JPS58161760A - Method for plating on aluminum substrate - Google Patents

Abstract

PURPOSE:To form an Ni layer having good adhesion accurately and easily on an Al substrate by coating paste contg. specific ratio of Zn and Ni components on the Al substrate, drying the same and heat-treating the Al substrate at specific temp., then subjecting the substrate to electroless Ni plating. CONSTITUTION:Paste contg. 1-30wt% metallic components contg. 1-100wt% Zn component and 0-99wt% Ni component and contg. 0.1-5wt% Pd component as required is coated on the required parts of an Al substrate and is dried. After the substrate is heat-treated in the atmosphere at 300-600 deg.C, the substrate is heat-treated at 200-410 deg.C in a reducing atmosphere to deposite a fine metallic particle layer and electroless Ni plating is applied thereon to form an Ni film layer. Fine Zn particles of about <=2mu grain size or Zn compds. such as ZnCl2 are used for the Zn component and fine Ni particles of about <=2mu grain size for the Ni component.

Description

DETAILED DESCRIPTION OF THE INVENTION 'Nuclear plating is a method of plating aluminum substrates with good layer density and excellent mass productivity.

Aluminum (Ag) is a metal that is difficult to solder because it has a uniformly thin and strong oxide film layer on its surface.

To this end, various methods have been used to make the AJ surface ready for soldering by subjecting it to various surface treatments.

For example, after pre-treating the Alfe surface by substituting zinc (Zn), nickel (Ni) plating or '@(Cu) plating can be applied, or R4i plating after anodizing treatment.

There is a method of forming a solderable metal layer on the surface of the heel by wet plating, such as a method of applying Cu plating. However, this method has drawbacks such as poor adhesion and difficulty in local plating.

There is also a method of forming a solderable metal on the A1 surface by sputtering or the like, but this method has disadvantages such as rather weak adhesion, poor mass production, and high cost.

A concrete example of conventional circuits requiring soldering on the A4 surface is, for example, an electronic circuit using an Al base. Hybrid integrated circuits used to be made by attaching elements such as resistors, capacitors, and transistors to an insulating substrate such as Ceraminok, but because of their poor heat dissipation, paper transistors that easily generate heat and large When a resistor through which current flows is used, the heat generated causes deterioration of the resistor, transistor, and especially peripheral components. Therefore, a method of improving heat dissipation by using At or the like for the substrate and forming a hybrid integrated circuit thereon with an insulating layer interposed thereon has been adopted. However, when such a configuration is adopted, there is a problem that the insulating layer is pulled out and stray capacitance is generated between the voltage of each transistor or resistor and the substrate, which adversely affects the electric circuit. Occur.

In order to solve this problem, it is necessary to connect the Al substrate to each electrical component, and soldering is preferred as the simplest and most reliable method of connection. Because of this, A
There is a strong need for a method for soldering to g-boards. The present invention has been made in view of the above points, and is made by applying a paste containing a Zn-component to the necessary locations of an Al substrate, drying it, and heat-treating it to precipitate a metal fine particle layer. This invention enables soldering with good adhesion to the substrate. In other words, the present invention is a method for forming plating on an Al substrate.
Instead of the conventional wet Zn replacement method, a paste containing a Zn component is face-dried and then heat treated to precipitate metal particles, but the metal particles deposited on the Al substrate are Ae-Zn on the A1 surface. Since it forms an alloy of , it adheres strongly to the Ag substrate. Since the present invention applies electroless Ni plating on the metal fine particle layer thus formed, a tooth layer with good adhesion can be obtained. Furthermore, the present invention has a starting point that allows the Ni layer to be easily formed only in the necessary pattern portions, since the paste can be easily applied to the required areas using methods such as printing or spraying.

Next, the present invention will be explained in detail according to FIG.

The drawing shows a cross section of an AJ substrate that has been coated with Ni according to the method of the present invention. 1 is an Al substrate, 2 is a metal fine particle layer, and this is made by applying a paste containing a Zn component to the required places. , dried, and heat-treated to precipitate fine metal particles on the surface of the Ae substrate.

The Zn component in this paste is Zn with a particle size of 2μ or less.
Zn fine particles or Zn compounds such as zinc chloride and zinc nitrate can be used. Zn can be easily converted to Ae by heat treatment.
In addition to forming an alloy with Zn powder, sintering of the Zn powders easily occurs, resulting in good adhesion to Al and good adhesive strength of the INi plating film. It is appropriate for the metal component including the Zn component in Beichi Seito to have a power of 1 to 30%; if it is less than 1%, it will be difficult to form a uniform Ni plating film and the adhesion will be poor. If the temperature is exceeded, the adhesive strength with the substrate will weaken and the printing characteristics will become extremely poor.

Furthermore, if a Ni component is included in the metal component, the strength of the Nl plating film will be the same as above, but the composition will be...

If it exceeds 99 degrees, the adhesion will deteriorate. N1by
, fine Ni powder with a particle size of 2 μm or less is good.

