JPH05275835A - Surface mounting board and its production - Google Patents

Abstract

PURPOSE:To provide a surface mounting board suitable for mounting a finely pitched electronic component and its production. CONSTITUTION:The surface mounting board is constituted of patterned plating resist layer 4 formed on an insulating board 1, a Cu pattern formed on the insulating board 1 at parts other than the plating resist layer 4 and a substituting solder layer 6 generated by nickel/solder replacement based on electroless solder plating process at the part of a nickel layer 5 formed once on the Cu pattern 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mounting substrate and a method for manufacturing the same, and more particularly to a surface-mounting substrate having a structure suitable for mounting fine-pitch electronic components and a method for manufacturing the same. It is about.

[0002]

2. Description of the Related Art With so-called miniaturization of so-called SMT components, surface mounting substrates such as printed wiring boards used for mounting such miniaturized components are also thin, compact and high density. Wiring and surface mounting have been steadily and rapidly spread. For this,
In the hot-dip soldering method which has been conventionally executed in this kind of technical field, there arise problems in controlling the thickness of the generated plating and maintaining its uniformity. Further, when the electrolytic solder plating method is used, it is necessary to provide a plating lead, which reduces the wiring density when forming a required wiring pattern on the substrate. Further, although it may be possible to use the cream solder printing method, there is a limit (for example, a limit of 0.65 mm pitch) accompanying the narrowing of the pitch. That is, the above-mentioned hot-dip solder plating method and cream solder printing method cannot appropriately cope with the recent high density of printed wiring boards and miniaturization of electronic components to be mounted. .. For example, the progress of fineness of the conductor portion of the printed wiring board and the connection pad portion with the lead wire is remarkable, and it is extremely difficult to control the thickness of the plating used, and the thickness of the plating varies. However, the solder may not be sufficiently attached to the fine portion. Also, when the electrolytic solder plating method described above is used, it becomes difficult to energize the independent conductor portions due to the increase in density as described above, and the thickness of the plating layer becomes nonuniform.

Therefore, it is possible to apply an electroless solder plating method in order to break through the bottleneck and promote miniaturization and fineness of the printed wiring board. Since the formation is performed as a substitution reaction with the copper arranged in a thin film on the printed wiring board, a problem such as so-called blistering that affects the adhesion between the copper and the plated solder occurs, When using the printed wiring board, there is a concern about ensuring reliability. In addition, the electroless solder plating method does not show a self-catalytic property with respect to the reducing agent that is usually used, and therefore, the thickness of the solder plating layer required for surface mounting of components is insufficient. (Usually 10 μm or less)
Therefore, it is inevitable to use the cream solder printing method together with the surface mounting method.

[0004]

As described above, in the above-mentioned prior art, in order to cope with the rapid thinning of printed wiring boards, high density wiring, miniaturization of mounted parts, etc., Although some trials and partial implementations of the molten solder plating method, cream solder printing method, electrolytic solder plating method, or electroless solder plating method have been performed, in either case, the thickness of the solder layer is insufficient or necessary. However, there is a problem in that reliable electrical connection cannot be obtained and reliability is poor.

The present invention has been made in order to solve the above-mentioned problems, and has high reliability by utilizing the plating by the substitution reaction of nickel with tin and lead based on the electroless nickel plating method. It is an object of the present invention to provide a surface-mounting substrate and a method for manufacturing the same, which enables to obtain a solder plating layer having a desired thickness.

[0006]

The surface mounting substrate according to the present invention has been made in order to solve the above problems, and is a surface mounting substrate in which a solder layer is formed on a Cu pattern on an insulating substrate. A substrate for use, which has a required pattern of a plating resist layer formed on an insulating substrate, a Cu pattern formed on a portion of the insulating substrate other than the plating resist layer, and nickel once formed on the Cu pattern. In the layer, a replacement solder layer formed by a nickel / solder replacement reaction based on an electroless solder plating treatment is characterized.

The method for manufacturing a surface mounting substrate according to the present invention is also made in order to solve the above-mentioned problems. For surface mounting, a solder layer is formed on a Cu pattern on an insulating substrate. A method of manufacturing a substrate, the method comprising: forming a plating resist layer having a required pattern on an insulating substrate;
a step of generating a u pattern, a step of generating a nickel layer on the Cu pattern, and a step of performing nickel / solder substitution on the nickel layer by applying electroless solder plating. It is a thing.

[0008]

In the surface mounting substrate according to the present invention, the solder layer is formed on the Cu pattern on the insulating substrate, and the plating resist layer having the required pattern formed on the insulating substrate and the insulating substrate are formed. A Cu pattern formed in a portion excluding the plating resist layer above, and a replacement solder layer formed in a nickel layer once formed on the Cu pattern by a nickel / solder replacement reaction based on electroless solder plating treatment; It is composed of And
Due to such a structure, it is particularly suitable for mounting fine pitch electronic components.

