JPH10168579A - Wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which a gold plated layer is uniformly formed on a nickel-phosphorus plated layer, and brister and peeling do not occur between both plated layers. SOLUTION: A package main body 1 for electronic parts is equipped with an insulating substrate 2 consisting of alumina ceramic, a metallized metallic layer 3, a nickel-boron plated layer 4, a nickel-phosphorus plated layer 5 and a gold plated layer 6, and is so constituted that each layer is piled up in this order. At this time, the nickel-phosphorus plated layer 5 contains 5 to 10% phosphorus by weight. Thus, peeling and blister do not occur between the nickel- phosphorus plated layer 5 and the gold plated layer 6, thereby the yield is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board on which a semiconductor integrated circuit element (IC) is mounted, and a wiring board which constitutes a package body for an electronic part for housing electronic parts such as a semiconductor integrated circuit element.

[0002]

2. Description of the Related Art Conventionally, when fabricating a wiring board such as an IC package, a metallized metal layer made of tungsten is formed on a ceramic insulating substrate as a material as disclosed in, for example, Japanese Patent Publication No. 6-84546. Then, a nickel-boron (Ni-B) plating layer is formed on the surface of the metallized metal layer by reduction type electroless plating, and nickel-phosphorus (Ni
-P) A plating layer was formed, and a gold (Au) plating layer was formed thereon by electroless plating.

Here, the nickel-boron plating layer is useful in that it is applied to a uniform thickness without forming pinholes (small holes) or voids (small voids) on the rough metallized metal layer. Yes, and the nickel-phosphorus plating layer is
It is useful in that it plays a role in strengthening the adhesion between the surface gold plating layer and the lower nickel-boron plating layer.

[0004]

When a nickel-phosphorous plating layer is subjected to reduction-type electroless plating to form a gold plating layer having a predetermined thickness, gold is successfully deposited on the nickel-phosphorous plating layer. May not. Here, reduction type electroless plating refers to electroless plating in which a metal film is formed using a plating solution containing a reducing agent.

In order to form a gold plating layer having a predetermined thickness, a thin gold plating layer is first formed on a nickel-phosphorous plating layer by substitutional electroless plating, and then a reduction type electroless plating is performed. Thus, a gold plating layer having a predetermined thickness is formed. Here, substitutional electroless plating is electroless plating in which a metal film is formed by utilizing the difference in ionization tendency. In the case of gold plating, the metal (nickel here) on the surface of the object to be plated is reduced. It melts and becomes metal ions and electrons, and the gold ions receive and precipitate the electrons.

However, in the conventional wiring board for IC packages, the nickel-phosphorous plating layer and the gold plating layer are not sufficiently adhered to each other, and blisters and peeling often occur between the two layers, resulting in poor yield. There was a problem. The present invention has been made in view of the above problems, and nickel-
An object of the present invention is to provide a wiring board in which a gold plating layer is uniformly formed on a phosphorous plating layer and free of blisters and peeling between the two layers, and to provide a manufacturing method thereof.

[0007]

Means for Solving the Problems, Embodiments of the Invention and Effects of the Invention In order to solve the above problems, the wiring board according to claim 1 comprises a nickel-phosphorous plating layer and a nickel-phosphorous plating layer.
A gold plating layer uniformly formed on the surface of the phosphorous plating layer, and a property that no blistering or peeling occurs between the nickel-phosphorous plating layer and the gold plating layer after being left at 450 ° C. for 5 minutes. It is characterized by having.

In this wiring board, it is sufficient that a gold plating layer is formed on the surface of the nickel-phosphorus plating layer. For example, another metal layer (for example, tungsten, molybdenum, molybdenum) is formed under the nickel-phosphorus plating layer. -A metallized metal layer such as a manganese alloy or a nickel-boron plating layer), or a nickel-phosphorous plating layer is directly formed on an insulating substrate which is a material without such a lower layer. You may.

This wiring board was left at 450 ° C. for 5 minutes to examine its properties. The condition of 450 ° C. for 5 minutes is an acceleration for judging whether or not it can be actually used for a long period of time. Strict conditions were selected for the test. Therefore, when blisters and peeling do not occur between both layers under this condition, the blisters and peeling do not occur even in actual use, and the product value is sufficiently recognized.

Therefore, according to the wiring board having the characteristics of the present invention, the effects of improving the yield and greatly increasing the productivity can be obtained. In the present invention, as described in claim 2, the nickel-phosphorus plating layer has a phosphorus content of 5%.
It is preferably from 10 to 10% by weight. In this case, a gold plating layer is uniformly formed on the nickel-phosphorus plating layer,
In addition, there is an effect that the yield is remarkably improved without swelling or peeling between both layers.

