WO2013046442A1

WO2013046442A1 - Substrate and method for manufacturing same

Info

Publication number: WO2013046442A1
Application number: PCT/JP2011/072589
Authority: WO
Inventors: 秀吉瀧井; 典明種子; 道脇　茂; 満帆黒須; 佑一郎名屋
Original assignee: 株式会社メイコー
Priority date: 2011-09-30
Filing date: 2011-09-30
Publication date: 2013-04-04
Also published as: CN103828494A; TW201330715A

Abstract

This substrate is provided with: an insulating base material (2); conductive layers (16) which are pattern-formed on both the surfaces of the insulating base material (2), and have respective rear surfaces in close contact with the insulating base material (2); a through hole (11) that penetrates the insulating base material (2) and the conductive layers (16); and plating films (12), which are respectively formed continuously on the inner surface of the through hole (11) and the front surfaces of the conductive layers (16) on both the surfaces.

Description

Substrate and manufacturing method thereof

The present invention relates to a substrate having a through hole and a manufacturing method thereof.

Conventionally, in order to achieve electrical connection between layers of a multilayer substrate, a through hole penetrating an insulating layer and an insulating base material patterned on both surfaces is formed, and plating is performed in the through hole. Conduction is achieved by connecting the inner surface of the conductive layer formed as a through hole and plating. Thereby, an electrical interlayer connection is possible through plating in the through hole.

This through hole is often formed using a drill bit. Therefore, immediately after processing, chips (smear) are generated in the through hole, and the chips adhere to the through hole due to heat during processing. is doing. If this smear is not removed, poor plating connection may occur during the plating process to the through hole, and a smear removal step called desmear treatment is necessary. That is, if the smear remains attached to the inner surface of the conductive layer, a connection failure occurs between the conductive layer and the plating.

As the desmear treatment, permanganic acid, chromic acid or the like is used. As the pretreatment, it may be washed with an alkali detergent containing a surfactant and dried (for example, see Patent Document 1).

However, if the desmear process is not required, the manufacturing process is simplified and the productivity is improved. In particular, the desmear process requires a chemical solution for smear decomposition as described above, and has a high environmental load.

JP-A-5-37137

DETAILED DESCRIPTION OF THE INVENTION The present invention is a substrate and method for manufacturing the same that can reliably achieve interlayer connection without performing desmearing when plating through holes.

In the present invention, an insulating base material, a conductive layer that is patterned on both surfaces of the insulating base material, and a back surface is in close contact with the insulating base material, a through hole that penetrates the insulating base material and the conductive layer, There is provided a substrate comprising a plating film formed continuously on the inner surface of the through hole and on the respective surfaces of the conductive layer on both surfaces.

In addition, a conductive layer forming step of forming the conductive layer by partially removing the metal film with respect to the insulating base having the metal film attached to both surfaces, and each of the insulating base and the conductive layer A through-hole forming step for forming a through-hole penetrating through, an insulating layer forming step for forming an insulating layer by applying a first insulating resin to each of both surfaces of the insulating base, and at the same time as the insulating layer forming step or A via hole forming step of forming a via hole exposing the surface of the conductive layer in which the through hole is formed; and the via hole exposed at least on the inner surface of the through hole and on both surfaces of the insulating base. There is provided a method for manufacturing a substrate, comprising: a plating step of continuously forming a plating film on each of the surfaces of the conductive layer.

Preferably, in the insulating layer forming step, the first insulating resin is applied by an inkjet method, and the via hole is formed simultaneously with the application of the first insulating resin.

According to the present invention, the plating film is formed on the surface of each conductive layer patterned on both surfaces of the insulating substrate. For this reason, even if it is in the state in which the smear adhered in the through-hole, the electrical connection between both surfaces through an insulating base material can be ensured. That is, since the interlayer connection can be realized without going through the desmear process, the manufacturing process is simplified and the productivity is improved. Moreover, the chemical solution for the desmear process becomes unnecessary, and the environmental load can be reduced.

