JPH0693538B2 - Ceramic printed circuit board and method for manufacturing the same - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic wiring circuit board and a method for manufacturing the same, and more specifically, it is used as a semiconductor mounting wiring circuit board or the like, and is a terminal for external connection to a wiring circuit. The present invention relates to a ceramic wiring circuit board used by brazing an external metal member such as a pin and a method for manufacturing such a ceramic wiring circuit board.

[Conventional technology]

Conventionally, methods such as a telefunken method, an active metal method, and a metal paste method have been adopted as a method for manufacturing a ceramic wiring circuit board. Further, in recent years, a method of directly metalizing copper on a ceramic insulating substrate has been proposed as a conductor metal layer forming a wiring circuit. Since copper is a base metal having excellent conductivity and migration resistance, it is possible to achieve fine wiring and cost reduction, and various manufacturing methods have been studied.

On the other hand, when the ceramic wiring circuit board is used as a semiconductor mounting board in a semiconductor package, it is necessary to bond terminal pins for electrically and mechanically connecting to an external circuit to the wiring circuit of the ceramic wiring circuit board. There is. A brazing method using a silver brazing material or the like is adopted for joining the terminal pin to the wiring circuit. In addition to the above-mentioned semiconductor mounting substrate, the ceramic printed circuit board may have to be joined by brazing metal members such as terminal pins in various applications.

[Problems to be Solved by the Invention]

However, the above-mentioned ceramic wiring circuit board having a wiring circuit made of a copper layer has many problems when brazing terminal pins and the like for use.

That is, when attempting to bond a terminal pin to a copper layer formed on a ceramic insulating substrate by a copper direct metallization method using a silver brazing material, the copper contained in the brazing material is eaten by the silver. There is. Therefore, conventionally, the surface of the copper layer is coated with nickel, and the nickel layer is used as a barrier layer against silver. By increasing the thickness of this nickel barrier layer, the diffusion of silver can be effectively prevented and the copper layer can be protected. However, when the nickel barrier layer becomes thicker, there is a problem that the internal stress increases and the adhesion between the ceramic insulating substrate and the copper layer decreases. Therefore, there is a limit to the increase in the thickness of the nickel barrier layer, and it was not possible to exhibit sufficient barrier properties. Further, there is a problem that the heating in the brazing process causes diffusion of copper and nickel, and the barrier effect of the nickel barrier layer against the diffusion of silver is substantially reduced.

In order to improve the above problems, it is necessary to strictly control the processing conditions such as the thickness and film quality of the nickel layer, the amount of silver brazing material, the brazing temperature, and the time. It is very difficult to strictly control the conditions, which causes the low yield of the brazing process.

Then, the subject of this invention is the ceramic wiring circuit board which joins external metal members, such as a terminal pin, by brazing,
The brazing process does not require the strict process control as described above, can easily and surely perform brazing, and provides a ceramic wiring circuit board with high brazing joint strength, and at the same time, such a ceramic wiring board. The object is to provide a method for efficiently manufacturing.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the present invention, the ceramic wiring circuit board according to claim 1 is a ceramic wiring circuit board which is used by brazing an external metal member to a wiring circuit, and is a conductor metal constituting a wiring circuit. Among the layers, at least the conductor metal layer forming the wiring circuit at the brazing point is a nickel layer directly formed on the ceramic insulating substrate, and the conductor forming the wiring circuit portion other than the wiring circuit portion made of this nickel layer. The metal layer is a copper layer.

As the ceramic insulating substrate, one made of various ceramics such as alumina, aluminum nitride, and other oxide-based, nitride-based, and carbide-based ceramics is used, as in a normal wiring board.

The method for forming the conductor metal layer on the ceramic wiring circuit board is a so-called dry plating method such as a sputtering method or an ion plating method, or a wet plating method such as an electroless plating method or an electrolytic plating method, and other ordinary wiring boards. A film forming means can be adopted as in As the circuit forming means of the wiring circuit, the circuit forming means employed in the usual wiring board manufacturing, such as the subtractive method, the additive method, and the semi-additive method, are used.

