JP3450626B2 - Electronic component mounting substrate and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting board for mounting an electronic component such as an IC by wire bonding or the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as an electronic component mounting substrate for mounting an electronic component such as an IC, as shown in FIG. 3, a ground pad 52b electrically connected by an internal wiring 60, Independent signal pad 52
a and a heat sink 62 for efficiently dissipating heat generated by driving the mounted electronic component, and the ground pad 52b and the heat sink 62 are not electrically connected by the internal wiring 60. A mounting board 50 is known.

The pad 52 (ground pad 52b and signal pad 52a) is a ceramic insulating substrate 51.
The metallized metal layer 53 made of tungsten provided on the nickel-boron alloy layer 5 formed thereon
5, and a nickel-phosphorus alloy layer 57 formed thereon,
And a gold layer 59 formed thereon.

On the other hand, the heat sink 62 is the insulating substrate 51.
Of these, a surface opposite to the surface on which the pad 52 is provided is brazed with a silver-copper alloy. This heat sink 62
Is a diffusion metal layer 65 provided so as to cover the heat sink base material 61 and in which nickel-boron and nickel-phosphorus are diffused.
And a nickel-phosphorus alloy layer 67 formed thereon,
And a gold layer 69 formed thereon.

As one method for manufacturing the above electronic component mounting board 50, the procedure shown in FIG. 4 can be considered. First, the insulating substrate 51 including the pad forming portion 52 ′ and the internal wiring 60 is prepared. This pad forming portion 52 '
Comprises a metallized metal layer 53 and a nickel-boron alloy layer 55 formed thereon. The heat sink base material 61 before brazing is plated with nickel-boron plating 65a, and then nickel-phosphorus plating 65a.
b, and then brazing to the insulating substrate 51 (about 850
(° C.), a heat sink forming portion 62 ′ is provided. After brazing, since the nickel-boron plating 65a and the nickel-phosphorus plating 65b diffuse with each other depending on the heating temperature at the time of brazing, a phosphorus-rich diffusion metal layer 65 is formed on the surface side. Then, the electroless nickel-phosphorus plating is applied to the substrate 50 'having the pad forming portion 52' and the heat sink forming portion 62 'in this manner.
Then, electroless gold plating is performed to obtain the electronic component mounting substrate 50.

[0006]

However, when the electronic component mounting board 50 is manufactured by the above method,
Pad forming portion 52 'and heat sink forming portion 6
When the electroless nickel-phosphorus plating is applied to the substrate 50 'having 2'and nickel-phosphorus is unidirectionally deposited only on the pad forming portion 52', and the heat sink forming portion 62 '.
In many cases nickel-phosphorus did not precipitate.

Thus, the heat sink forming portion 62 '
When nickel-phosphorus was not deposited on the surface, the gold layer 69 formed by the electroless plating in the subsequent step tended to be peeled off, and there was a possibility that it could not be actually used. Further, since the gold layer 69 is directly formed on the brazing material portion, there arises a problem that the corrosion resistance is lowered.

As a result, the heat sink 62 and the pad 52
There is a problem that the production efficiency is poor when the electronic component mounting substrate 50 which is electrically disconnected is manufactured. The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic component mounting substrate in which a heat sink and a pad are not electrically connected to each other and which can improve production efficiency. . Moreover, it aims at providing the manufacturing method.

[0009]

Means for Solving the Problems, Embodiments of the Invention, and Effects of the Invention In order to solve the above-mentioned problems, the electronic component mounting substrate of the present invention has a nickel-boron alloy layer with a palladium layer interposed between the nickel layers. A pad having a structure in which a phosphorus alloy layer is laminated and a gold layer is laminated thereon, and the pad is electrically unconnected, and palladium is formed on a metal layer made of a metal different from the nickel-boron alloy. And a heat sink having a structure in which a nickel-phosphorus alloy layer is laminated via a layer and a gold layer is laminated thereon.