The method for quantitatively analyzing the phosphorus content is not particularly limited. For example, it is preferable to determine the content by an energy dispersive X-ray analyzer. here,
If the phosphorus content exceeds 10% by weight, the corrosion resistance of the nickel-phosphorous plating layer increases. For example, when forming the gold plating layer by substitutional electroless plating as in claim 3, the nickel-phosphorus plating Nickel is less likely to elute from the layer, and as a result, gold tends to be less likely to precipitate, which is not preferred.

On the other hand, when the phosphorus content is less than 5% by weight, for example, when the gold plating layer is formed by substitution type electroless plating, the interface between the nickel-phosphorus plating layer and the gold plating layer is determined. In this case, the adhesion between the two layers tends to be deteriorated due to, for example, the formation of a nickel oxide layer, which is not preferable.

As a method of manufacturing the above wiring board,
As described in claim 4, the material (for example, ceramic,
Insulating substrate such as glass, metallized layer or nickel
A step of forming a nickel-phosphorus plating layer on a plating layer such as a boron plating layer by reduction type electroless plating so that the phosphorus content is 5 to 10% by weight;
Forming a gold plating layer on the surface of the phosphorus plating layer by substitution type electroless plating. In this case, the substitution-type electroless gold plating stops the reaction when the underlying metal (that is, the nickel-phosphorus plating layer) is completely covered with gold, so that the film thickness of the gold plating layer becomes thin (for example, 0.1 mm). 01-0.1 μm). Usually, a gold plating layer formed by reduction type electroless plating is formed on the gold plating layer formed by substitutional electroless plating in order to further increase the thickness of the gold plating layer. Thereby, the overall thickness of the gold plating layer is, for example,> 0.3 μm.

As the plating solution for depositing and forming gold by substitutional electroless plating, a conventionally known plating solution can be used. For example, an alkali cyanide stabilizer or the like is added to a soluble gold salt. Plating solution or the like can be used.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The embodiments of the present invention are not limited to the following examples at all, and it goes without saying that various embodiments can be adopted as long as they belong to the technical scope of the present invention. Embodiment 1 An electronic component package body 1 includes an insulating substrate 2 made of alumina ceramic, a metallized metal layer 3,
It has a nickel-boron plating layer 4, a nickel-phosphorus plating layer 5, and a gold plating layer 6, and each layer is formed so as to be stacked in this order.

The electronic component package body 1 was manufactured by the following procedure. That is, a predetermined alumina raw material powder is mixed with an organic solvent and the like to form a slurry, which is formed into a ceramic green sheet by employing a doctor blade method or the like, and thereafter, a ceramic is formed using a conductor paste made of tungsten powder or the like. Screen printing was performed on the green sheet, and then, though not shown, an appropriate number of these were laminated, pressed, and fired simultaneously at 1600 ° C. Thereby, the metallized metal layer 3 was integrally formed on the insulating substrate 2.

Then, on this metallized metal layer 3,
Using an electroless plating solution (Top Chemialloy B-1 (trade name) manufactured by Okuno Pharmaceutical Co., Ltd.) containing nickel sulfate and DMAB dimethylamine borane as a reducing agent, a solution temperature of 65 ° C.
Plating was performed under conditions of pH 6.7 and plating time of 15 minutes, a nickel-boron plating layer 4 was applied and formed to a thickness of 1.2 μm, and then heated to braze pin terminals (not shown) with silver brazing.

Next, the nickel-boron plating layer 4
The solution temperature was 90 ° C. and the pH was adjusted using an electroless plating solution (Blue Schumer (trade name) manufactured by Nippon Kanigen Co., Ltd.) containing nickel sulfate and sodium hypophosphite as reducing agents.
Plating under the condition of 6.0, plating time 10 minutes,
A nickel-phosphorous plating layer 5 was formed with a thickness of 3.0 μm, and then the nickel-phosphorous plating layer 5 was sintered.

Subsequently, using a plating solution for substitution type electroless gold plating (Atomex (trade name) manufactured by NE Chemcat Co., Ltd.), the solution temperature was 85 ° C., the pH was 6.0, and the plating time was 3 minutes. The first gold plating layer 6a corresponding to the lower layer of the gold plating layer 6 was formed to a thickness of 0.01
０．１0.1 μm.

