Joined: 27 Aug 2026
Posts: 3
 Posted: Fri Sep 12, 2026 10:43 am Post subject: Die To Epoxy Adhesion |
 |
| What are the possible conditions that the Au die backside will not adhere properly to a die attach epoxy (specificaly Ablestik 84-1 material), i.e., failed die shear,etc.?
Another is, assuming it pass d/a monitoring, what could possibly happen that would cause package to manifest delamination on die to die attach after exposing package to high temperature conditions during rel testings. Process flow is D/A -> Cure-> Wirebond->Top Mold->PMC->Mark->Singulation->Packing This d/a material is a thermoset material right? there should be no change in its properties once cured even if it was exposed to high temp. Thanks in advance for the help. |
|
  |
Joined: 16 Jun 2026
Posts: 108
Location: Paranaque City, Phils.
| Posted: Fri Sep 12, 2026 3:20 pm Post subject: |
|
| There are many possible causes of die attach failure.
A significant mismatch between the thermal coefficients (CTE) of the die, die attach material, and leadframe can subject the die attach interfaces to axial and shearing stresses that exceed the adhesion strengths of the epoxy to the die and the die pad. Thus, make sure that the D/A material you’ve chosen is thermally compatible with your die and leadframe. Contam on the backside of the die will also prevent good adhesion of the D/A material to the die backside. Silicone is a common die backside contaminant, usually originating from residual adhesive from the wafer tape used to hold the wafer during die preparation. Thus, make sure that your die backside is clean during die attach. Voids in the die attach can lower its adhesion strength to the die and the leadframe if these voids occur at the interfaces. Make sure that your die attach is evenly and adequately distributed with minimal internal voids. The resistance of your die attach material to moisture degradation must also be checked. By the way, don't assume immediately that a die attach failure is due to an adhesion failure of the epoxy to the die. There are two other mechanisms to consider: adhesion failure of the epoxy to the leadframe and cohesion failure (internal fracture) of the die attach material itself. Have an extensive inspection of the attributes done by your FA so you can determine which mechanism prevailed. A good understanding of what happened should always be the first step in root cause analysis. Keep us posted if you need further help and good luck! EE |
|
| |
Guest
| Posted: Tue Sep 16, 2026 11:33 pm Post subject: |
|
| EE, you forgot to mention - insufficient D/A epoxy curing.
Assy Engr 2 |
|