In the present invention, the pads are provided on a substrate (for example, an insulating substrate such as ceramic or glass) and are electrically connected to each other by, for example, internal wiring or electrically independent. There is. In such a pad, for example, a metallized metal layer of tungsten, molybdenum, molybdenum-manganese, titanium or the like is formed on a ceramic insulating substrate, and a nickel-boron alloy layer is formed thereon.
A palladium layer, a nickel-phosphorus alloy layer, and a gold layer are laminated in this order.

Further, the heat sink has a function of efficiently dissipating the heat when the mounted electronic parts generate heat during driving. This heat sink is not connected to the pad by the internal wiring, and is electrically disconnected. The heat sink is, for example, copper-tungsten,
A metal layer made of a metal different from a nickel-boron alloy is provided around a heat sink base material such as copper-molybdenum, copper, or a copper / molybdenum / copper clad material, and a palladium layer, a nickel-phosphorus alloy layer, thereon. The gold layers are stacked in this order.

Here, as the metal layer made of a metal different from the nickel-boron alloy, for example, first, nickel-
It may be a diffusion metal layer in which both plating layers are diffused by the heat applied when a boron alloy is plated, then a nickel-phosphorus alloy is plated, and then brazing is performed at 800 to 900 ° C., for example. In such a diffusion metal layer, phosphorus is richly distributed on the surface side. When such a diffusion metal layer is used, a brazing material such as a silver-copper alloy does not rise to the heat sink substrate during brazing, which is preferable.

In the present invention, the palladium layer includes not only an ordinary layer having a substantially uniform spread with respect to the base, but also a case where the palladium layer is substantially uniformly distributed in a nucleus (dot shape) with respect to the base. To form such a palladium layer, the object to be treated may be immersed in an aqueous solution of a palladium compound.

The aqueous solution of the palladium compound is, for example, an aqueous solution of palladium chloride, palladium sulfate, palladium nitrate or the like (as the metal palladium, for example, 50 to 150).
It is preferable to use those containing ppm). Acids (for example, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid) for preventing hydrolysis of the palladium compound may be added to this aqueous solution, or an alkali salt (for example, an inorganic acid such as a dissolution accelerator, for example,
Sodium chloride, sodium sulfate, sodium nitrate or other sodium salt) may be added, and if necessary, a palladium compound stabilizer (eg, ethylenediamine, sulfamic acid, nitriloacetic acid, or other complexing agent),
Surfactants for giving a wetting effect (for example, nonionic surfactants such as polyoxyethylene alkylphenyl ether and polyoxyethylene alkyl ether), reducing agents for improving the adhesion of palladium (for example, dimethylamine borane, ascorbine) Acid, sodium hypophosphite, formaldehyde, etc.) may be added.

The method of treating the palladium compound with an aqueous solution is not particularly limited, but usually, it is degreased according to a conventional method and, if necessary, activated with an acid or an alkali,
The object to be treated may be immersed in the aqueous solution. The treatment conditions are generally a temperature of about 15 to 40 ° C. and a soaking time of about 30 to 240 seconds.

After forming the palladium layer as described above, the nickel-phosphorus alloy layer is formed by electroless plating under known conditions. Conventionally, a pad-forming portion coated with a nickel-boron alloy and a heat sink-forming portion coated with a different metal (for example, the diffusion metal layer described above) are simultaneously coated with a nickel-phosphorus alloy by electroless plating. Although there was a problem that the nickel-phosphorus alloy was deposited only on the pad forming portion even when trying to cover it, this time, by forming the palladium layer in advance, the nickel-phosphorus alloy is deposited on both the pad forming portion and the heat sink forming portion. The alloy began to precipitate.

The reason for this is not clear, but nickel-
A potential difference is generated between the pad forming portion coated with the boron alloy and the heat sink forming portion coated with the metal different from the nickel-boron alloy (for example, the diffusion metal layer described above), which is a cause. Electroless nickel-
In the phosphorus plating, the nickel-phosphorus alloy tended to be deposited only on the pad forming portion, but this time, it is considered that the potential difference was eliminated by coating both with the palladium layer.

