Abstract A flexible substrate based BGA package mainly comprises a semiconductor chip securely attached onto a flexible film substrate through a nonconductive adhesive. The flexible film substrate is formed from a flexible film having a chip attaching area for carrying the semiconductor chip. The upper surface of the flexible film is provided with a plurality of chip connection pads, a plurality of solder pads, and at least a dummy pad which is disposed centrally on the chip attaching area. The purpose of the dummy pad is to increase the rigidity and strength of the central part of the chip attaching area. The chip connection pads are arranged about the periphery of the chip attaching area for electrically connected to the semiconductor chip. The solder pads are disposed about the dummy pad(s) and electrically connected to the corresponding chip connection pads. The flexible film has a plurality of through-holes formed corresponding to the solder pads such that each solder pad has a portion exposed within the corresponding through-hole for mounting a solder ball. A package body is formed over the semiconductor chip and the upper surface of the flexible film substrate.
A method for manufacturing a flexible film substrate comprising the steps of: providing a flexible film having opposing upper and lower surfaces, the upper surface of the flexible film has a chip attaching area adapted for supporting a semiconductor chip; forming a plurality of through-holes in the flexible film; laminating a metal layer on the upper surface of the flexible film; and etching the metal layer to form a plurality of solder pads, chip connection pads, conductive traces, and at least a dummy pad, wherein the solder pads are disposed corresponding to the through-holes and electrically connected to the chip connection pads through the conductive traces, and the dummy pad is disposed centrally on the chip attaching area.
Claim 2
Independent Claim
118 words
A method for manufacturing a flexible film substrate comprising the steps of: providing a flexible film having opposing upper and lower surfaces, the upper surface of the flexible film has a chip attaching area adapted for supporting a semiconductor chip; forming a plurality of through-holes in the flexible film; laminating a metal layer on the upper surface of the flexible film; and etching the metal layer to form a plurality of solder pads, chip connection pads, conductive traces, and at least a dummy pad, wherein the solder pads are disposed corresponding to the through-holes and electrically connected to the chip connection pads through the conductive traces, and the dummy pad is disposed centrally on the chip attaching area.
Claim 3
Dependent Claim
16 words
The method as claimed in claim 1 , wherein the flexible film is made of polyimide.
Claim 4
Dependent Claim
16 words
The method as claimed in claim 1 , wherein the metal layer is a copper foil.
Claim 5
Dependent Claim
25 words
The method as claimed in claim 3 , further comprising a step of forming a cupric oxide coating on the surface of the dummy pad.
Claim 6
Dependent Claim
20 words
The method as claimed in claim 4 , wherein the cupric oxide coating is formed by means of anodic oxidation.
Claim 7
Dependent Claim
20 words
The method as claimed in claim 4 , wherein the cupric oxide coating is formed by means of chemical oxidation.