Although the nickel layer is formed at least in the wiring circuit at a portion to be brazed, a portion of the wiring circuit other than the brazing portion can be formed of a nickel layer as necessary. As a material of the nickel layer, in addition to pure nickel, an alloy containing nickel as a main component, which is not eroded by the brazing material and has a melting point higher than the brazing temperature, can be used. Specifically, Ni-P
(P content is about 3%) and Ni-B (B content is about 1%).

The copper layer is formed in a portion of the wiring circuit other than the portion where the nickel layer is formed. Therefore, when the wiring circuit is formed at least in the brazing part with the nickel layer and is formed only with the copper layer except the brazing part, or with both the copper layer and the nickel layer. There is. The copper layer and the nickel layer can be formed by overlapping a part of one conductor metal layer with the other conductor metal layer at a place where electrical connection is required. In forming the nickel layer and the copper layer, either conductor metal layer may be formed first.

An external metal member is joined to the ceramic printed circuit board according to the present invention by brazing. Examples of the external metal member include a terminal pin for a semiconductor package and others.
In a normal printed circuit board, various metal parts used for electrical connection or mechanical connection can be used. As for the type of brazing material used for brazing, the brazing treatment conditions, etc., the brazing method used in the ordinary wiring board manufacturing field can be applied. Since the nickel layer at the brazed portion has lower conductivity than the copper layer, it is preferable to use a highly conductive brazing material such as silver brazing material as the brazing material because the conductivity can be improved.

A method of manufacturing a ceramic wiring circuit board according to claim 2 is the method of manufacturing a ceramic wiring circuit board according to claim 1, wherein the wiring circuit portion is formed of a conductor metal layer of either one of a nickel layer and a copper layer. Is formed, the entire surface of the conductor metal layer is covered with a corrosion-resistant alloy layer, and the wiring circuit portion made of the remaining conductor metal layer is formed by etching.

The step of forming the wiring circuit portion formed of the conductor metal layer, which is previously formed, is performed in exactly the same manner as the circuit forming method for a normal wiring board. The corrosion-resistant alloy layer formed on the surface of the conductor metal layer protects the conductor metal layer before the formation of the wiring circuit portion composed of the remaining conductor metal layer in a later step. As a material of the above, a material that is not corroded by an etching solution or the like used in a subsequent circuit forming process is used.
Specifically, for example, P may be 5% or more, preferably
Nickel-based alloys such as Ni-P alloys and Ni-WP alloys containing 10% or more can be used. As a method for forming the corrosion-resistant alloy layer, an ordinary film forming means such as an electroless plating method can be adopted. The corrosion-resistant alloy layer is formed so as to cover the entire top surface and side surfaces of the conductor metal layer.

As a method of forming a wiring circuit portion composed of the remaining conductor metal layer after the corrosion-resistant alloy layer is formed, a usual circuit forming means can be arbitrarily applied. At this time, since the wiring circuit portion formed of the conductor metal layer formed earlier is protected by the corrosion-resistant alloy layer, the wiring circuit portion previously formed should not be completely covered with the etching resist or the previous conductor metal layer should be attacked. It is not necessary to use a different processing solution.

[Action]

According to the first aspect of the present invention, the nickel layer is directly formed on the surface of the insulating substrate, which is the brazed portion, in the wiring circuit. Therefore, like the conventional wiring board, the copper layer at the brazed portion is formed. Does not cause the problem of being eaten by silver. Further, unlike the case where the nickel barrier layer is formed on the copper layer at the brazing point, the problem that the barrier effect is lowered due to the diffusion of the copper layer and the nickel barrier layer does not occur. Since most of the wiring circuits other than the brazed parts that are the signal circuit section have a copper layer excellent as a circuit material, fine wiring and conductivity It is possible to sufficiently satisfy the requirements such as performance.