As described above, according to the method of manufacturing the electronic component mounting substrate of the present invention, the pad forming portion coated with the nickel-boron alloy and the pad forming portion are electrically formed on the same substrate. When a nickel-phosphorus alloy layer is formed by electroless plating on a heat sink forming portion that is not electrically connected and is covered with a metal different from the nickel-boron alloy, which portion does not exist? Also in this case, there is no occurrence of plating defects such as non-plating, and the yield is improved and the production efficiency is improved. The electronic component mounting board of the present invention has a structure suitable for mass production.

[0019]

【Example】

[Embodiment 1] FIG. 1 is a schematic diagram showing a schematic configuration of the present embodiment. The electronic component mounting substrate 10 includes an insulating substrate 11 made of alumina ceramic, a pad 12, and a heat sink 22.
Is equipped with.

The pad 12 comprises a metallized metal layer 13 made of tungsten, a palladium layer 14, a nickel-boron alloy layer 15, a palladium layer 16, a nickel-phosphorus alloy layer 17, and a gold layer 19 provided on the insulating substrate 11. The layers are stacked in this order. There are two types of pads 12, a ground pad 12b that is electrically connected by the internal wiring 20 and a signal pad 12a that is electrically independent.

In the heat sink 22, a copper-tungsten heat sink base material 21 covered with a diffusion metal layer 25 is brazed onto the insulating substrate 11, and a palladium layer 26, a nickel-phosphorus alloy layer 27, and a gold layer are formed thereon. 29 are stacked in this order. The electronic component mounting substrate 10
The manufacturing method will be described with reference to FIG.

First, an organic solvent or the like is added to and mixed with a predetermined alumina raw material powder to form a slurry, which is made into a ceramic green sheet by adopting a doctor blade method or the like, and then a conductor paste made of tungsten powder or the like is prepared. Using this, a ceramic green sheet was screen-printed, and then, although not shown, an appropriate number of these were laminated, pressure-bonded, and simultaneously fired at 1600 ° C. As a result, the metallized metal layer 13 was formed on the insulating substrate 11, and the internal wiring 20 was integrally formed in the insulating substrate 11.

Subsequently, it was immersed in an aqueous solution containing a palladium compound as a main component (Pd-5 (trade name) manufactured by Nippon Kojundo Chemical Co., Ltd.) at 60 ° C. for 60 seconds. As a result, a palladium layer 14 (actually, it does not have a substantially uniform spread on the underlayer, but is distributed substantially uniformly in a dot shape) was formed. In addition, Pd-5 contains palladium chloride as a palladium compound, and is 80 p as metallic palladium.
including pm.

Next, an electroless plating solution containing nickel sulfate and dimethylamine borane as a reducing agent (BN-1500 (trade name) manufactured by Dip-Reel) was used to obtain a solution temperature of 65.
The nickel-boron alloy layer 15 having a thickness of 1.5 μm is plated at a temperature of 6.5 ° C. and a plating time of 15 minutes.
It was formed by deposition and then sintered. The reason why the nickel-boron alloy layer 15 is provided in this manner is that the nickel-boron alloy layer 15 is deposited on the rough base with a uniform thickness without forming pinholes (small holes) or voids (small voids).

As a result, the initial substrate 6 was obtained (see FIG. 2). Of the initial substrate 6, the metallized metal layer 13,
The portion provided with the palladium layer 14 and the nickel-boron alloy layer 15 will be referred to as a pad forming portion 12 '.
On the other hand, the heat sink side was manufactured as follows. That is, the heat sink base material 21 made of a copper-tungsten alloy was immersed in the above-mentioned Pd-5 (trade name) at 60 ° C. for 60 seconds.
As a result, a palladium layer 23 (actually, it does not have a substantially uniform spread on the base, but is distributed substantially uniformly in a dot shape) was formed.

Subsequently, the above-mentioned BN-1500 (trade name)
Plating is performed under the conditions of a liquid temperature of 65 ° C., a pH of 6.5, and a plating time of 6 minutes to obtain a nickel-boron alloy layer 25.
A was deposited to a thickness of 0.6 μm, and thereafter sintering was performed. The nickel-boron alloy layer 25a is provided in order to deposit the nickel-boron alloy layer 25a with a uniform thickness on the rough surface of the base without forming pinholes (small holes) or voids (small voids).

