JP2001044627A - Wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire a method for manufacturing a wiring board and a wiring board securing a satisfactory adhesion between a conductive-layer surface and an interlayer insulation layer. SOLUTION: A method for manufacturing a wiring board laminating an interlayer insulation layer 5 on a lower layer pattern 2 wherein a surface of the lower layer pattern 2 is roughened, tin displacement is plated on the surface of the roughened lower pattern 2, and then the interlayer insulation layer 5 is laminated on the lower layer pattern 2. Adhesion between the lower layer pattern 2 and the interlayer insulation layer 5 is secured satisfactorily because the surface of the lower layer 2 covered by tin prevents formation of metal oxide on the surface of the lower layer pattern 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board formed by laminating an insulating layer on a conductor layer, and a method of manufacturing the same.
More specifically, the present invention relates to a wiring board which ensures the close contact between a conductor layer and an insulating layer thereover, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a wiring board has been manufactured by laminating a conductor layer and an insulating layer. Here, the surface of the conductor layer is usually roughened before the insulating layer is laminated on the conductor layer. This is for improving the adhesion between the conductor layer and the insulating layer. Roughening is usually performed by etching with some surface treatment agent. As a surface treatment agent for this purpose, there is one described in JP-A-7-292483. In the same publication, the surface treating agent can form deep irregularities on the surface of a conductor layer such as copper.

[0003]

However, even if the surface of the conductor layer is roughened with the above-mentioned surface treating agent, the adhesion is still insufficient. For example, when heat is applied in a later process (reflow for component mounting (230 to 250 ° C)
Etc.), and the conductor layer and the insulating layer are peeled off and swelled. As one of the causes, it is considered that the surface of the conductor layer is oxidized after the surface is roughened to form an oxide film.

The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide a method of manufacturing a wiring board and a wiring board which have sufficient adhesion between the surface of the conductor layer and the insulating layer.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a method of manufacturing a wiring board by laminating an insulating layer on a surface of a conductive layer. The gist of the present invention is to apply tin displacement plating to the surface of a roughened and roughened conductor layer, and then to laminate an insulating layer on the conductor layer.

In this method, first, the surface of the conductor layer is roughened. At this time, for example, the above-described surface treatment agent can be used. Thereby, deep irregularities are formed on the surface of the conductor layer. However, in this state, an oxide film is formed on the surface of the conductor layer. Therefore, the surface of the roughened conductor layer is subjected to tin displacement plating. Thereby, since the surface of the conductor layer is covered with tin, formation of an oxide film on the surface of the conductor layer is prevented. After that, an insulating layer is laminated on the conductor layer. For this reason, the conductor layer and the insulating layer are in direct contact with each other without an oxide film. As described above, the adhesion between the conductor layer and the insulating layer can be made sufficient.

At this time, the plating thickness in the tin displacement plating is preferably set to 0.10 to 0.13 μm. if,
If the plating thickness is smaller than 0.10 μm, the tin displacement plating is still insufficient. Therefore, the effect of improving the adhesion between the surface of the conductor layer and the insulating layer cannot be sufficiently obtained.

Further, since tin is adhered to the conductor layer by displacement plating, when the plating thickness is greater than 0.13 μm, dissolution of a portion of the surface of the uneven conductor layer which is not covered with tin becomes remarkable. Would. As a result, the surface of the uneven conductive layer is likely to collapse. Therefore, when the insulating layer is laminated on the conductor layer, the anchor effect due to the unevenness formed on the surface of the conductor layer is weakened, and the effect of improving the adhesion between the surface of the conductor layer and the insulating layer cannot be sufficiently obtained.

Further, according to the wiring board of the present invention, in a wiring board formed by laminating an insulating layer on a conductor layer, the surface of the conductor layer is roughened and tin-plated to form an overhang. It is what makes.

Here, the overhang state is, for example,
This is a state in which plated metal tin is deposited on the side surfaces of the protrusions formed by roughening the surface of the conductor layer in an uneven manner and protrudes laterally.