According to the second aspect of the present invention, it is possible to efficiently manufacture the ceramic printed circuit board according to the first aspect, which includes a wiring circuit including two kinds of conductor metal layers, that is, a nickel layer and a copper layer. That is, in order to form a wiring circuit composed of two kinds of conductor metal layers, a first step of forming a wiring circuit portion (A) composed of one conductor metal layer and a wiring circuit portion composed of the other conductor metal ( The second step of forming B) is sequentially performed. However, in the present invention, the second step is performed while the wiring circuit portion (A) formed in the first step is covered with the corrosion-resistant alloy layer. It is possible to reliably prevent the etching treatment performed in the second step from invading or adversely affecting the conductor metal layer of the wiring circuit portion (A).

In particular, when the etching resist layer is formed in order to pattern the wiring circuit portion (B) in the second step, the wiring circuit portion (A) formed in the first step is covered with the corrosion-resistant alloy layer. Therefore, it is not necessary to form the etching resist, and the step of forming the etching resist layer in the second step can be simplified.

Moreover, since the wiring circuit portion (A) formed in the first step is formed in a convex shape on the surface of the flat insulating substrate, the etching resist forming means by ordinary printing coating or the like
Even if the upper surface of the wiring circuit portion (A) is covered with the etching resist, the etching resist cannot be formed on the side surface of the wiring circuit portion (A). If the corrosion resistant alloy layer is not formed and the side surface of the wiring circuit portion (A) is directly exposed,
If the etching in the second step is performed, the side surface of the wiring circuit portion (A) is etched, causing a problem of so-called side etching. However, in the method of the present invention, since the corrosion-resistant alloy layer is formed also on the side surface of the wiring circuit portion (A), even if the etching resist is not formed on this portion, the conductor metal layer of the wiring circuit portion (A) is formed. There is no need to worry about etching.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a method of manufacturing a ceramic printed circuit board and a method of brazing an external metal member in order of steps.

As shown in step (a), a through hole 11 is formed in a ceramic insulating substrate 10 such as an alumina substrate, and then a nickel layer 20 serving as a first conductor metal layer is formed to form a predetermined wiring circuit. Form in a pattern. In this embodiment, since the terminal pin which serves as an external metal member is brazed at the through hole hole 11, the nickel layer 20 is formed at a portion including at least the through hole hole 11. If the terminal pins are to be brazed to the flat portion of the insulating substrate 10, the flat land-shaped nickel layer 20 may be formed on the portion.

As shown in step (b), after forming a corrosion-resistant alloy layer 30 such as Ni-P covering the entire surface of the nickel layer 20, step (c)
As shown in, a copper layer 40 to be a second conductor metal layer is formed. The copper layer 40 is formed on the surface of the insulating substrate 10 according to a predetermined circuit pattern, and a part of the copper layer 40 is formed so as to be connected to the nickel layer 20 at the brazing point through the corrosion-resistant alloy layer 30. Then, the copper layer 40 and the nickel layer 20 are electrically connected.

In this way, the ceramic wiring circuit board according to the present invention is manufactured. The state in which the terminal pins are brazed and joined to the ceramic wiring circuit board is shown in step (d).

When the terminal pin 50 is arranged on the surface of the nickel layer 20 at the brazing point (in this case, via the corrosion-resistant alloy layer 30 on the surface) through the silver brazing material 60 and heated by a normal heating means, the silver brazing material
The joining action of 60 brazes the terminal pin 50 to the nickel layer 20.

Next, the result of actually manufacturing a ceramic wiring circuit board and verifying its brazing performance will be described.

Example 1 Using a 96% alumina substrate, a nickel layer was metallized to a thickness of about 3 μm on the entire surface of the substrate by sputtering. Then, a predetermined circuit pattern was formed by an ordinary photolithography method. This circuit pattern includes at least a brazing point.
A mixed solution of sulfuric acid and hydrogen peroxide was used as an etching solution in the circuit pattern forming step.