Subsequently, the nickel-boron alloy layer 25
On a, an electroless plating solution (Nimden 78S (trade name) manufactured by Uemura Kogyo Co., Ltd.) was used, and the solution temperature was 90 ° C. and the pH was 6.
0, the plating time is 10 minutes, plating is performed to form a nickel-phosphorus alloy layer 25b with a thickness of 3.0 μm,
After that, sintering was performed. Thereby, the initial heat sink 9 was obtained (see FIG. 2). The nickel-phosphorus alloy layer 25b is provided to prevent a phenomenon (so-called brazing flow) in which the brazing material (for example, silver-copper alloy) rises toward the initial heat sink 9 during brazing. .

Then, the initial heat sink 9 was brazed to the insulating substrate 11 at about 800 ° C. using a silver-copper alloy as a brazing material. Heat sink forming part 2 after brazing
2 '. The heat sink forming portion 22 'has a diffusion metal layer 25 formed by the nickel-boron alloy layer 25a and the nickel-phosphorus alloy layer 25b diffusing each other by the heat during brazing. The diffusion metal layer 25 has a rich phosphorus distribution on the surface. The heat sink forming portion 22 'is not electrically connected to the pad forming portion 12' by the internal wiring 20.

The pad-forming portion 1 thus produced
The following palladium treatment and electroless nickel-phosphorus plating were applied to the first intermediate substrate 7 having 2'and the heat sink forming portion 22 '. -Palladium treatment The above Pd-5 (trade name) was immersed for 60 seconds at 60 ° C.
As a result, the palladium layers 16 and 26 (actually, the underlying layer does not have a substantially uniform spread but is distributed substantially uniformly in a dot shape) are formed.

On the electroless nickel-phosphorus plated palladium layers 16 and 26, the above-mentioned Nimden 78S.
(Trade name) is used to perform plating under the conditions of a liquid temperature of 90 ° C., pH 6.0, and a plating time of 10 minutes to form nickel-phosphorus alloy layers 17 and 27 with a thickness of 3.0 μm, and thereafter sintering. I went. Here, nickel-phosphorus alloy layer 1
7 is provided to strengthen the adhesion between the gold layer 19 to be formed later and the nickel-boron alloy layer 15 as the lower layer. Further, the nickel-phosphorus alloy layer 27 is provided
This is because the adhesion between the gold layer 29 and the diffusion metal layer 25, which will be formed later, is strengthened and at the same time, the brazing material silver or copper is prevented from seeping out to the surface of the gold layer 29.

As a result, the second intermediate substrate 8 before electroless gold plating was obtained. Then, this second intermediate substrate 8
, Using a plating solution for substitutional electroless gold plating (Atomex (trade name) manufactured by NE Chemcat Co., Ltd.) under the conditions of a liquid temperature of 85 ° C., pH 6.0, and a plating time of 3 minutes. The thin gold layer to a thickness of 0.01-0.1
μm deposited. Subsequently, using an electroless plating solution (OPC Muden Gold 25 (trade name) manufactured by Okuno Chemical Industries Co., Ltd.) containing sodium borohydride as a reducing agent, the solution temperature was 73 ° C., the pH was 13.5, and the plating time was 30. Plating was performed under the condition of minutes, and a thick gold layer was formed to a thickness of 2.0 μm. Thereby, the gold layers 19 and 29 (see FIG. 1) were formed, and the electronic component mounting substrate 10 was obtained.

The electronic component mounting substrate 10 obtained in this way is obtained by the electroless nickel-phosphorus plating described above.
Nickel-phosphorus was deposited on both the pad forming portion and the heat sink forming portion, and plating defects such as non-plating did not occur even in mass production, and the effect of high production efficiency was obtained.

