Microelectronic flip chip packages with solder wetting pads and associated methods of manufacturing

摘要

Processes of assembling microelectronic packages with lead frames and/or other suitable substrates are described herein. In one embodiment, a method for fabricating a semiconductor assembly includes forming an attachment area and a non-attachment area on a lead finger of a lead frame. The attachment area is more wettable to the solder ball than the non-attachment area during reflow. The method also includes contacting a solder ball carried by a semiconductor die with the attachment area of the lead finger, reflowing the solder ball while the solder ball is in contact with the attachment area of the lead finger, and controllably collapsing the solder ball to establish an electrical connection between the semiconductor die and the lead finger of the lead frame.

主权项

1. A method for fabricating a semiconductor assembly, comprising:
forming an attachment area and a non-attachment area on a lead finger of a lead frame, the attachment area being more wettable to an electrical coupler than the non-attachment area during reflow, wherein the electrical coupler includes a solder material; contacting an electrical coupler carried by a semiconductor die with the attachment area of the lead finger; reflowing the electrical coupler while the electrical coupler is in contact with the attachment area of the lead finger; and controllably collapsing the electrical coupler to establish an electrical connection between the semiconductor die and the lead finger of the lead frame; and wherein the method further includes attaching the electrical coupler to a contact pad of the semiconductor die; forming the attachment area and the non-attachment area includes:
depositing a photoresist on a surface of the lead finger containing copper (Cu);patterning the photoresist to form an opening corresponding to the attachment area, the opening exposing a first portion of the surface of the lead finger, a second portion of the surface being covered by the photoresist;depositing silver (Ag) on the first portion of the surface of the lead finger through the opening in the photoresist;removing the photoresist from the second portion of the surface of the lead finger having the deposited silver; andoxidizing the second portion of the surface of the lead finger thereby forming copper oxide (CuxO); controllably collapsing includes:
preventing the electrical coupler from migrating away from the silver in the attachment area with the copper oxide in the non-attachment area; andestablishing an electrical connection between the contact pad of the semiconductor die and the lead finger of the lead frame via the electrical coupler; and the method further includes at least partially encapsulating the semiconductor die, the electrical coupler, and the lead finger with an encapsulant.