JPH053388A - Manufacture of multilayer printed board and insulating layer for multilayer printed board - Google Patents

Abstract

PURPOSE:To secure required insulation and elevate the close adhesion with the electroless plated layer on the surface side, concerning the manufacture of an insulating layer for a multilayer printed board and the multilayer printed board. CONSTITUTION:In an insulating layer for a multilayer printed board, wherein a resin material 3a which has photosetting property and insulating property and filler ingredients 3b to stabilize this are mixed, the density of the filler ingredients 3b is made high on the surface side and low on the inner face side. Moreover, in the manufacture of a piling type of multilayer, it is so constituted as to form an insulating layer for a multilayer printed board in an insulating layer formation process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-layer printed circuit board which is mainly manufactured by a stacking method and an insulating layer applied to the multi-layer printed circuit board.

[0002]

2. Description of the Related Art Conventionally, in a multilayer printed circuit board, conductor layers separated by an insulating layer are connected to each other by a plated layer of a through hole or a conductor filled in a via hole.

However, in this case, since the through holes and the via holes are formed by so-called drilling using a drill, there is a large limit in reducing the diameter of these holes. The diameter of the land that needs to be formed large is 0.
There is an even greater limit to making the diameter smaller than 3 to 0.5 mm.

In order to break through these limits, it is currently attempted to form a multilayer printed circuit board by a stacking method. In the stacking method, for example, as shown in FIG.
First layer forming step (a) of forming a conductor pattern 102 by printing a conductor layer on the surface of the insulator 101 and etching the conductor pattern into a predetermined pattern, the insulator 101 and the conductor pattern 1.
Insulating layer forming step (b) of forming the photosensitive insulating layer 103 on the surface of 02, exposing and curing a required portion of the insulating layer 103, removing the uncured portion, and forming a hole 104 through the insulating layer 103. Forming baking / developing step (c), insulating layer 10
The surface of 3 is polished with a brush, or the insulating layer 103
When a filler such as calcium carbonate is mixed in the surface, the surface treatment step (d) of roughening by removing the filler component on the surface with an acid, and the surface of the insulating layer 103 by electroless plating Electroless plating step (e) for forming the electrolytic plating layer 105, electrolytic plating step (f) for depositing an electrolytic plating layer on the surface of the electroless plating layer 105 and growing it to a plating layer 106 of a required thickness, plating layer Second etching of 106 to form the conductor pattern 107 on the front surface side
After the layer forming step (g), the first-layer conductor pattern 102 and the second-layer conductor pattern 107 are connected via the plated layer 106 in the hole 104. When forming a conductor pattern of a third layer or more, the procedure from the insulating layer forming step (b) to the second layer forming step (f) is repeated every time one layer is stacked.

In the printing / developing step (c), since the fine holes 104 having a diameter of about 0.15 to 0.25 mm can be formed, the diameter of the lands of the conductor patterns 102 and 107 can be reduced to about 0.2 mm. Therefore, the circuit density can be significantly increased.

[0006]

In the surface treatment step (d), when the surface of the insulating layer 103 is roughened by polishing, as shown in FIG.
A V-shaped scratch 103f is attached to the surface of 03. When the electroless plating layer 105 is adhered to the surface of the insulating layer 103 having such a scratch 103f, the conductor pattern 107 is applied to the insulating layer 103 when heated later, for example, when mounting components.
The product may be easily peeled off, and the reliability of the product may be impaired.

In the surface treatment step (d), the filler component on the surface mixed in the insulating layer 103 is chromic acid,
In the case of elution and removal with an acidic treatment liquid such as hydrochloric acid, after the filler component is removed, as shown in FIG. 6, in addition to the V-shaped hole 103c, the hole 10 whose inside is larger than the inlet 10 is formed.
3d, a hole 103e or the like that is obliquely recessed from the entrance may be provided in a cave. The hole 103d whose inside is enlarged in this way
Or an electroless plating layer 105 on the surface of the insulating layer 103 having a hole having a complicated shape such as a hole 103e obliquely recessed from the entrance.
In the case of adhering, since the electroless plating layer 105 enters into the hole of the complicated shape and is less likely to be peeled off, the adhesiveness between the insulating layer 103 and the electroless plating layer 105 is higher than that in the case of polishing. Is increased.

