Lead frame and semiconductor device using the same
First Claim
1. A lead frame comprising a plurality of inner leads to be packaged and a plurality of outer leads, each end portion of said outer leads being for connection to a substrate by soldering and having a surface which the relatively good solder wettability from being subjected to surface treatment so as to improve solder wettability at least in the case of solder wettability of said outer leads being insufficient, and each of said outer leads having a portion neighboring to said end portion thereof which has a surface with relatively poor solder wettability from being subjected to surface treatment so as to suppress solder wettability.
1 Assignment
0 Petitions
Accused Products
Abstract
A lead frame having a plurality of inner leads and outer leads, said outer leads being subjected to surface treatment for improving solder wettability at an end portion and to sruface treatment for suppressing solder wettability at least at a portion neighboring to the end portion, or said outer leads being bent 4 times or more, is effective for improving thermal fatigue life and reliability when applied to a semi-conductor device.
-
Citations
20 Claims
- 1. A lead frame comprising a plurality of inner leads to be packaged and a plurality of outer leads, each end portion of said outer leads being for connection to a substrate by soldering and having a surface which the relatively good solder wettability from being subjected to surface treatment so as to improve solder wettability at least in the case of solder wettability of said outer leads being insufficient, and each of said outer leads having a portion neighboring to said end portion thereof which has a surface with relatively poor solder wettability from being subjected to surface treatment so as to suppress solder wettability.
- 5. A semiconductor device comprising at least one semiconductor chip, a lead frame having a plurality of inner leads, wires electrically connecting inner leads of said lead frame to said chip, and an encapsulant encapsulating the chip, the inner leads and wires, said lead frame further comprising a plurality of outer leads, each end portion of said outer leads being for connection to a substrate by soldering and having a surface which has relatively good solder wettability from being subjected to surface treatment so as to improve solder wettability at least in the case of solder wettability being insufficient, and each of said outer leads having a portion neighboring to said end portion thereof which has a surface with relatively poor solder wettability from being subjected to surface treatment so as to suppress solder wettability.
- 10. A semiconductor device comprising at least one semiconductor chip, a lead frame having a plurality of inner leads and a plurality of outer leads, wires electrically connecting inner leads of said lead frame to said chip, and an encapsulant encapsulating the chip, the inner leads and the wire, said outer leads each having a surface on an end portion thereof with relatively good solder wettability from being subjected to surface treatment so that it can be wetted with solder comprising lead and tin, said end portion of the outer lead extending from the end a distance in the range of 25% to 45% of the distance from the end to a point of the outer lead to be bent and at least each portion neighboring to said end portions having a surface with relatively poor solder wettability from being subjected to surface treatment so as to suppress wettability for solder comprising lead and tin.
- 13. A semiconductor device comprising at least one semiconductor chip, a lead frame having a plurality of inner leads and a plurality of outer leads, wires electrically connecting inner leads of said lead frame to said chip, and an encapsulant encapsulating the chip, the inner leads and the wire, each of said outer leads being bent at least 4 times and having an end horizontal portion to be face bonded to a substrate, with the position of a third bending portion from the end being higher than the end horizontal portion.
- 16. A lead frame comprising a plurality of inner leads to be packaged and a plurality of outer leads, each outer lead being bent at least 4 times and having an end horizontal portion to be face bonded to a substrate.
Specification