Next, a corrosion resistant alloy layer made of Ni-P (P content of about 13%) was formed on the entire surface of the nickel layer by electroless nickel plating to a thickness of 3 to 5 μm. This corrosion-resistant alloy layer is not attacked by cupric chloride, ferric chloride, etc., which is an etching solution for etching the copper layer in a later step.

A 10 μm copper layer was metallized on the entire surface of the insulating substrate by a sputtering method, and then a predetermined circuit pattern was formed by an ordinary photolithography method. Although cupric chloride was used as an etching solution for the copper layer, no corrosion or dissolution removal was observed in the nickel layer covered with the Ni-P corrosion-resistant alloy layer, and a predetermined circuit composed of the copper layer and the nickel layer was used. A ceramic printed circuit board with a pattern could be manufactured.

For the obtained ceramic printed circuit board, 0.4 mm within the range of 2 mmφ where nickel layer (and corrosion resistant alloy layer) is formed.
20 terminal pins made of 42 alloy of 5 mmφ were brazed and joined by silver brazing. To the sample to which this terminal pin is joined,
When the pin bending test was conducted three times, the results shown in Table 1 below were obtained. In the test, the terminal pin was bent three times and evaluated for peeling at the interface between the ceramic insulating substrate and the conductive metal layer. In Comparative Example 1, an 8 μm copper layer was formed on the same insulating substrate as in Example 1 by sputtering, and then a nickel barrier layer (P content ratio of about 13%) was formed on the surface of the copper layer by 5 to 8 μm. The same test as in Example 1 was conducted by brazing 20 terminal pins in the range of 2 mmφ in the same manner as above.

As a result of the above test, the ceramic wiring circuit board of the present invention,
It was proved that the brazing joint strength to the terminal pin was significantly superior to the conventional one.

Example 2 Using an aluminum nitride substrate, a copper layer of about 10 μm was metallized on the entire surface of the substrate by a sputtering method, and then a predetermined circuit pattern was formed by an ordinary photolithography method. This circuit pattern is formed in the wiring circuit portion excluding the brazing portion described later. A cupric chloride solution was used as an etching solution for forming a circuit.

Next, a Ni—P corrosion-resistant alloy layer (P content ratio of about 13%) was formed in an amount of 3 to 5 μm on the entire surface of the copper layer by electroless plating. This Ni-P corrosion resistant alloy layer is not attacked by a sulfuric acid + hydrogen peroxide mixed solution or an ammonium persulfate solution which is an etching solution for the nickel layer.

Next, after a nickel layer was metallized on the entire surface of the substrate by a sputtering method, a predetermined circuit pattern was formed by an ordinary photolithography method. This circuit pattern is in a state where the nickel layer is directly formed on the surface of the insulating substrate without interposing the copper layer at least at the brazing portion. A mixed solution of sulfuric acid and hydrogen peroxide was used as an etching solution for the nickel layer.
No corrosion or dissolution removal was observed in the copper layer covered with the Ni-P corrosion resistant alloy layer, and a ceramic wiring circuit board having a predetermined circuit pattern composed of the copper layer and the nickel layer could be manufactured.

Table 2 shows the results of three-time pin bending test performed by brazing terminal pins to the obtained ceramic printed circuit board in the same manner as in Example 1. In Comparative Example 2, after forming a copper layer of 8 μm on the same insulating substrate as in Example 2 by sputtering, a nickel barrier layer (P content ratio of about 13%) of 5 to 8 μm was formed on the surface of the copper layer by electroless plating. What was brazed to the formed terminal pins in the same manner as in Example 2 was used.

Comparing the results of the above test and the test results of Example 1 above,
It can be seen that the ceramic printed circuit board according to the present invention can obtain good results regardless of which of the copper layer and the nickel layer is formed first.

-Example 3-Using a 96% alumina substrate whose surface is roughened with an acid or an alkali, the entire surface of the substrate is electroless plated to form Ni of about 1 to 3 μm.
-P (P content approximately 3%) or Ni-B (B content approximately 1)
%) Was metallized, and then a predetermined circuit pattern including a brazed portion was formed by an ordinary photolithography method. A mixed solution of sulfuric acid and hydrogen peroxide was used as an etching solution for forming a circuit.

