MIL-PRF-38535K
APPENDIX F
F.4.4.2 Visual inspection of bond. Visual inspection of bond is required prior to encapsulation. Sample size and
accept/reject limits shall be documented and determined by the manufacturer, and, at a minimum, shall include the
following criteria:
a. ILB lead to bump alignment.
b. Lead contact length; bond lead contact length (L) shall be greater than the lead width (W). (See figure F-1.)
c. Lead side edge overhang shall be evaluated.
d. No open/lifted, peeling, or missing leads.
e. No visual shorts.
f. Cracks in bumps, thin film gold bump pad, glassivation, metal, or active area adjacent to the inner lead bond
bumps shall not exceed the characterization requirements in F.4.4.1.
g. For single point bonds, the tool impression shall cover 100 percent of the lead to bump contact
width.
h. For alloy bonds, fillet shall be visible on at least one side of the lead continuously across the bump.
F.4.5 Encapsulant. The following items a - h, as a minimum, shall be baselined by the manufacturer, and items
g - h shall be sampled on a frequency basis necessary to demonstrate process control.
a. Coefficient of thermal expansion and relationship to underlying layers.
b. Presence of volatile components.
c. Gel time and temperature.
d. Cure profile (initial, ramp, and final): Time and temperature.
e. Final properties of cured polymer.
f.
Storage of encapsulant.
g. Thickness.
h. Viscosity.
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ACTEL [ Actel Corporation ]
