Laser Diode Submounts (Au/Sn)

Applied Thin-Film Products (ATP) is one of the industry leaders for Laser Diode Submounts with pre-deposited Au/Sn. ATP custom fabricates thin-film submounts with tightly controlled substrate and metal thicknesses for your alignment needs. Hi-thermal conductivity materials include Aluminum Nitride (AlN) and Beryllium Oxide (BeO).

These submounts can have pre-deposited and patterned Gold Tin (Au/Sn) to accommodate lower manufacturing cost, higher volume, and automated assembly of laser diode modules. The use of pre-deposited and patterned Au/Sn replaces the more traditional approach of using thick Au/Sn preforms. ATP’s standard alloy composition is 80% Au and 20% Sn which typically reflows at 278°C under a high purity gas blanket consisting either of forming gas or Nitrogen.

Other Au/Sn custom compositions are available. ATP offers a sputtered and plated Au/Sn eutectic. Samples are available. Please ask for ATP1014S for sputtered, ATP1014P for plated and ATP1014PX for advanced plated AuSn.

In order to strengthen the relationship with our customers, ATP performs Au/Sn reflow tests as a standard practice on each lot to ensure the performance of the Au/Sn meets our customers’ expectation. We offer four standard test profiles for our customers to choose from that would closely resemble their assembly processes:

Laser Diode Submount

Notes: Test Profile 1 is typically recommended for sputtered Au/Sn patterns.
Test Profile 1 is applicable to both plated and sputtered Au/Sn patterns. Test Profiles 2 and 3 are only applicable to plated Au/Sn patterns.
All test were performed at ATP with inert gas.

Custom test profile and the detailed test procedure are available upon request. Die Shear test will be performed on the test die to meet and/or exceed MIL-STD-883.

•Replaces Traditional Au/Sn Preforms

•Accurately Controlled Thickness

•Lot to Lot Consistency

•Reduce Au/Sn Thickness

•Complex Solder Pad Geometries

•Accurate Laser Alignment

Pre-Deposited and Patterned Au/Sn Guidelines

•Smallest Feature Size: 0.0015" x 0.0015" (0.038mm x 0.038 mm)

•Minimum Pitch (minimum space between Au/Sn Pads): 0.003" (0.076mm)

•Typical Au/Sn Thickness: 160–240µ" (4–6 microns) (Thickness outside of the typical range might restrict the process used.)

•AuSn thickness with 3–6µm for sputtered and 4–7µm for plated

•Tolerance on Thickness of Plated Au/Sn: ±80µ" (±2 microns)

•Placement Accuracy of Au/Sn: ±0.0005" (±0.0127mm)

•Dimensional Tolerance on Au/Sn Pad: ±0.0002" (±0.005mm)

•Minimum Pull Back From Laser Cut Edge: 0.0015" (0.0381mm)

•Minimum Pull Back From Conductive Plated Thru Via Holes: 0.0025" (0.0635mm)

ATP circuits with Au/Sn are best assembled when received. Little information is available about long-term storage of thin Au/Sn layers under ambient conditions. Gold Tin intermetallic compounds (IMCs) are known to form at room temperature when excess Au or Sn is present, so compositional changes might occur during long-term storage. To our knowledge, oxidation of Au/Sn IMCs has not been studied but likely is accelerated by high humidity and high storage temperature. Storing the circuits with Au/Sn in a nitrogen purged dessicator may minimize the oxidation effect.