Next, a Ni-P corrosion-resistant alloy layer (P content of about 13%) is further applied to the entire surface of the nickel layer by electroless plating to a thickness of 3 to 5 μm.
Formed.

Next, a copper layer was metallized to a thickness of 10 μm on the entire surface of the substrate by electroless plating, and then a predetermined circuit pattern was formed by ordinary photolithography. Although cupric chloride was used as an etching solution for the copper layer, no corrosion or dissolution removal was observed in the nickel layer covered with the Ni-P corrosion-resistant alloy layer, and a predetermined circuit composed of the copper layer and the nickel layer was used. A ceramic printed circuit board with a pattern could be manufactured.

Table 3 shows the results of performing a pin bending test three times by brazing terminal pins to the obtained ceramic wiring circuit board in the same manner as in Example 1. In Comparative Example 3, after forming a 10 μm copper layer on the same insulating substrate as in Example 3 by electroless plating, a nickel barrier layer (P content ratio of about 13%) was formed on the surface of the copper layer by electroless plating. A terminal pin was brazed in the same manner as in Example 3 with respect to the one having a thickness of 5 to 8 μm.

-Example 4-A 96% alumina substrate whose surface was roughened with an acid or an alkali was used, and after a copper layer was metallized on the entire surface of the substrate by an electroless plating method, a predetermined circuit pattern was formed by an ordinary photolithography method. This circuit pattern is formed in the wiring circuit portion excluding the brazing portion described later. A cupric chloride solution was used as an etching solution for forming a circuit.

Next, a Ni-P corrosion-resistant alloy layer (P content ratio of about 13%) was formed on the entire surface of the copper layer by electroless plating.

Next, a nickel layer made of Ni-P (P content of about 3%) or Ni-B (B content of about 1%) was metallized to a thickness of 10 μm on the entire surface of the substrate by electroless plating, and then a predetermined photolithography method was used. The circuit pattern was formed. A mixed solution of sulfuric acid and hydrogen peroxide was used as an etching solution for the nickel layer.
No corrosion or dissolution removal was observed in the copper layer covered with the Ni-P corrosion resistant alloy layer, and a ceramic wiring circuit board having a predetermined circuit pattern composed of the copper layer and the nickel layer could be manufactured.

Table 4 shows the results of three-time pin bending test conducted by brazing terminal pins to the obtained ceramic wiring circuit board in the same manner as in Example 1. In Comparative Example 4, after forming a 10 μm copper layer on the same insulating substrate as in Example 4 by electroless plating, a nickel barrier layer (P content rate of about 13%) was formed on the surface of the copper layer by electroless plating. The terminal pins were brazed in the same manner as in Example 4 with respect to those having a thickness of 5 to 8 μm.

From the above test and the test results of Example 3, the ceramic wiring circuit board of the present invention has excellent performance even when not only pure nickel but also a nickel alloy containing a relatively small amount of P or B is used as the nickel layer. It was proved that it can exhibit.

-Example 5-Using an aluminum nitride substrate whose surface is roughened with an alkali, the entire surface of the substrate is subjected to Ni-P (P content of about 3) by electroless plating.
%) Or Ni-B (B content of about 1%) was metallized to a thickness of 1 to 3 μm. A dry film developed in the reverse pattern of the circuit pattern of the nickel layer was formed on the nickel layer as a plating resist, and then a Ni-P corrosion resistant alloy layer (P content ratio of about 13%) was formed by electroless plating. . Next, after removing the resist made of a dry film, a mixed solution of sulfuric acid and hydrogen peroxide is used as an etching solution to selectively etch an unnecessary nickel layer not covered with the Ni-P corrosion-resistant alloy layer. By removing, a nickel layer having a predetermined circuit pattern was formed. The surface of the nickel layer remains covered with the corrosion resistant alloy layer.

