Electronics Plating Services in Texas

The underplate and the porosity of the deposit, more than its thickness. A nickel barrier stops base metal diffusing into the contact zone, and gold thickness is set by wear cycles and porosity rather than by conductivity, since even a thin continuous film conducts. On an aluminum grounding surface the equivalent question is which conversion coating class the drawing calls — the classes and their contact-resistance limits are on the MIL-DTL-5541 chem film specification page.

Three things dominate: intermetallic growth at the tin-to-copper interface as parts age or see heat, organic co-deposits carried in from a brightener system, and a nickel underplate that passivated before the tin went over it. Matte tin avoids the brightener problem and ages more predictably, which is why it is the usual specification where parts sit in stores before assembly. Matte tin runs at our Rowlett plant.

Silver migrates. Under bias, humidity and surface contamination it grows dendrites across an insulating gap, so closely spaced conductors on an exposed connector or board are the wrong application for it. Silver is the right answer where spacing is generous and current is high — the thickness classes and callouts are covered on silver and gold plating specifications.

Tarnish is a sulphide film, and it comes from packaging and storage at least as often as from the plating line. Parts receive an antitarnish post-treatment where the drawing permits one, and are packed away from sulfur-bearing materials such as ordinary kraft paper and rubber bands. Bright and semi-bright silver run at our McAllen plant.

No. We offer copper only as an undercoat, never as a finished surface, because bare copper grows a resistive oxide and a semi-conductive sulphide in service. For a conductive final surface the stack is normally nickel then silver or tin, which gives the conductivity without the oxide problem. Types of metal plating and finishing compares those options side by side.

Selective plating is done by masking or by racking that isolates the area electrically, and how cleanly the boundary holds depends on the tolerance the drawing allows there. Give a dimensioned plate-to line and a permissible overrun instead of “contact area only”, and say whether the underplate is allowed to extend past the gold. The design guide covers masking, rack-contact marks and where to place them.