The Temperature Cycle was harsh,very harsh from 20°C all the way up to 250°C!! We wanted to see what would happen on a larger piece of Finar Buffer (25 x 6 x 2 mm) placed between a rectangle of solid copper (35 x 6 x 0.4 mm) and a rectangle of AlN (25 x 6 x 0.35 mm) substrate using an epoxy resin attach at both interfaces. The Temperature C was cycle was 3 min ramp up / 1 min plateau / 8 min ramp down.
To attach structures composed of copper (CTE 17) and AlN (CTE 5), with a high CTE mis-match is very challenging. Typically, for dimensions larger than 10mm, a very thick soft solder layer and mold compression is required.
As a benchmark we first tested the copper attached directly to the AlN substrate using epoxy resin. This composition failed during the first cycle at < 200C!
We then tested the composition using Finar Buffer and successfully completed 60 cycles over a 12 hour period, there was no failure, no peeling no curvature.
In addition to this significant result we have prepared an analytical model. This shows that the Shear Stress using FB is 2 ORDERS OF MAGNITUDE LOWER than standard solutions and Peeling Stress using FB is 5 ORDERS OF MAGNITUDE LOWER than standard solutions. Deformation is virtually BENDING FREE, this has a MASSIVE IMPACT ON RELIABILITY!
Send us an email and we will happily send you the Full Report.