thereby improving the manufacturing yield of the solderless multilayer circuit board. .

Referring to FIG. 5, the present invention further provides a solderless pad multilayer circuit board including a substrate 10, a first layer line 13, at least one via post 23, a second layer substrate 30, and a second layer line. 33. The first layer line 13 is disposed on a surface of the substrate 10. The at least one via post 23 is connected to the first layer line 13. The second layer substrate 30 is disposed on the surface of the substrate 10 and covers the first layer line 13 and covers the at least one via post 23 . The at least one via post 23 exposes the surface of the second layer substrate 30, and the at least one via post 23 exposes the surface of the second layer substrate 30 to be larger than the at least one via post 23 and the first layer line 13 The contact area of the connection. The second layer line 33 is disposed on the surface of the second layer substrate 30, and connects the at least one conductive pillar 23 to expose a portion of the surface of the second layer substrate 30.

Because the at least one via post 23 is exposed to be coplanar with the surface of the second layer substrate 30 and the surface of the second layer substrate 30, the second layer line 33 can be formed flat when compared to another circuit board. Perform stable contact welding. And because the area of the conductive pillar 23 exposing the surface of the second layer substrate 30 is greater than the contact area of the at least one conductive pillar 23 and the first layer wiring, the second layer line 33 can be connected to the at least one conductive pillar. 23 is firmly connected to further connect the first layer of the wires more firmly, thereby improving the fabrication yield of the solderless multilayer circuit board.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention. A person skilled in the art can make some modifications or modifications to equivalent embodiments by using the above-disclosed technical contents without departing from the technical scope of the present invention, but without departing from the technical solution of the present invention, according to the present invention. Technical Substantials Any simple modifications, equivalent changes and modifications made to the above embodiments are still within the scope of the technical solutions of the present invention.

10‧‧‧Substrate
11‧‧‧First plating
12‧‧‧First photoresist layer
13‧‧‧First floor
20‧‧‧Second photoresist layer
21‧‧‧Blind holes
22‧‧‧Second plating
23‧‧‧Connecting column
24‧‧‧ Third photoresist layer
30‧‧‧Second substrate
31‧‧‧ Third plating
32‧‧‧fourth photoresist layer
33‧‧‧Second floor
40‧‧‧Substrate
41‧‧‧First plating
42‧‧‧First photoresist layer
43‧‧‧First floor
50‧‧‧Second substrate
51‧‧‧Second plating
52‧‧‧Blind holes
53‧‧‧second photoresist layer
54‧‧‧Second floor
60‧‧‧ boards
61‧‧‧ solder joints

1 is a flow chart of a preferred embodiment of a method for fabricating a solderless pad multilayer circuit board of the present invention. 2(a) to 2(l) are schematic diagrams showing the flow state of a preferred embodiment of the method for fabricating a solderless pad multilayer circuit board of the present invention. 3(m) to 3(s) are schematic diagrams showing the flow state of a preferred embodiment of the method for fabricating a solderless pad multilayer circuit board of the present invention. 4(t) to 4(v) are schematic diagrams showing the flow state of a preferred embodiment of the method for fabricating a solderless pad multilayer circuit board of the present invention. Figure 5 is a schematic illustration of a preferred embodiment of a solderless pad multilayer circuit board of the present invention. 6(a) to 6(i) are schematic flow charts showing a conventional method for manufacturing a solderless pad multilayer circuit board. 7(j)-7(m) are schematic flow diagrams of a conventional method for fabricating a solderless pad multilayer circuit board. FIG. 8 is a schematic view showing a blind hole of a conventional solderless pad multilayer circuit board. FIG. 9 is a schematic view showing the welding of the second layer circuit of the conventional solderless pad multilayer circuit board with another circuit board.

Claims (7)

A method for manufacturing a solderless multilayer circuit board includes the steps of: preparing a substrate, wherein a surface of the substrate is provided with a first plating layer and a first photoresist layer, wherein the first plating layer is disposed on the first light Between the resist layer and the substrate; transferring the first photoresist layer to pattern the first photoresist layer to form a first layer trace pattern; plating the first plating layer to the first plating layer Forming a first layer line in the patterned region of the first photoresist layer; removing the patterned first photoresist layer; etching the first photoresist layer to be patterned by the first photoresist layer Covering the area; providing a second photoresist layer on the first layer line to cover the first layer line; and transferring the second photoresist layer to form at least one blind via to connect the first layer line; Forming a second plating layer on the surface of the second photoresist layer; plating the first layer of the at least one blind via and the second plating layer to form at least one via post in the at least one blind via; a third photoresist layer on the via post and the electroplated first On the second plating layer; the image is transferred to the third photoresist layer to at least correspondingly cover the at least one blind via; the etched second electroplated layer region not covered by the third photoresist layer after the image transfer; a third photoresist layer after the image transfer; removing the second photoresist layer after the image transfer; and providing a second layer substrate on the first layer line and the at least one conductive pillar to cover the first a layer line and the at least one conductive pillar; the laser perforates the second layer of the substrate, exposing the at least one conductive pillar to the surface of the second layer of the substrate; and providing a third plating layer on the surface of the second layer of the substrate; a fourth photoresist layer is disposed on the surface of the third plating layer; the image is transferred to the fourth photoresist layer to pattern the fourth photoresist layer to form a second layer wiring pattern; and the third plating layer is plated to Forming a second layer line in the region where the third plating layer is not patterned by the fourth photoresist layer; removing the patterned fourth photoresist layer; etching the third plating layer to be patterned The area covered by the fourth photoresist layer. The method of manufacturing a non-pad multilayer circuit board according to claim 1, wherein the area of the third photoresist layer after the image transfer covers the at least one blind hole is larger than the area of the inner diameter of the at least one blind hole. The method of manufacturing a non-pad multilayer circuit board according to claim 1 or 2, wherein in the step of transferring the first to fourth photoresist layers, the first to fourth photoresist layers are exposed. The development process is to produce first to fourth photoresist layers having specific images. The method of manufacturing a non-pad multilayer circuit board according to claim 1 or 2, wherein in the step of removing the first to fourth photoresist layers, the first to fourth light is referred to as a photoresist. The barrier layer is removed. The method of manufacturing a padless multilayer circuit board according to claim 1 or 2, wherein in the respective steps of etching the first to third plating layers, the first to third plating layers are removed by an etching liquid. The method of manufacturing a padless multilayer circuit board according to claim 1 or 2, wherein the first to fourth photoresist layers are dry films. A solderless multilayer circuit board comprising: a substrate; a first layer of circuitry disposed on a surface of the substrate; at least one via pillar connected to the first layer of circuitry; and a second layer of substrate Providing on the surface of the substrate, covering the first layer of the line, and covering the at least one conductive pillar; wherein the at least one conductive pillar exposes the surface of the second layer of the substrate, and the at least one conductive pillar exposes the second layer The surface of the surface of the layer substrate is larger than the contact area of the at least one conductive pillar and the first layer; the second layer is disposed on the surface of the second substrate, and the at least one conductive pillar is connected to expose the A portion of the surface of the second substrate.