JPS6196098A - Gold plated electronic parts - Google Patents

Abstract

PURPOSE:To manufacture Au plated electronic parts preventing the stripping of the plating and having high reliability by successively plating electronic parts with Ni and Co before plating with Au. CONSTITUTION:A dibonding pad 2a, a wire bonding pad 2b and pads 2c each provided with a lead are formed on a multilayer wiring ceramic board 1 for mounting a semiconductor. Ni films 3 are formed on the pads 2a, 2b, 2c by electroless plating or electroplating, and leads 5 are connected to the pads 2c with eutectic Ag brazing filler metal 4. Ni films 6 of 2-5mum thickness are further formed by electroplating. The Ni films 6 are plated with Co 7 to 0.5mum thickness, and Au films 8 of 2mum thickness are formed on the Co films 7 by plating. A semiconductor pellet 9 is then dibonded with wires 10, a sealing cap 11 is airtightly put on the board 1 and the leads 5 are dipped in molten solder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electronic component having gold plating on a metal surface.

[Background of the invention]

In electronic parts, gold has die bonding properties.

Due to its excellent wire bondability, solderability, heat resistance, color corrosion resistance, etc., it is widely used for gold plating on various electronic components.

The manufacturing method for electronic components using metallized ceramic is to form electroless nickel plating or electrolytic nickel plating film on the metallized layer, then attach leads with eutectic Ag row, and then electrolytic nickel or electrolytic gold plating. However, the heating conditions (for example, 450° C. for about 110 minutes) during semiconductor packaging are harsh. In particular, by heating the glass seal after die bonding and wire bonding, the silicon in the die bonded pellets diffuses into the nickel applied as the base plating for gold plating, forming a nickel-silicon alloy layer, and forming a nickel-silicon alloy layer. A defect occurs in which plating peels off from the interface between the silicon alloy layer and the nickel layer where silicon has not diffused, which poses a major problem in terms of reliability. To counter this, there is a method of applying heat treatment (at a temperature slightly lower than the melting point of Ag solder for attaching leads) after electrolytic nickel plating, which is applied as a base plating for gold plating, but the heating conditions must be strictly controlled. At the same time, since heat treatment is performed after electrolytic nickel plating, gold plating cannot be performed continuously, the number of steps increases, and productivity decreases.

In addition, for the purpose of thinning the gold plating layer, N1-Co alloy plating (Japanese Patent Laid-Open No. 55-5469
2) or Rh plating (% 1986-4955)
) are being considered.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable electronic component without peeling of plating.

[Summary of the invention]

By electrolytically plating nickel as a base for gold plating and then plating cobalt on top of it, we have found that cobalt acts effectively as a barrier to prevent the silicon in the pellet from diffusing into nickel during the severe heating during semiconductor packaging. This is what I discovered. Because cobalt prevents the diffusion of silicon, there is no plating failure phenomenon without heat treatment after electrolytic nickel, and it is highly reliable and can be performed continuously with electrolytic nickel, cobalt, and gold plating. .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

A multilayer wiring ceramic substrate 1 on which a semiconductor is mounted has a die bonding pad 2ae and a wire bonding pad 2.
b. It has pads 2C with leads, and these pads are W
Or use a high melting point metal paste such as pigeon. This is formed by a screen printing method or the like before sintering the ceramic, and when the ceramic substrate 1 is sintered, the ceramic and these metals are mutually sintered, and the metallized pads 2a to 2C integrated with the ceramic are formed. It is formed. Thereafter, a nickel plating film 3 is formed electrolessly or electrically on this pad. Pad 2C which then requires a lead connection
For example, the leads 5 are connected by a brazing method using a eutectic silver brazing material 4. Subsequently, a nickel plating film 6 with a thickness of 2 to 5 μm is formed by electroplating (eg, Watt bath, sulfamic acid bath). Then, on this nickel plating film 6, α5 μm cobalt plating 7 (cobal sulfate) 4sog
/j, [Chemical: l Hull] 45g/l, boric acid 40g/l), and then gold plating film 8 (for example, Temperex 401 using pure gold plating liquid made by EEJA) was applied on top of it. Two capes are formed. After gold plating, the semiconductor pellet 9 is die-bonded, and after bonding with a wire 10, it is hermetically sealed with a sealing cap 11 (for example, made of ceramic and printed with glass), and then the lead 5Vc solder dip is performed.

After gold plating, various evaluation tests were conducted. Bonding was carried out at 430°C in a nitrogen atmosphere while scrubbing the pellets, and the gold/silicon eutectic was 90% fluoroscopically determined.
Items that were wetter than above were considered good. After that, the die-bonded sample was heated in air at 460°C for 0.15 minutes, and then subjected to a temperature cycle test (e.g. +1509C, -55°C).
C,500-.

1,000 cycles), and those with no peeling of the plating under the pellets were considered good. In all cases, sufficiently good results were obtained with no abnormalities observed. Also, good results were obtained in terms of wire podding and lead soldering.

Na% j-L :! n! m ml (+
t+II-L'E-1, #+LetoM'-i: #Although an example of a cage is shown, it can be similarly applied to a leadless package.

〔Effect of the invention〕

According to the present invention, a highly reliable gold-plated electronic component without peeling of the plating can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention. 1... Multilayer ceramic substrate, 2a... Die bonding pad, 2b... Wire bonding pad,
2C... Hat with lead, 3... Nickel plating film, 4... Eutectic Ag brazing material, 5... Lead, 6...
- Electrolytic nickel plating film, 7... Electrolytic cobalt plating film, 8... Electrolytic gold plating film, 9... Semiconductor pellet, 10... Wire, 11... Sealing cap.

Claims (1)

[Claims] A gold-plated electronic component in which gold plating is applied to a metal surface, and the electronic component is characterized in that cobalt plating is applied on the nickel plating, and gold plating is applied on the cobalt plating.