Next, a 10 μm copper layer was formed on the entire surface of the substrate by electroless plating, and then a predetermined circuit pattern was formed by ordinary photolithography. Although cupric chloride was used as an etching solution for the copper layer, no corrosion or dissolution removal was observed in the nickel layer covered with the Ni-P corrosion-resistant alloy layer, and a predetermined circuit composed of the copper layer and the nickel layer was used. A ceramic printed circuit board with a pattern could be manufactured.

Table 5 shows the results of three-time pin bending test performed by brazing terminal pins to the obtained ceramic wiring circuit board in the same manner as in Example 1. In Comparative Example 5, after forming a 10 μm copper layer on the same insulating substrate as in Example 5 by electroless plating, a nickel barrier layer (P content ratio of about 13%) was formed on the surface of the copper layer by electroless plating. The terminal pins were brazed in the same manner as in Example 5 with respect to the elements having a thickness of 5 to 8 μm.

[Effects of the Invention] As described above, the ceramic wiring circuit board according to the present invention is such that, in the wiring circuit formed of the conductor metal layer formed on the ceramic insulating substrate, at least at the brazing portion, the nickel layer is directly formed on the substrate surface. Since it is formed, if an external metal member is brazed to this nickel layer portion, problems such as copper erosion phenomenon and reduction of barrier effect due to diffusion of copper and nickel barrier layer do not occur, Adhesion with the wiring circuit at the brazing point can be sufficiently maintained, and the brazing joint strength can be significantly improved as compared with the conventional ceramic wiring circuit board. In addition, since the wiring circuit portion other than the nickel layer is formed of a copper layer having excellent conductivity, the electrical performance is as good as that of the conventional wiring circuit substrate made of only a copper layer. It can also be applied to fine wiring circuits.

Moreover, as in the conventional ceramic wiring circuit board, the method of brazing the copper layer or forming the nickel barrier layer on the copper layer and brazing requires strict control of the brazing process. However, with the ceramic wiring board of the present invention, the adhesion between the nickel layer at the brazing point and the insulating substrate is strong without the need for such strict control, so that the brazing work is easy. And work efficiency can be improved.

According to the method of manufacturing a ceramic wiring board according to claim 2, when the step of forming the wiring circuit portion using the nickel layer and the step of forming the wiring circuit portion using the copper layer are performed in different steps, the wiring circuit previously formed By covering the part with the corrosion-resistant alloy layer, it is possible to reliably prevent the previous wiring circuit part from being corroded or damaged when etching the subsequent wiring circuit part, and the nickel layer and the copper layer are prevented. Efficiently manufacturing a ceramic wiring circuit board having wiring circuits excellent in the function and effect of the invention according to claim 1 which are mixed ceramic wiring circuit boards and excellent in electrical circuit performance and the like. be able to.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing stepwise a manufacturing process and a brazing process of a ceramic wiring circuit board showing an embodiment of the present invention. 10 ... Insulating substrate, 20 ... Nickel layer, 30 ... Corrosion resistant alloy layer, 40 ...
Copper layer, 50 ... Terminal pin, 60 ... Silver brazing material

Claims (2)

[Claims] 1. A ceramic wiring circuit board used by brazing an external metal member to a wiring circuit, wherein at least a conductor metal of a conductor metal layer constituting the wiring circuit constitutes a wiring circuit at a brazing point. A ceramic wiring circuit board, wherein the layer is a nickel layer directly formed on a ceramic insulating substrate, and a conductor metal layer constituting a wiring circuit portion other than the wiring circuit portion made of the nickel layer is a copper layer. 2. A method of manufacturing a ceramic wiring circuit board according to claim 1, wherein a wiring circuit portion made of one of a nickel metal layer and a copper metal layer is first formed, and the metal wiring layer is formed. A method for manufacturing a ceramic wiring circuit board, wherein the entire surface of the substrate is covered with a corrosion-resistant alloy layer, and the wiring circuit portion made of the remaining conductor metal layer is formed by etching.