[Test Examples 1 to 3] As Test Examples 1 to 3, 100 pieces of substrates each having a pad forming portion and a heat sink forming portion, which were produced in the same manner as in the above-described Example 1, were prepared for each test example. Then, after forming a palladium layer under predetermined conditions, plating is performed using the above-mentioned Nimden 78S (trade name) at a liquid temperature of 90 ° C., a pH of 6.0, and a plating time of 10 minutes to form a thick nickel-phosphorus alloy layer. 3.0 μm
The number of adhered nickel-phosphorus adhered states was investigated out of the whole (100 pieces). The results are shown in Table 1 below. The predetermined palladium treatment was carried out as follows in Test Examples 1 to 3. Test Example 1 Palladium treatment was not performed. Test Example 2 Using Pd-5 (trade name) described above, liquid temperature 60 ° C., pH
Palladium treatment was performed under the conditions of 2.5 and plating time of 30 seconds. Test Example 3 Using Pd-5 (trade name) described above, liquid temperature 60 ° C., pH
The palladium treatment was performed under the conditions of 2.5 and plating time of 1 minute.

[0034]

[Table 1]

As is clear from Table 1 above, nickel-
If the pad forming part covered with the boron alloy layer and the heat sink forming part covered with the diffusion metal layer are present on the same substrate, if palladium layers are formed in both parts in advance, then When a nickel-phosphorus alloy layer is formed on both parts by electroless plating, the occurrence of plating defects such as non-plating tends to be suppressed, and particularly Test Example 3
It was found that under the conditions of 1), the occurrence of plating defects was extremely effectively suppressed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an electronic component mounting board according to a first embodiment.

FIG. 2 is a manufacturing process diagram of the electronic component mounting substrate of the first embodiment.

FIG. 3 is a schematic diagram showing a schematic configuration of a conventional electronic component mounting board.

FIG. 4 is a manufacturing process diagram of the electronic component mounting substrate of the first embodiment.

[Explanation of symbols]

6 ... Initial substrate, 7 ... First intermediate substrate, 8 ... Second intermediate substrate, 9 ... Initial heat sink, 10 ... Electronic component mounting substrate, 11 ... Insulating substrate, 12 ... Pad, 12 '... Pad forming portion, 12a ... Ground pad, 12b ... Signal pad, 13
... Metalized metal layer, 14 ... Palladium layer, 1
5 ... Nickel-boron alloy layer, 16 ... Palladium layer, 17 ... Nickel-phosphorus alloy layer, 19 ... Gold layer, 20 ... Internal wiring, 21 ... Heat sink base material, 22 ... Heat sink, 22 '... Heat sink forming part, 23 ... Palladium layer, 25 ... Diffusion metal layer, 25a ... Nickel-boron alloy layer, 25
b ... Nickel-phosphorus alloy layer, 26 ... Palladium layer, 27 ... Nickel-phosphorus alloy layer, 29 ... Gold layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 23/12 H01L 23/36 H01L 23/02 H01L 23/08

Claims (3)

(57) [Claims] 1. A pad having a structure in which a nickel-phosphorus alloy layer is laminated on a nickel-boron alloy layer via a palladium layer, and a gold layer is laminated thereon, and the pad is electrically non-conductive. A heat sink having a structure in which a nickel-phosphorus alloy layer is laminated on a metal layer made of a metal different from a nickel-boron alloy via a palladium layer, and a gold layer is laminated thereon. A board for mounting electronic parts, characterized by: 2. In the heat sink, nickel-
The metal layer made of a metal different from the boron alloy layer is a diffusion metal layer in which the nickel-boron alloy layer and the nickel-phosphorus alloy layer are diffused and phosphorus is richly distributed on the palladium layer side. The electronic component mounting substrate according to claim 1. 3. The method for manufacturing the electronic component mounting substrate according to claim 1, wherein the pad forming portion having a nickel-boron alloy layer as a surface layer and the pad forming portion are electrically non-conductive. For a substrate provided with a heat sink forming portion having a metal layer made of a metal different from nickel-boron alloy for connection, a palladium compound is applied to both the pad forming portion and the heat sink forming portion. A palladium layer is formed by treating with an aqueous solution containing a reducing agent and then with an aqueous solution containing a reducing agent, then a nickel-phosphorus alloy layer is formed by electroless plating, and then a gold layer is formed by electroless plating. A method for manufacturing an electronic component mounting substrate.