In the wiring board according to the present invention, the resin of the insulating layer enters into the deep portion of the overhanging tin plating. For this reason, even if the force for peeling the insulating layer from the conductive layer acts on the wiring board in a later step, the overhanging portion and the resin of the insulating layer penetrating into the overhang shape are caught, so that the insulation The layer does not easily peel off from the conductor layer. Therefore, the adhesion between the conductor layer and the insulating layer is considerably higher than that of the conventional wiring board.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a substrate in which a lower layer pattern is formed on an original substrate is prepared. The starting material is a glass epoxy substrate or a copper-clad laminate obtained by laminating a copper foil (about 18 μm thick) on a substrate 1 made of BT (bismaleimide triazine) resin. Pattern etching is performed on the copper foil of the copper-clad laminate by a method usually used to form a copper lower layer pattern 2 (FIG. 1).

Next, the surface of the lower layer pattern 2 is roughened. Such surface roughening is performed by using CZ-8100 as a surface treatment agent.
(Manufactured by MEC Corporation). Then, as shown in FIG. 2, the surface of lower layer pattern 2 is roughened.

However, in this state, the lower layer pattern 2 is oxidized to form an oxide film.
Therefore, next, tin substitution plating is performed on the roughened lower layer pattern 2. For such tin displacement plating, a plating solution containing tin borofluoride and thiourea is used. Then, as shown in an enlarged manner in FIG. 3, a metal tin plating layer 4 is formed in an uneven shape on the surface of the projection 3 formed on the lower layer pattern 2 by roughening.

[0015] Finally, an interlayer insulating layer 5 is formed on the lower layer pattern 2. This formation is performed by a method of applying a varnish-like material based on an epoxy resin by roll coating to a thickness of 80 μm, or a dry film (BF-80 manufactured by Hitachi Chemical).
(Thickness of 00, 70 μm) by coating with a vacuum laminator. Then, an interlayer insulating layer 5 is formed as shown in FIG.

The wiring board formed by the above method is shown in FIG.
As shown in FIG. 1, a lower layer pattern 2 having a roughened surface is formed on a substrate 1. Then, tin displacement plating is applied to the surface of the lower layer pattern 2 to form a plating layer 4 (FIG. 6).
Reference) is formed. An interlayer insulating layer 5 is laminated on the plated lower layer pattern 4.
In FIG. 4, the plating layer 4 is not shown because it is extremely thinner than the lower layer pattern 2, the substrate 1, and the like. Further, as shown in FIG. 6 in which the surface portion of the lower layer pattern 2 is enlarged,
The surface of the lower layer pattern 2 is roughened to form the projections 3, and further, the plating layer 4 is formed on the surface of the projections 3 in an uneven manner. The plating layer 4 is formed on the side surface of the protrusion 3 in an overhang shape. Further, the interlayer insulating layer 5
Resin has entered between the uneven plating layers 4.

In the wiring board having the above structure, the lower layer pattern 2
Is covered with the tin plating layer 4, so that an oxide film is not easily formed. Therefore, the lower layer pattern 2 and the interlayer insulating layer 5 are in close contact with each other without an oxide film.
As a result, a wiring board in which the lower layer pattern 2 and the interlayer insulating layer 5 are more firmly adhered is obtained.

According to the wiring board having the above structure, FIG.
As shown in the figure, the resin of the interlayer insulating layer 5 penetrates into the depth of the overhang-shaped plating layer 4. Therefore, even in a later step, even if a force for peeling the interlayer insulating layer 5 from the lower layer pattern 2 acts on the wiring board, the interlayer insulating layer 5 penetrating into the overhang-shaped plating layer 4 formed on the side surface of the protrusion 3. Of the interlayer insulating layer 5
Does not peel off easily. Therefore, the adhesion between the lower layer pattern 2 and the interlayer insulating layer 5 is considerably higher than that of the conventional wiring board.

