Leadframe Leadfinger Support for IC Package Bump Control
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Solution Overview
Problem
Integrated circuit packaging faces challenges such as bump collapse, manufacturing yield, and device reliability due to issues like bump spread distance and paddle damage, which are exacerbated by the need for smaller features in increasingly compact electronic devices.
Innovation Solution
The introduction of a leadframe with a leadfinger support of predetermined height and a wetting surface, which controls the collapse height and spread distance of electrical interconnects, allowing for precise positioning and reduced stress on the integrated circuit die, thereby simplifying encapsulation and cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the integrated circuit package size is reduced to meet demand for smaller electronic devices, then the area and volume of the package are reduced, but manufacturing yield and reliability deteriorate due to bump collapse, bump spread distance issues, and paddle damage
Solution Approach 1:
The leadframe is segmented into multiple functional regions: a support portion extending beneath the die attach paddle, and a die attach paddle portion. This segmentation provides structural reinforcement in critical areas while maintaining overall package miniaturization, thereby improving manufacturing yield without increasing overall package size.
Solution Approach 2:
The support portion of the leadframe is pre-formed to extend beneath the die attach paddle before die mounting. This preliminary structural preparation prevents paddle damage and controls bump collapse during subsequent manufacturing processes, improving reliability in smaller packages without requiring larger dimensions.
2Volume of moving object
If the integrated circuit package size is reduced to meet demand for smaller electronic devices, then the area and volume of the package are reduced, but device reliability deteriorates due to paddle damage and bump collapse
Solution Approach 1:
The leadframe is divided into a support portion and a die attach paddle portion, concentrating structural reinforcement where needed. This segmentation allows the package to maintain strength and resist paddle damage while keeping the overall volume reduced for smaller electronic devices.
Solution Approach 2:
The support portion of the leadframe provides localized structural reinforcement beneath the die attach paddle. This local quality enhancement strengthens critical areas against damage while maintaining overall package miniaturization, resolving the contradiction between reduced size and improved strength.
3Reliability
If the bump collapse is allowed to occur during reflow, then the electrical interconnect bonds are formed, but the spacing is reduced which restricts access for encapsulation, cleaning or other post-connection operations
Solution Approach 1:
The support portion of the leadframe acts as an intermediary structure that manages bump collapse. It provides a controlled surface for bump formation while maintaining adequate spacing, thereby ensuring both reliable bonding and sufficient access for subsequent encapsulation and cleaning operations.
4Device complexity
If the leadframe structure is simplified to reduce manufacturing complexity, then the device complexity is reduced, but manufacturing precision deteriorates due to uncontrolled bump collapse and spread distance
Solution Approach 1:
The leadframe is segmented into a support portion and a die attach paddle portion, providing built-in control for bump collapse and spread distance. This segmentation maintains manufacturing precision without requiring complex external fixtures or additional process steps, thus not increasing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides controlled bump collapse and spread, reduces stress on the die, and eliminates the need for a die attach paddle, enhancing manufacturing yield and reliability while enabling efficient and cost-effective manufacturing of smaller integrated circuit packages.
Implementation Method 1
A bump is placed onto the integrated circuit die contact, heated, and cooled to reflow the alloy to form a bump and to bond the bump to the integrated circuit die
Data Source
AI summary
An integrated circuit package system including forming a leadframe having a lead with a leadfinger support of a predetermined height, and attaching an integrated circuit die with an electrical interconnect at a predetermined collapse height determined by the predetermined height of the leadfinger support.