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US 7,887,928 B2Granted
Coated lead frame
AssigneeFreescale Semiconductor, Inc.
InventorsChao Wang, Qing Chun He, Zhe Li, Zhijie Wang, Dehong Ye
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Abstract
A lead frame having a coating of organic compounds on its lead fingers prevents tin and flux from contaminating the lead fingers after die attach. The coating is removed prior to wire bonding. The coating allows for reliable second bonds (bond between wires and lead fingers) to be formed, decreasing the likelihood of non-stick and improving wire peel strength.
Claims6
A method of preparing a lead frame prior to attaching a semiconductor die to a die flag of the lead frame, the method comprising:
- washing the lead frame in an acid bath;
- performing a first water rinsing operation on the acid washed lead frame;
- neutralizing the acid on the rinsed lead frame;
- performing a second water rinsing operation on the lead frame;
- disposing a coating solution on the lead fingers of the lead frame;
- performing a third rinsing operation on the coated lead frame;
- and
- drying the rinsed, coated lead frame.
5 more elements
Dependencies are inferred from the claim text.