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 and ATP1014P for plated.

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 three standard test profiles for our customers to choose from that would closely resemble their assembly processes:

Test Profile Profile Detail Placement of test die on Au/Sn Pattern Scrub On/Off

Circuit with Au/Sn pattern is
placed on work holder which is
at 290–305°C for 5 seconds

After the circuit with Au/Sn pattern is placed on work holder On

260°C ± 5°C soak for 1 min

Ramp to 290–305°C and stay
for 5 seconds

As the beginning of the soak and the test die is held down until completion of the profile Off

200°C ± 5°C soak for 2 seconds

Ramp to 290–305°C and stay
for 5 seconds

After ramp temparature is reached On

Note: 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.

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

Homogeneous 80% Au/20% Sn

Complex Solder Pad Geometries

Accurate Laser Alignment

Pre-Deposited and Patterned Au/Sn Guidelines

Smallest Feature Size: 0.003" x 0.003" (0.076mm x 0.076 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.)

Minimum Sputtered Au/Sn Thickness: 80µ" (2 microns)

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.

  Laser Diode Submount

Laser Diode Submount

ATP1014P: Plated before reflow

ATP1014P: Plated before reflow

ATP1014P: Plated after reflow

ATP1014P: Plated after reflow

ATP1014S: Sputtered before reflow

ATP1014S: Sputtered before reflow

ATP1014S: Sputtered after reflow

ATP1014S: Sputtered after reflow

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