Further, if the insulating layer is formed by an ink jet method, a via hole can be formed simultaneously with the formation of the insulating layer. This eliminates the need for a step of forming a separate via hole with a laser or the like, makes it relatively inexpensive, and simplifies the manufacturing process.

1 is an enlarged schematic view of a substrate according to the present invention. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order. It is the schematic which shows the manufacturing method of the board | substrate concerning this invention in order.

As shown in FIG. 1, the substrate according to the present invention has an insulating base material 2 and conductive layers 16 patterned on both surfaces of the insulating base material. That is, the back surface of the conductive layer 16 (inner layer circuit 3 described later) is in close contact with the insulating substrate 2. Note that the insulating layer 5 is formed on the conductive layer 16 (on the insulating base material 2 for a portion where no pattern is formed). The insulating substrate 2 and the conductive layer 16 are provided with through holes 11 penetrating them. A via hole 6 is formed in the insulating layer 5 so as to communicate with the through hole 11. A plating film is continuously formed on the inner surface of the through hole 11, the inner surface of the via hole 6, and the surface of the insulating layer 5 by plating.

Here, when the via hole 6 is formed, the surface of the conductive layer 16 (the surface with respect to the back surface in close contact with the insulating base material 2) is exposed, so that a part of the plating film 12 is exposed to the exposed surface 16a of the conductive layer 16. Is also formed.

As described above, the plating film 12 is formed on the surface of each conductive layer 16 patterned on both surfaces of the insulating substrate 2. In other words, even when smear is generated on the inner surface of the conductive layer 16 on the through hole 11 side when the through hole 11 is formed, the electrical conductivity through the relatively smooth surface of the conductive layer 16 and the plating film 12 is increased. Connection is possible. For this reason, even if it is in the state which the smear adhered in the through hole 11, the electrical connection between both surfaces through the insulating base material 2 can be ensured. Thereby, the interlayer connection can be realized without going through the desmear process, so that the manufacturing process is simplified and the productivity is improved. Moreover, the chemical solution for the desmear process becomes unnecessary, and the environmental load can be reduced.

Below, the manufacturing method of the board | substrate which concerns on this invention is demonstrated.
In the method for manufacturing a substrate according to the present invention, first, a conductive layer forming step is performed. In the conductive layer forming step, first, as shown in FIG. 2, an insulating base material 2 having metal films 1 attached on both sides is prepared. The metal film 1 is, for example, a copper foil. Then, as shown in FIG. 3, the metal film 1 is partially removed to form a patterned inner layer circuit 3 (the conductive layer 16 described above).

Next, a through hole forming process is performed. In this through hole forming step, as shown in FIG. 4, a through hole 11 penetrating each of the insulating base material 2 and the inner layer circuit 3 is formed. The through hole 11 is formed using, for example, a drill bit.

Next, an insulating layer forming step is performed. In the insulating layer forming step, for example, as shown in FIG. 5, the insulating layer 5 is formed by applying the first insulating resin 4 to both surfaces of the insulating base material 2 by the ink jet method. The first insulating resin 4 is ejected from the nozzle 7 of the ejection device 8 using a known ink jet device, and is impacted on the insulating substrate 2 (or the inner layer circuit 3). The nozzle 7 moves in one direction with respect to the insulating substrate 2 (in the direction of arrow A in FIG. 5). At this time, using the characteristics of the ink jet system, the first insulating resin 4 is selectively impacted on the insulating base 2 and simultaneously the via hole 6 is formed. The via hole 6 is formed at a position where the inner layer circuit 3 is partially exposed. Therefore, the via hole 6 is formed at the same time as the insulating layer 5 is formed by applying the first insulating resin. As described above, if the insulating layer 5 is formed by the ink jet method, a process of forming the via hole 6 separately by a laser or the like is not necessary, and the manufacturing process can be simplified because the cost becomes relatively low. The insulating layer 5 is formed on one side of the insulating base 2 and finally formed on both sides. After this step, as shown in FIG. 6, the insulating layer 5 in which the via hole 6 is formed is formed. Thus, if an ink jet system is adopted, a via hole forming process can be performed simultaneously.

