We stock AuSn (gold-tin) solder in the following compositions: - 80/20 (eutectic) - 78/22 - 75/25 - 73/27 AuSn is well suited for integrated circuit chip bonding and die bonding due to its high bond and sheer strength, strong 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 Manufacturable Solution We use the JVD process to deposit eutectic AuSn solder layers with thicknesses typically from 1 to 10 microns, and have deposited over 20 microns. Alloy composition is precisely maintained from source to substrate as we deposit the alloy. Our process does not deposit alternating Au and Sn layers. Metal capture efficiency can exceed 90% with little waste of expensive metal. We do batch or single part processing depending on the substrate, and can handle round wafers, 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 process with the vast majority of jobs not exceeding 110-120° C. We have the ability to deposit up to 4 different source materials in a single run using JVD sources. For example, we can deposit adhesion / diffusion barrier / AuSn / Au layers in a continuous sequence without breaking vacuum. Lead free soldering has become a primary goal in advanced microelectronics, semiconductor packaging and related worldwide markets. We can deposit many of the elements of greatest importance in lead free solder such as Au, Ag, Sn, and Cu, singly or in alloy form, with excellent control over alloy composition. We can deposit solder bumps of extremely small size and high area density by high rate deposition of AuSn through patterned photoresist with feature sizes below 10 microns, e.g.: 3 X 3 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.
JVD’s main innovation is a novel vapor source: a sonic jet of inert gas in “low” vacuum, ~ 1 torr pressure that transports condensable atoms, molecules, or clusters from a nozzle to a substrate. The jet deposits these species efficiently in a small area, less than the size of a dime. Larger areas, an 8″ wafer for example, are coated by imposing a relative 2D motion between substrates and one or more jet sources. This combination of jet sources and relative motion gives JVD great versatility. We have designed a number of jet sources based on different vaporization mechanisms inside the nozzle as illustrated in Figure 1. Ultra high purity Helium or Argon is supplied to the nozzle and exits from it as a jet. Ordinarily, the nozzle pressure is several torr, and the downstream pressure is a torr or less, but the range is wide; in different applications both pressures can be higher or lower. This high purity, high speed gas flow is driven only by mechanical pumps and blowers, a robust technology with fast startup times.
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Other Solders Commonly Used in Microelectronics: SnAg SAC (SnAgCu) 387 and 305 SnInAg 86.9/10/3.1 SnIn 58/42 SnAg 96.5/3.5 and 97.5/2.5 52/48 SnAgSb, SnIn, etc.
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