Browse Prior Art Database

a lead frame package with guide ring

IP.com Disclosure Number: IPCOM000202014D
Publication Date: 2010-Dec-01

Publishing Venue

The IP.com Prior Art Database

Abstract

This is an article to introduce an enhanced lead frame. It has 2 or more connecting points with tie bar compared with normal guide ring lead frame, obviously raise the mechanical strength, expand the application areas, and at the same time, no assembly cost added.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 50% of the total text.

Page 01 of 12

a lead frame package with guide ring

Background

   With the intensive requirement of including more and more signals in a single package, It becomes more difficult to have lead frame support complex chip;

   The price competition between chip vendors are tough than before, its need more and more low cost solutions for customer;

Package takes more percentage of total cost than before,

with the higher price of oil and copper.

Problem comes

Lead frame package can't support cross nets between die pad and lead finger;

Traditional lead frame with guide ring is hard to meet the requirement of complex design;

Hard to maintain good signal integrity performance at package level.

1



Page 02 of 12

Prior Arts

United Stated Patent Application Publication No. US1998/5723899

Semiconductor lead frame having connection bar and guide rings

The said method includes:

Some of the inner leads in the four sides are extended and

provided with connection bars on their inside ends;

Diagonally arranged tie bars of the lead frame are extended

and provided with a rectangular guide ring on theirinside ends.

Other patents related to lead frame with bar (Around 5 relative publication searched, no similar

method with our disclosure found)

US 5539251


(This page contains 00 pictures or other non-text object)

2



Page 03 of 12

Proposed Idea -lead frame Design Begin


(This page contains 00 pictures or other non-text object)

In general lead frame package design, we try to maintain same pad sequence on silicon and package. It's hard to make it feasible by normal design methodology when there is big mismatch.

The left figure shows a sketch map of typical lead frame design, package type is SOIC, pad sequence of silicon and lead frame has obviously mismatch due to application reason.

This patent develops a lead frame type to support this kind complex interconnection.

3



Page 04 of 12

Proposed Idea - Primary lead frame design


(This page contains 00 pictures or other non-text object)

Left figure is a general design proposal, similar with prior art.

It's hard to achieve as one connection point between lead finger and long guide ring can not provide enough mechanical stress when wire bonding.

4



Page 05 of 12

Proposed Idea - Lead Frame Design


(This page contains 00 pictures or other non-text object)

The method comprises:

In lead frame design, tie bars are extended and provided with a guide ring on their inside ends. The guide ring has 2 types of pattern, can be extended from bond finger to tie bar (figure A) or tie bar to tie bar (figure B). The guide ring's connecting points with tie bar can be more than 2 (figure C), provide more mechanical intensity for wire bonding, and the points with tie bar will be broken at the "fold" process by punch, which is for electrical separation of the lead fingers. The guide ring functions as a wide mounting place for higher integration, and reduce crossing wire. It also reduce the usage of the adhesive tape in a long finger/guide ring product, simp...