However, in general, in order to ensure the insulating property of the insulating layer 103, the density of the filler component is kept low, so that the distribution density of the holes 103c to 103e becomes low and the density of the insulating layer 103 and the electrolytic plating layer 105 is reduced. The bonding strength is, for example, about 0.5 to 1.0 kgf / cm, and it is practically unsatisfactory.

The present invention has been made in view of the above circumstances, and is a multi-layer structure capable of ensuring a required insulating property and enhancing the adhesion with the electroless plating layer on the surface side. An object of the present invention is to provide a method for manufacturing a printed board and an insulating layer for a multilayer printed board.

[0010]

In order to achieve the above object, the present invention is, as shown in FIG. 1, a photosensitive curable resin containing a filler component 3b on an insulating material 1 on which a conductor pattern 2 is formed. An insulating layer 3 formed by exposing the material 3a to light;
In the method of manufacturing a multi-layer printed circuit board of a stacking type in which a conductor pattern 7 formed after removing the filler component 3b on the surface of the insulating layer 3 is sequentially stacked, the insulating layer 3 has a low density of the filler component 3b. After forming the inner surface layer 32, the density of the filler component 3b is reduced to the inner surface layer 3
The surface layer 31 higher than 2 is formed. The inner surface layer 32 and the surface layer 31 of the insulating layer 3 can be formed by drying a dry film or a liquid resin. Moreover, the removal of the filler component 3b can be performed chemically using an acidic solution such as chromic acid.

[0011]

In the present invention, the required insulating property is ensured in the portion on the inner surface side where the filler component 3b is low. Moreover, since the density of the filler component 3b is high on the surface side, if the filler component 3b exposed on the surface is removed, the surface of the insulating layer 3 has an enlarged hole inside than the inlet, a hole obliquely recessed from the inlet, etc. The holes having a complicated shape are distributed at high density, and the bonding strength with the electroless plating layer attached to this surface is enhanced.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. Next, a method for manufacturing a multilayer printed board according to an embodiment of the present invention will be described with reference to FIG.

The method of manufacturing the multilayer printed circuit board is the same as the conventional method of manufacturing the multilayer printed circuit board of the stacking type except that the insulating layer 3 according to the embodiment of the present invention is used as the insulating layer 3. . That is, for example, as shown in FIG. 1, a conductor layer is printed on the surface of an insulating material 1 and etched into a predetermined pattern to form a conductor pattern 2.
A layer forming step (a), an insulating layer forming step (b) in which the insulating layer 3 is laminated on the surfaces of the insulating material 1 and the conductor pattern 2, and a desired portion of the insulating layer 3 is exposed and cured,
A baking / developing step (c) of removing the uncured portion to form a hole 4 penetrating the insulating layer 3, a surface of the insulating layer 3 roughening the surface of the insulating layer 3 by removing the filler component 3b. Treatment step (d), electroless plating step (e) of forming the electroless copper plating layer 5 on the surface side by electroless plating on the surface of the insulating layer 3, and electrolytic copper plating layer on the surface of the electroless copper plating layer 5. After the electrolytic plating step (f) of adhering and growing the copper plating layer 6 of a required thickness, the second layer forming step (g) of etching the copper plating layer 6 to form the conductor pattern 7 on the front side, One-layer conductor pattern 2 and second-layer conductor pattern 7
And are laminated and connected via the copper plating layer 6 in the hole 4.

When forming a conductor pattern of a third layer or more, the procedure from the insulating layer forming step (b) to the second layer forming step (f) is repeated every time one layer is stacked. In the above, the insulating layer 3 is made of a resin material 3a having a photo-curing property and an insulating property as shown in an enlarged view in FIG. 1 or 2.
In addition, a dry film in which a surface layer 31 in which a filler component 3b for stabilizing the same is mixed at a high density and an inner surface layer 32 in which a filler component 3b is mixed at a low density in a resin material 3a having photocurability and insulation are laminated. Composed of.

The thickness of the inner surface layer 32 is appropriately set depending on the required insulating property and the blending ratio of the filler component 3b. In addition, the thickness of the surface layer 31 may be set to a level that allows the surface layer 31 to remain during the surface treatment.

In the surface treatment step (d), the filler component 3b made of magnesium carbonate or calcium carbonate having an average particle diameter of 0.7 μm is dissolved and removed in an acidic treatment liquid such as chromic acid or hydrochloric acid, and then removed as shown in FIG. As shown in detail in
On the surface of the insulating layer 3, there are formed a U-shaped or V-shaped hole 3c having an opening, a hole 3d having an inner side larger than the entrance, and a hole 3e obliquely recessed from the entrance.