Further, in order to examine the optimum plating thickness in the case of tin displacement plating, a test was performed on the relationship between the plating thickness by tin displacement plating and the adhesion between the lower layer pattern 2 and the interlayer insulating layer 5. This test was performed by applying heat of reflow to a wiring board plated with tin within a range of various plating thicknesses of 0 to 0.3 μm and measuring the occurrence of blistering. As a test piece for this test, a wiring board for a mobile phone was used, and the reflow temperature was set to a maximum of 240 ° C. by IR reflow. The plating thickness was calculated from the macroscopic amount of tin per unit area of the wiring board, and the amount of tin per unit area was controlled by the plating time. FIG.
Is a graph showing the results. The vertical axis of this graph is the occurrence rate (%) of swelling of the wiring board after reflow, and the horizontal axis is the plating thickness (μm) of tin displacement plating. According to FIG. 5, when the plating thickness is 0.10 to 0.13 μm, the occurrence rate of blister due to reflow is almost 0%. Therefore, at this time, it can be seen that the adhesion between the lower layer pattern 2 and the interlayer insulating layer 5 is the highest. The following can be considered as the reason.

That is, if it is smaller than 0.10 μm, the tin displacement plating is still insufficient. Therefore, the effect of the adhesion between the lower layer pattern 2 and the interlayer insulating layer 5 becomes insufficient.

Further, when the tin displacement plating is performed, tin adheres to the lower layer pattern 2 and accordingly, the lower layer pattern 2
Of copper is dissolved in the plating solution. Therefore, in FIG. 3, when the plating thickness is larger than 0.13 μm, the protrusion 3
Of the parts not covered with tin, the dissolution becomes remarkable.
As a result, the projections 3 are easily broken, and when the interlayer insulating layer 5 is formed on the lower layer pattern 2 in this state, the anchor effect of the projections 3 formed on the lower layer pattern 2 is weak. Therefore, the effect of the adhesion between the lower layer pattern 2 and the interlayer insulating layer 5 becomes insufficient.

As described in detail above, according to the method of manufacturing a wiring board of the present embodiment, the lower layer pattern 2 is plated with tin substitution with a thickness of 0.10 to 0.13 μm. A wiring board in which the and the interlayer insulating layer 5 are firmly adhered can be obtained. Further, in the present embodiment, since the plating layer 4 is formed on the side surfaces of the projections 3 formed on the surface of the roughened lower layer pattern 2 in an uneven manner, the interlayer insulating layer 5 is hardly peeled off. So
There is provided a wiring board in which the lower layer pattern 2 and the interlayer insulating layer 5 are more firmly adhered.

The present embodiment is merely an example, and does not limit the present invention. Therefore, various modifications and improvements can be made without departing from the scope of the present invention.

[0024]

As is apparent from the above description, according to the present invention, there is provided a method of manufacturing a wiring board and a wiring board which provide sufficient adhesion between the surface of the conductive layer and the insulating layer.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a lower layer pattern is formed on a starting substrate.

FIG. 2 is a view showing a state where a lower layer pattern is roughened.

FIG. 3 is an enlarged view of a lower layer pattern subjected to tin displacement plating.

FIG. 4 is a diagram showing a state in which an interlayer insulating layer is laminated on a plated lower layer pattern.

FIG. 5 is a graph showing the results of measuring the occurrence of blistering when a reflow heat is applied to a wiring board subjected to tin displacement plating.

FIG. 6
It is the figure which expanded the lower layer pattern which laminated the interlayer insulation layer.

[Explanation of symbols]

 3 Protrusion 4 Plating layer 5 Interlayer insulating layer

Claims (3)

[Claims] 1. A method for manufacturing a wiring board, comprising laminating an insulating layer on a conductor layer, wherein the surface of the conductor layer is roughened, and the surface of the roughened conductor layer is plated with tin. And a method of manufacturing the wiring board, wherein the insulating layer is laminated on the conductor layer. 2. The method for manufacturing a wiring board according to claim 1, wherein the plating thickness in the tin displacement plating is 0.1%.
A method for manufacturing a wiring board, wherein the thickness is 0 to 0.13 μm. 3. A wiring board comprising an insulating layer laminated on a conductor layer, wherein the surface of the conductor layer is roughened and tin-plated to form an overhang. Characteristic wiring board.