QFN Device Having A Mechanism That Enables An Inspectable Solder Joint When Attached To A PWB And Method Of Making Same
AssigneeTexas Instruments Incorporated
InventorsAbram Castro, Usman Chaudhry, Joe Adam Garcia, Mahmud Halim Chowdhury
Life of this patent
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Abstract
An apparatus and method for providing an artificial standoff to the bottom of leads on a QFN device sufficient to provide a gap that changes the fluid dynamics of solder flow and create a unique capillary effect that drives solder up the of leads of a UN device when it is attached to a printed wiring board (PWB).
Claims22
An integrated circuit package, comprising:
- a plurality of leads embedded in an encapsulant, said leads having a bottom surface and at least a portion of a side surface exposed from said encapsulant;
- and
- a standoff on said bottom surface of each of said leads.
An apparatus, comprising:
- a printed wiring board including metal traces on a top surface thereof;
- an integrated circuit package mounted on said printed wiring board, said integrated circuit package including a plurality of leads having a bottom surface and at least a portion of a side surface exposed from said encapsulant, said integrated circuit package further including a standoff on said bottom surface of each of said leads;
- and
- solder joining said metal traces of said wiring board to said standoff, said bottom surface, and said at least a portion of said side surface of said leads, said solder including a fillet that covers at least a portion of said portion of said side surface of said leads.
A method of mounting an integrated circuit package to traces on a printed wiring board, said integrated circuit package comprising leads embedded in an encapsulant, wherein a bottom surface and at least a portion of a side surface of said leads are exposed from said encapsulant, said method comprising the steps of:
- forming a stud bump on said bottom surface of at least one of said leads;
- joining said stud bump, said bottom surface of said lead, and said traces on said printed wiring board with solder;
- and
- reflowing said solder such that said solder extends from said bottom surface of said lead to cover at least a portion of said portion of said side surface of said leads.
A method of making an integrated circuit package, comprising:
- providing a plurality of leads embedded in an encapsulant, said leads having a bottom surface and at least a portion of a side surface exposed from said encapsulant;
- and
- providing a standoff on said bottom surface of each of said leads.
Dependencies are inferred from the claim text.