Here, the surface layer 31 contains the filler component 3b.
Are densely mixed with each other, so that the holes 3c to 3e are formed on the surface of the holes 3c to 3e, and in particular, the hole 3 whose inside is larger than the inlet 3a.
d, the holes 3e and the like that are obliquely recessed from the inlet are distributed at high density. Therefore, in the subsequent electroless plating step (e), the electroless copper-plated layer 5 has a hole 3d in which the inside is enlarged from the inlet or a hole 3e obliquely recessed from the inlet.
The copper plating layer 6 formed in the electrolytic plating step (f) is 1.0 to
It is firmly joined with a joining strength of about 2.0 kgf / cm or more.
Since this bonding strength increases / decreases in accordance with the increase / decrease in the filler component density of the surface layer 31, by adjusting the filler component density of the surface layer 31, 1.5 kgf /
A bonding strength of about cm or more can be stably obtained.

Further, since the inner surface layer 32 has a required insulating property, the insulating property is not impaired even if the filler component density of the surface layer 31 is increased. Although the insulating layer 3 is composed of a dry film having a two-layer structure in the above-mentioned embodiment, the inner surface layer 32 is composed of dry film, and after the inner surface layer 32 is laminated in the insulating layer forming step (b), the filler is added. The liquid resin material 3a in which is dispersed at high density may be applied to the surface of the inner surface layer 32 by, for example, a spin coater, a roll coater, or the like. Alternatively, the liquid inner surface layer 32 may be applied and dried, and the liquid surface layer 31 may be applied to the surface thereof to form the insulating layer 3.

[0019]

As described above, the insulating layer for a multilayer printed circuit board and the method for manufacturing a multilayer printed circuit board according to the present invention make the density of the filler component low on the inner surface side, so that it is required at the inner surface side portion. Insulation properties can be secured, and the density of the filler component is increased on the surface side, so by eluting the filler component on the surface side, a hole that is wider than the inside of the inlet, it was recessed diagonally from the inlet Holes with complicated shapes such as holes can be formed at high density, and the bonding strength with the electroless plating layer that will be adhered to the surface later is increased and the bonding strength with the conductor pattern formed on the surface side is increased. be able to. As a result, peeling of the conductor pattern can be prevented and the reliability of the product can be improved without impairing the insulating property.

[Brief description of drawings]

FIG. 1 is a flow chart of a method for manufacturing a multilayer printed circuit board according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an example of an insulating layer of the present invention.

FIG. 3 is a schematic view of an example after surface treatment.

FIG. 4 is a flow chart of a conventional manufacturing method using a stacking method.

FIG. 5 is a schematic view of a conventional example after surface treatment by polishing.

FIG. 6 is a schematic diagram of a conventional example after surface treatment by elution of filler components.

[Explanation of symbols]

1 insulation 2 conductor pattern 3 insulating layers 3a Resin material 3b Filler component 7 conductor pattern 31 surface layer 32 inner layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hitoshi Yuyama             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (4)

[Claims] 1. An insulating material (1) having a conductor pattern (2) formed thereon.
An insulating layer (3) formed by exposing a photosensitive curable resin material (3a) containing a filler component (3b) thereon, and the insulating layer (3)
In the method for manufacturing a multi-layer printed circuit board of a stacking method, the conductive pattern (7) formed after removing the filler component (3b) on the surface of the
As the (3), the inner surface layer (32) having a low density of the filler component (3b)
The method for producing a multilayer printed board, comprising: forming a surface layer (31) having a density of the filler component (3b) higher than that of the inner surface layer (32) after forming the. 2. The inner layer (32) and the surface layer (31) are formed by drying a dry film or a liquid resin.
A method for manufacturing the multilayer printed circuit board according to. 3. The method for producing a multilayer printed circuit board according to claim 1, wherein the removal of the filler component (3b) is performed chemically. 4. A resin material having a photo-curing property and an insulating property.
(3a) and a filler component (3b) for stabilizing it are mixed in a multilayer printed circuit board insulating layer, the filler component (3
An insulating layer for a multilayer printed circuit board, wherein the density of b) is high on the surface side and low on the inner surface side.