At Teledyne Advanced Electronic Solutions, we have proven expertise to support both eutectic and epoxy die attach techniques as both methods have benefits and differences.
In epxoy die attach, the conductive epoxy used is a single‑component, silver‑filled paste which has good adhesion and outgassing properties and complies with Method 5011 of MIL‑STD‑883. It is applied to all pertinent areas in one operation by the use of silkscreening techniques. For areas requiring additional non‑conductive epoxy, such as under the body of some sizes of capacitors, manual techniques are used for application. Die attach is then performed using one of several different automatic die attach machines in place at Teledyne. The assembly is then cured at the appropriate time and temperature.
For eutectic die attach, an 80/20 gold/tin eutectic is used. This attach method is used whenever thermal or electrical requirements cannot be successfully met with the use of epoxy. This eutectic requires that the die be metal‑backed either with gold, silver or similar alloys. A preform of the eutectic is placed upon the proper pad and the die is bonded to the substrate on a eutectic die attach machine. Die attach in this fashion can be reworked by remelting the eutectic and removing the die, and replacing it with a new die with added eutectic material.