Furthermore, if the paste contains a Pd component, the activation for plating will be strengthened, and a uniform plating electrode will be easily formed, and the adhesion 9Mk will also be improved. If the Pd component is less than (J, 1 weight), the effect will not be sufficient, and if it exceeds 6 violets, the adhesive strength will deteriorate, and there will be no cost advantage, which is not preferable. The vehicle used in this paste is ethyl cellulose,
It is made by dissolving resins such as polyvinyl butyral and polyvinylpyrrolidone in solvents such as alcohol, cellosolve, and tabiol.

Apply this paste to the wall cloth, dry it, then heat treat it to create a Z
n'f: Miyamukin pA# particles are precipitated, but this heat treatment is carried out at a temperature of 300 to 600'C in the air to combust the resin content, and then reduced to 200 to 400°C in an atmosphere for 2 meters.
Heat treatment is carried out at a temperature of 10'C.In a single heat treatment at a temperature of less than 300℃ in the atmosphere, the resin content remains as the base without being burned.
Uniform electroless plating is not deposited and strong adhesion occurs. Also, heat treatment at a temperature exceeding 600'C in the atmosphere is undesirable because it causes deformation of the Ag substrate. Regarding heat treatment in a reducing atmosphere, the better the heat treatment temperature, the better the A.
It becomes easier for the metal particles to form an alloy between the e-substrate and the Zn, and the %gg of Zn also becomes easier to occur, resulting in better adhesive strength. 2. However, if the heat treatment temperature exceeds 410° C., Zn will deteriorate, the pattern S degree will deteriorate, and it will be difficult to form a uniform plating film.

If the heat treatment temperature is less than 200'C, adhesion is still insufficient.

3 in the drawing is an electroless Ni plating layer, which is an electroless Ni plating layer on which the above paste has been applied, dried, and heat-treated.
By immersing it in an INi plating solution, an iNi layer is selectively formed only on the paste-applied area.

As mentioned above, in the present invention, it is possible to easily form a Ni layer with good adhesion in the required places on the Al substrate, so it is possible to apply a small amount of soldering butter only to the necessary parts. A4 size boards can be manufactured with good mass productivity.

Examples of the present invention will be described below.

(Execution y1) On the surface of a 0.8B thick Ag substrate, a 6φ pattern of 0 layers and a gold maple component of 0.1 to 5, consisting of a H component of 0 to 10M, was applied.
The amount of 0M is determined, and the resin component is polyvinylpyrrolidone.
An activated paste using a vehicle consisting of terpineol was applied as F8M'l, dried at 120°C for 10 minutes, then heat treated in air at a temperature of 250-650'C for 1 hour, and further heated at 150-450'C in green gas. 2 at temperature
Heat treated for 0 minutes.

Next, this substrate was placed in an uncrowned nickel plating solution consisting of nickel sulfate, citric acid removed, and hyposulfuric acid for 30 minutes.
After dipping for a minute, a Ni plating film of approximately 7μ was deposited on the pattern of the A11' substrate. As the Pd component, fine Pd powder or palladium chloride powder of 2 μm or less was used. The Zn component still contains Zn powder of 2p or less and lnCl.
2 powder wood was used, and a Δi powder of 2μ or less was used for the Ni component.

As a conventional example, cysts are applied to other than the safe parts of the Ag substrate and replaced with hardened i, Zn, and then electroless Ni is applied.
Approximately 7 mel of N1 film was formed by electroplating and Ni electroplating.

For each sample obtained, the plating precipitation state, solderability, and plating adhesive strength were examined, and the results are shown in the table below. In the table, the adhesive strength of the plating was determined by soldering a conducting wire onto the Ni plating layer and measuring the tensile strength.

(Margins below) As is clear from the above explanation and the results in the table, the second substrate on which the Ni plating layer obtained by the present invention is formed has a soldering film with excellent adhesive strength and good solderability. Moreover, since the Ni-plated layer can be formed only in the necessary areas with good movable property, it has great value in industry-F.

[Brief explanation of drawings]

The drawing is a sectional view of an AQ substrate plated with Ni according to the present invention. 1...2 substrate, 2...metal fine particle layer, 3...electroless Ni plating layer. Name of agent: Patent attorney Toshio Nakao and 1 other person2

Claims (2)

[Claims] (1) Zinc content of 1 to 10% in the necessary places on the aluminum substrate
A paste containing 1 to 30% by weight of a metal component of 0 to 99% by weight and a nickel component of 0 to 99% by weight is coated and dried, heat treated in air at mK of 300 to 600°C, and then placed in a reducing atmosphere. A method for plating an aluminum substrate, which comprises precipitating a metal fine particle layer by heat treatment at a temperature of 200 to 410 degrees Celsius, and then forming a nickel film layer thereon by electroless nickel plating. (2) A method for plating an aluminum substrate according to claim (1), characterized in that a palladium component is included in the metal component.