Gold-tin solder alloys, with compositions ranging from the eutectic 80/20 Au/Sn to 70/30, are used for integrated circuit chip or die bonding, because of their high bond strength, adhesion, resistance to creep, low stress, corrosion resistance, good thermal conductivity and absence of whisker formation. Solder preforms are costly, and become difficult to use as required sizes shrink. Solder pastes can have both process capability issues and shortcomings in high performance device reliability and durability.
JVD™ thin film AuSn solder layers offer a fast, low cost solution.
We use the JVD process to deposit eutectic AuSn solder layers with thicknesses typically from 1 to 10 microns, and sometimes over 20 microns. Alloy composition is precisely maintained from source to substrate, and we deposit the alloy, not alternating Au and Sn layers. Metal capture efficiency can exceed 90% with little waste of expensive metal. We do batch or single part processing, coating ceramic squares and rectangles, Si and III-V wafers in sizes ranging from 2" to 8", down to the smallest submounts and heatsinks in custom holders. Patterned photoresists remain cool during our deposition process. The deposition rates are high: coating of a 4" Si wafer with 5 microns of AuSn takes about 10 minutes.
We can also couple AuSn deposition with our Ti-Pt-Au deposition process. We thus offer deposition of the entire structure of adhesion layer plus diffusion barrier layer plus gold-tin solder layers using JVD jet sources, in a continuous sequence, without any vacuum break.
Lead free soldering has become a number one goal in advanced microelectronics, semiconductor packaging and related worldwide markets. Some of the elements of greatest importance for lead free solders are Ag, Au, Bi, Ga, Ge, Mg, Sn, and Zn. We can deposit all of these at very high rate in JVD, singly or in alloy form, with near perfect control over alloy composition.
We can deposit solder bumps of extremely small size and high area density; we use high rate JVD deposition of AuSn through patterned photoresist with feature sizes well below 10 microns, e.g.: 4 X 4 microns with 8 micron pitch.
Related information on JVD advantages and capabilities for lead free solder deposition can be found in the Technology - JVD™ Processes section.
For additional information click here for the February 2003 article on JVD gold-tin solder in Advanced Packaging magazine.
For information on availabilities and pricing, please contact us.