Further, in the method of manufacturing a surface mounting substrate according to the present invention, a step of forming a plating resist layer having a required pattern on the insulating substrate and a Cu pattern on a portion of the insulating substrate excluding the plating resist layer. Forming, a step of forming a solder plating resist layer on the plating resist layer of the required pattern, and a step of forming a nickel layer on the Cu pattern,
A step of performing nickel / solder substitution in the nickel layer by applying electroless solder plating. By adopting such a method, it is possible to obtain a surface mounting substrate that is particularly suitable for mounting fine-pitch electronic components.

[0010]

1 is a schematic explanatory view of a surface mounting substrate and a method of manufacturing the same according to an embodiment of the present invention. First, in FIG. 1A, an insulating substrate 1 is made of, for example, glass epoxy resin, and an adhesive layer 2 made of epoxy resin is provided on the insulating substrate 1. Then, the Cu layer 3 having a desired pattern is provided, for example, as a pad portion via the adhesive layer 2, and the plating resist layer 4 is provided so as to fill the void portion, thereby providing a desired surface mounting substrate. Is shown as an additive type substrate for mounting a QFP with a pitch of 0.3 mm, for example. Next, in FIG. 1 (B), electroless nickel plating treatment is performed so that only the upper portion of the Cu layer 3 has a predetermined thickness (for example,
20 μm) of nickel layer 5 is formed. And FIG.
In (C), electroless solder plating is performed, and the following phenomenon occurs. That is, based on the difference in the ionization tendency between nickel and solder, a substitution reaction between nickel and solder in the nickel layer 5 in FIG. 1 (B) occurs, and a predetermined thickness having relatively porosity (for example, 15μ
The replacement solder layer 6 of m) is generated on the Cu layer 3 to form a desired surface mounting substrate. Then, as can be seen in FIG. 1C, the conductor pattern portion on the substrate is the Cu layer 3, the residual nickel layer 8 and the replacement solder layer 7.
Will be obtained as a three-layer structure. Further, it was confirmed that there was no inconvenient blistering between these layers, and that the adhesiveness was extremely good. Furthermore, since the above-mentioned solder plating is provided by applying the electroless method (by replacement with nickel), the plating thickness can be made sufficiently large. Thus, it becomes possible to easily surface-mount electronic components without using the cream solder printing method together. As shown in FIG. 1C, when the residual nickel layer 7 is formed between the Cu layer 3 and the replacement solder layer 6, the residual nickel layer 7 is transferred to the Cu layer 3. It is more preferable because it functions as a so-called barrier layer for preventing solder diffusion.

[0011]

As described above, the surface mounting substrate according to the present invention is a surface mounting substrate in which a solder layer is formed on the Cu pattern on the insulating substrate and is formed on the insulating substrate. The required pattern of the plating resist layer, the Cu pattern formed on the insulating substrate except the plating resist layer, the solder plating resist layer formed on the required pattern of the plating resist layer, and the C
The nickel layer once formed on the u pattern is composed of a replacement solder layer formed by a nickel / solder replacement reaction based on electroless solder plating treatment. Therefore, it is particularly suitable to attach fine-pitch electronic components, and the electroless nickel plating method can be used in the production thereof without the need for combined use with the cream solder printing method. By using the plating based on the substitution reaction of nickel with tin or lead as a base, a solder plating layer having a desired thickness can be obtained with high reliability.

Further, in the method of manufacturing a surface mounting substrate according to the present invention, a step of forming a plating resist layer having a required pattern on the insulating substrate, and a Cu pattern on a portion of the insulating substrate excluding the plating resist layer. Forming, a step of forming a solder plating resist layer on the plating resist layer of the required pattern, and a step of forming a nickel layer on the Cu pattern,
The step of performing nickel / solder substitution in the nickel layer by applying electroless solder plating is characterized in that it includes the step of adopting such a method, as described above, When manufacturing a surface mounting substrate, it is possible to obtain a desired thickness by plating by a substitution reaction of nickel with tin or lead based on an electroless nickel plating method without the need for combined use with a cream solder printing method. The solder plating layer can be obtained with high reliability.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a surface mounting substrate and a method of manufacturing the same according to an embodiment of the present invention.

[Explanation of symbols]

1: Insulating substrate; 2: Adhesive layer; 3: Cu layer; 4: Plating resist layer; 5: Nickel layer; 6: Replacement solder layer; 7: Residual nickel layer;

Claims (2)

[Claims] 1. A surface mounting substrate in which a solder layer is formed on a Cu pattern on an insulating substrate, the plating resist layer having a required pattern formed on the insulating substrate, and a plating resist layer on the insulating substrate. And a replacement solder layer formed by a nickel / solder replacement reaction based on electroless solder plating in the nickel layer once formed on the Cu pattern. Substrate for surface mounting. 2. A method for manufacturing a surface mounting substrate, comprising forming a solder layer on a Cu pattern on an insulating substrate, the method comprising: forming a plating resist layer having a required pattern on the insulating substrate; A step of forming a Cu pattern on a portion excluding the plating resist layer, a step of forming a nickel layer on the Cu pattern, and a step of performing nickel / solder substitution on the nickel layer by applying electroless solder plating. A method for manufacturing a surface mounting substrate, comprising: