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Millivolt resistance on silver plated Aluminum for electrical components.

2000

We are plating silver (15 microns) on Silicon Aluminum alloys (German alloy, LM-25, HE-30 WP) on a fully automatic line having following pre-treatment:

1) Ultrasonic cleaning (Aqueous cleaner)

2) Hot Alkaline cleaning (without NaOH)

3) Acid Dip (75% HNO₃ + 25% HF - 3.5 mints)

4) Double Zincate

5) Silver Plating (40 gms Metal + 100 gms KCN)

The millivolt resistance between two silver plated components is fluctuating from 6 mv to 30 mv. I want to control the mv up to 5 mv. How shall I achieve this?

V.V.Sane
- Mumbai - India

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2000

Apply some silver conductivity paste to the parts before assembly.

  
Tom Pullizzi
Falls Township, Pennsylvania

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2000

Are you referring to CONTACT RESISTANCE? Bright plating systems incorporate carbon and sulphur into the deposits and cause contact resistance to increase. Some plating formulations are specifically made for low contact resistance.

Alternatively use a plain dull bath as per F.A. Lowenheim ["Electroplating" [affil. link to book on Amazon]] or A.K.Graham [Electroplating Engineering Handbook. That should work. Y.V.Deval

Yashawant V. Deval
electroplating shop - Pune, Maharashtra, India