Finally, an electroless plating solution containing sodium borohydride as a reducing agent (OPC manufactured by Okuno Pharmaceutical Co., Ltd.)
Liquid temperature 73 (Mudden Gold 25 (trade name))
Plating was performed under the conditions of ° C, a pH of 13.5, and a plating time of 30 minutes, and a second gold plating layer 6b corresponding to the upper layer of the gold plating layer 6 was adhered and formed to a thickness of 2.0 µm.

Thus, the electronic component package body 1 having the structure shown in FIG. 1 was manufactured. [Comparative Examples 1 to 3] In Comparative Examples 1 to 3, a nickel-phosphorous plating layer was formed using a plating solution shown in Table 1 below instead of the plating solution for the reduction type electroless nickel-phosphorous plating of Example 1 described above. An electronic component package body having the same structure as that of FIG. 1 was produced in the same manner as in Example 1 except that it was adhered.

[0022]

[Table 1]

Test Example As described above, test pieces (30 × 50 mm) of Example 1 and Comparative Examples 1 to 3 were each 100
Pieces were manufactured, and the following inspection and analysis were performed on these pieces. Regarding Presence or Absence of No Plating No plating refers to a state in which a gold plating layer is not adhered to part or all of a nickel-phosphorus plating layer. In the inspection for no plating, if the underlying nickel-phosphorous plating layer was visible when the test piece was viewed from above or visually from above with a magnifying glass of 20 times, it was determined that no plating had occurred.

About the presence or absence of peeling or blistering After the test pieces of each test example were left at 450 ° C. for 5 minutes, the presence or absence of peeling or blistering between the nickel-phosphorus plating layer and the gold plating layer was determined. Inspected. Here, peeling refers to a state in which the gold plating layer is separated from the nickel-phosphorous plating layer so as to be turned up and the underlying nickel-phosphorous plating layer is exposed. In the test for peeling, it was judged that peeling occurred when the test piece was visible from above or visually from above with a magnifying glass of 20 times.

The blister means a substantially circular swelling locally generated between the gold plating layer and the nickel-phosphorus plating layer. In the inspection of swelling, when the test piece was visually observed or viewed from above with a magnifying glass 20 times, it was determined that blisters having an area of ５０50 μm or more swelled.

Regarding phosphorus content In each of Example 1 and Comparative Examples 1 to 3, nickel-
When the phosphorus plating layer 5 was formed by adhesion, a quantitative analysis of the phosphorus content of the nickel-phosphorus plating layer 5 was performed. This quantitative analysis was carried out using a model: JEOL (JEOL) manufactured by JSM-8.
20, detector: using an energy dispersive X-ray analyzer manufactured by Tray Core Northern Co., Ltd., an acceleration voltage of 20 kV,
The analysis was performed under the condition of an analysis magnification of 3700 times (30 × 23 μm).

The results of the above inspection and analysis are shown in Table 2 below.

[0028]

[Table 2]

In Table 2, the typical phosphorus content is 1
According to quantitative analysis performed several times, it was within the range of 2 to 5% by weight in Test Example 2, 5 to 10% by weight in Test Example 3, and 10 to 13% by weight in Test Example 4. Was. As is clear from Table 2, Test Examples 1 and 2 (Comparative Examples 1 and 2)
Although no plating was not generated, the yield was poor because of the occurrence of peeling and swelling, and the yield was low in Test Example 4 (Comparative Example 3) because of the high incidence of plating but no occurrence of peeling and swelling. bad. On the other hand, in Test Example 3 (Example 1), neither peeling nor blistering nor plating occurred. For this reason, the effect that the yield is good and the productivity is high in mass production can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of an electronic component package body according to a first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic component package main body, 2 ... Insulating board, 3 ... Metallized metal layer, 4 ... Nickel-boron plating layer, 5 ... Nickel-phosphorus plating layer, 6 ...
..Gold plating layer, 6a ... first gold plating layer, 6b
-Second gold plating layer.

Claims (4)

[Claims] A nickel-phosphorous plating layer; and a gold plating layer uniformly formed on the surface of the nickel-phosphorous plating layer. A wiring board having a property that blisters and peeling do not occur between the wiring board and a gold plating layer. 2. The wiring board according to claim 1, wherein the nickel-phosphorus plating layer has a phosphorus content of 5 to 10% by weight. 3. The wiring board according to claim 1, wherein a portion of the gold plating layer that contacts the nickel-phosphorus plating layer is formed by substitution type electroless plating. 4. A step of forming a nickel-phosphorus plating layer on a material by reduction type electroless plating so that the phosphorus content is 5 to 10% by weight; Forming a thin gold-plated layer by electrolytic plating.