Note that the insulating layer 5 may be formed by screen printing. In this case, after the insulating layer 5 is once formed, a via hole 6 is separately formed as a via hole forming step.

Here, the via hole 6 formed in the via hole forming step is formed so that the surface 3a of the inner layer circuit 3 is exposed, regardless of whether it is formed by the above-described ink jet or by processing after screen printing. The

When inkjet is used in the insulating layer forming step, in order to accurately form the via hole 6 or to form the small diameter via hole 6, it is necessary to increase the resolution by reducing the droplet of the first insulating resin 4 by the inkjet method. It is. As this method, there is a method of simply reducing the nozzle pitch of the inkjet head. Alternatively, there are a method of reducing the substantial nozzle pitch by combining a plurality of nozzle heads and shifting the nozzle position, or attaching the heads obliquely with respect to the head moving direction. In the case of using such a method, it is necessary to shift the ejection timing of the liquid droplets for landing, and therefore it is necessary to be able to cope with the computer that controls the apparatus and its program.

Also, in order to support the ink jet system, the first insulating resin 4 to be applied by injection is of a viscosity that can be used in an ink jet apparatus. In particular, wetting and spreading properties when the first insulating resin 4 forming the insulating layer 5 has landed on both the insulating base material 2 and the inner layer circuit 3 are important. If the wetting and spreading property is large, the first insulating resin 4 flows out into the via hole 6 to be formed or the outside of the insulating base material 2 and becomes a factor of degrading the resolution. Or control of application | coating thickness becomes difficult. If the wettability is small, in an extreme case, the liquid droplets may be cured while remaining in a ball shape or repel the liquid.

In order to optimize the wettability, the wettability of the insulating base material 2 to which the first insulating resin 4 is applied may be optimized. In particular, it is useful to optimize such wettability for the insulating base material 2 in which the resin (insulating base material 2) and copper (inner layer circuit 3) on which the present invention is based are mixed. It is. This optimization may be performed by performing corona treatment, low-pressure UV irradiation treatment, or plasma treatment on the surface of the insulating substrate 2 on which the inner layer circuit 3 is formed after the inner layer circuit forming step and before the insulating layer forming step. Thereby, the surface modification of the insulating base material 2 can be performed and the wettability with respect to the 1st insulating resin 4 can be optimized. Corona treatment is preferable in consideration of the price and running cost of the apparatus.

Further, the inkjet device further includes an irradiation device 9 for irradiating ultraviolet rays, and this irradiation device 9 can move following the ejection device 8 in the movement direction A. Specifically, the irradiation device 9 is mounted on the extension of the ink jet head of the ink jet device, and when the ink jet head moves, the irradiation device 9 moves at the same time. If the first insulating resin 4 is an ultraviolet curable resin, the impact position is irradiated with the ultraviolet light P immediately after the first insulating resin 4 is impacted on the surface of the insulating base 2. Accordingly, the first insulating resin 4 is cured or semi-cured, and the first insulating resin 4 can be prevented from spreading more than necessary. This hardening should just be hardened to the extent that the resin 4 does not flow. In this way, by curing the resin 4 immediately after impacting, the pre-curing step that is necessary when applying the single side to the insulating base 2 is not necessary. In addition, it is preferable that the first insulating resin 4 is an ultraviolet ray and a thermosetting resin, and the first insulating resin 4 is cured by performing a heat treatment after the insulating layer 5 is formed.

Further, as described above, since the inner layer circuit 3 is formed on the insulating base material 2 in the insulating layer forming step, it has an uneven shape. When screen printing or the like is performed on such a portion, uneven shapes remain on the printed surface. If an inkjet system is used, more resin can be applied aiming at the concave and convex portions, so that the surface can be made uniform.

Also, as a method for applying the first insulating resin 4, there is a method in which the first insulating resin 4 is landed in a flying manner and dried, and the second coating is aimed at these gaps.

