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 ENEPIG
ENEPIG is suitable for soldering, gold wire bonding, aluminum wire bonding and contact resistance. It is formed by the sequential deposition of electroless Ni (120 to 240 micro inches) followed by 2 to 8 micro inches of electroless Pd with an immersion gold flash of 1 to 2 micro inches on the top.
What is ENEPIG?
ENEPIG or Electroless Nickel - Electroless Palladium - Immersion Gold is a surface finish for Printed Circuit Boards that has been around for a decade but is only recently coming back into vogue. The high price of palladium had kept it out of reach out of most businesses. With the price of palladium less than the price of gold, this surface finish becomes the best choice for wire bonding, ROHS assembly and just all boards overall. ENEPIG works by creating a high strength solder connection with the LF alloy. When compared to the solder joint formed with eutectic solder it does not perform as well. (Eutectic means its 63% tin and 37% lead.) ENEPIG is called the "Universal" surface finish as it can be applied to anything.

So why is ENEPIG the "universal" finish?
Excellent ROHS and leaded solderability
  • Because the gold and nickel don't mix, it is easier to solder to it.
High wire bond pull strengths (aluminum wire: 10g; gold wire: (8 -10g).
  • After numerous tests, it withholds high weights.
  • Good for aluminum wedge and gold ball bonding
Low contact resistance
  • Since there is less gold, there is more uniform resistance so it's easier to predict amperage.
Suitable for conductive adhesives
  • You can connect components without the use of solder.
Finish is corrosion resistant and pore-free
  • Because there is less mix and nickel is more insulated, it does not corrode.
Unlimited shelf life.
  • Doesn't tarnish
Palladium acts as an additional barrier layer to further reduce copper dissolution during wave solder, thus ensuring good solderability.
  • Pd prevents the mixing of nickel and gold.
Immersion deposits tend to exhibit poor adhesion. ENEPIG delivers great solder joint strength with various alloys during multiple reflow soldering, especially SAC305. The middle palladium layer helps drastically to stabilize and control the gold and nickel on the two sides around it. Because of the mixture, ENEPIG after testing showed amazing wire bonding both with aluminum and gold. Click here for more on this topic.

Sierra Circuits offers the option for ENEPIG finish on all its products. Please contact your sales person for details.
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