Lead Frame Etching for Isolated IC Contacts
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Solution Overview
Problem
Current integrated circuit packaging systems face challenges in reducing package size, increasing lead density, and improving reliability due to lead bending and spacing limitations, which affect performance and manufacturing efficiency.
Innovation Solution
The method involves using a pre-plated leadframe with isolated contacts and die paddle pads, encapsulating an integrated circuit die, and exposing only the contact and die paddle pads on the bottom surface of the encapsulation to reduce solder shorts and allow closer spacing of leads, enabling smaller or denser packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lead spacing is reduced to increase lead density, then the number of connections increases, but leads bend easily causing open or short circuits
Solution Approach 1:
The lead frame is segmented into isolated contacts that are electrically separated from each other through etching away the connecting material. This segmentation allows each contact to be independently supported, preventing bending and maintaining reliability while enabling closer spacing and higher connection density.
Solution Approach 2:
The connecting material between leads is extracted through etching, removing the structural support that causes leads to bend. This extraction of material creates isolated contacts that are more stable and reliable, while still allowing high-density interconnections through the substrate.
2Volume of moving object
If package size is reduced to meet portability requirements, then device dimensions decrease, but lead spacing must be reduced which increases bending risk
Solution Approach 1:
By segmenting the lead frame into isolated contacts, the invention enables closer spacing without compromising lead stability. Each isolated contact is independently supported, allowing the package to be smaller while maintaining reliable electrical connections.
Solution Approach 2:
The invention transitions from planar lead spacing to three-dimensional isolation, where contacts are separated vertically and electrically through etched cavities. This dimensional change allows closer horizontal spacing while maintaining structural integrity through vertical support.
3Length of moving object
If lead thickness is reduced to minimize package dimensions, then space is saved, but leads become more flexible and prone to bending
Solution Approach 1:
Segmenting leads into isolated contacts provides individual support structures for each contact, allowing thinner leads to maintain their position and electrical connection without relying on thickness for rigidity. The isolation prevents bending by eliminating the flexible connecting material between leads.
4Ease of manufacture
If traditional lead frame packaging is used, then manufacturing is simple, but solder shorts occur due to exposed lead surfaces
Solution Approach 1:
The etching process extracts and removes excess lead material and connecting structures, leaving only the necessary contact pads exposed. This selective removal prevents solder shorts by ensuring only designated areas are exposed for soldering, while maintaining manufacturing simplicity through a single etching step.
Data Source
AI summary
A method of manufacture of an integrated circuit packaging system includes: providing a pre-plated leadframe having a contact pad and a die paddle pad; forming an isolated contact from the pre-plated leadframe and the contact pad; mounting an integrated circuit die over the die paddle pad; and encapsulating with an encapsulation the integrated circuit die and the isolated contact, the encapsulation having a bottom surface which is planar and exposing in the bottom surface only the contact pad and the die paddle pad.