When a resin layer having a certain thickness (about 40 μm to 80 μm) is formed as in the build-up insulating layer, particularly when the droplets are made small to increase the resolution, the required insulating layer thickness is 1 It cannot be obtained only by one application. In this case, there is a method of applying a plurality of times or obtaining a required thickness by mounting a plurality of heads. However, in order to keep the shape of the opening not to be applied, once it is applied, it is cured to some extent with ultraviolet rays or the like. A method of applying the second and subsequent times after holding is preferable.

After the insulating layer forming process described above, a plating process is performed. In this plating process, as shown in FIG. 7, the surface of the insulating layer 5, the inner surface of the through hole 11, the inner surface of the via hole 6, and the exposed surface 3a of the inner layer circuit 3 are shown in FIG. A plating film 12 is formed on the exposed surface 16a) of the conductive layer. The plating film 12 is made of a conductive metal, for example, copper. Then, the plating film 12 is partially removed using etching or the like, and an outer layer circuit 13 is formed on the surface of the insulating layer 5 as shown in FIG.

Thus, since the plating film 12 is formed on the exposed surface 3a of the inner layer circuit 3, even when smear is generated on the inner surface of the conductive layer 16 on the through hole 11 side during the formation of the through hole 11, the comparison is made. Electrical connection through the surface 3a of the inner smooth circuit 3 and the plating film 12 becomes possible. For this reason, even if it is in the state which the smear adhered in the through hole 11, the electrical connection between both surfaces through the insulating base material 2 can be ensured. Thereby, the interlayer connection can be realized without going through the desmear process, so that the manufacturing process is simplified and the productivity is improved. Moreover, the chemical solution for the desmear process becomes unnecessary, and the environmental load can be reduced.

Then, a resist layer forming process is performed. In this resist layer forming step, as shown in FIG. 9, the second insulating resin 14 is selectively applied to the outer layer circuit 13 by an ink jet method. Generally, it is applied leaving at least the via hole 6 and the through hole 11. The second insulating resin 14 is applied on the outer layer circuit 13 to form a resist layer 15. In this manner, the resist layer 15 can also be formed by using an ink jet method to form a resist layer (solder resist) 15 having an opening in the via hole, and a process for opening the via hole in the resist separately. It becomes unnecessary. About the application | coating of the 2nd insulating resin 14 by an inkjet system, the method similar to the 1st insulating resin 4 mentioned above can be used, and the same effect can be acquired. When all the resist layers 15 are formed, a substrate as shown in FIG. 10 is formed.

DESCRIPTION OF SYMBOLS 1 Metal film 2 Insulating base material 3 Inner layer circuit 4 1st insulating resin 5 Insulating layer 6 Via hole 7 Nozzle 8 Ejecting device 9 Irradiating device 11 Through hole 12 Plating film 13 Outer layer circuit 14 Second insulating resin 15 Resist layer 16 Conductive layer P UV

Claims

An insulating substrate;
A conductive layer that is patterned on both sides of the insulating substrate, and whose back surface is in close contact with the insulating substrate;
A through hole penetrating the insulating substrate and the conductive layer;
A substrate comprising: a plating film formed continuously on the inner surface of the through hole and on the respective surfaces of the conductive layer on both sides.
A conductive layer forming step of forming the conductive layer by partially removing the metal film with respect to the insulating base material on which metal films are attached on both sides;
A through hole forming step of forming a through hole penetrating each of the insulating base and the conductive layer;
An insulating layer forming step of forming an insulating layer by applying a first insulating resin to each of both surfaces of the insulating base;
A via hole forming step of forming a via hole exposing the surface of the conductive layer in which the through hole is formed simultaneously with or after the insulating layer forming step;
And a plating step of continuously forming a plating film on each of the surfaces of the conductive layer exposed in at least the inner surface of the through hole and the via hole on both surfaces of the insulating base. Item 2. A method for manufacturing a substrate according to Item 1.
3. The substrate manufacturing method according to claim 2, wherein in the insulating layer forming step, the first insulating resin is applied by an ink jet method, and the via hole is formed simultaneously with the application of the first insulating resin. Method.