July: Surface finishes

What surface finishes are being offered by SCHWEIZER?

SCHWEIZER is offering the following surface finishes:

  • chemical tin,
  • ENEPAG (Electroless Nickel Electroless Palladium Autocatalytic Gold),
  • HAL (Hot Air Levelling),
  • OSP (Organic Surface Protection),
  • chemical nickel-gold (ENIG, or Electroless Nickel Immersion Gold ),
  • chemical and galvanic silver (provided by subcontractor),
  • galvanic hard gold or fine gold.

 

For what purposes are the surface finishes being used?

  • ENIG: for aluminium wire bonding and/or as high-quality surface finish for soldering via paste printing,
  • ENEPAG: for gold wire bonding,
  • chemical tin: as standard surface finish for soldering via paste printing,
  • HAL: soldering surface which carries the solder as a depot,
  • OSP: most favourable surface finish for soldering via paste printing,
  • galvanic hard gold: for mechanical sliding areas or plug-in contacts.

 

Which layer thicknesses can be produced?

Table surface finishes

 

What storage time can we guarantee for what surface finish?

SCHWEIZER always guarantees a solderability of 6 months for all surface finishes. With proper alignment of the storage conditions and for certain surface finishes, we can guarantee up to 12 months.

 

What is the difference between ENEPAG and ENEPIG?

ENEPAG: Electroless Nickel - Electroless Palladium - Autocatalytic Gold
ENEPIG: Electroless Nickel - Electroless Palladium - Immersion Gold
In the ENEPIG process, gold is deposited on the surface in an exchange reaction. This exchange reaction produces different layer thicknesses on the different pad sizes. This makes it difficult to perform gold wire bonding. ENEPAG is a reductive gold deposition process that produces a homogeneous layer distribution of the gold layer. Therefore, this surface is ideally suitable for gold wire bonding.

 

Why is Schweizer using ENEPAG for gold wire bondable surfaces instead of ENEPIG?

The surface in the ENEPAG process has a purer gold surface, which is required for bonding. Over the course of the process, the layer thicknesses can be achieved more quickly and more homogeneously. The comparable gold process would be galvanic fine gold, which is more complex and more expensive to produce, hence applying the ENEPAG process results in a cost reduction for our customers.

 

What is the difference between galvanic fine gold and hard gold?

Fine gold is 99.99% pure gold, while hard gold is an alloy containing cobalt and making the gold harder and more abrasion-resistant. Fine gold is used as an alternative for gold wire bonding surfaces, while hard gold is used for mechanical requirements.