Laser-Cut Lead Frame Step Features for Tighter IC Package Tolerances
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Solution Overview
Problem
Traditional lead frame fabrication for integrated circuit (IC) packages through chemical etching is inefficient, costly, and limits miniaturization due to imprecise shaping and high costs, especially for smaller chip designs with tight tolerances.
Innovation Solution
A method involving a two-step process where an incomplete lead frame portion is first formed with through-holes using a punch press or chemical etching, followed by laser-cutting to create three-dimensional step features and through-holes, forming a completed lead frame sheet that can include additional features like grooves and stress-release features, which is then coupled with IC dies and packaging material to form IC packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical etching is used to fabricate lead frames, then the lead frames can be formed with divisions and separations, but the manufacturing precision and cost-effectiveness deteriorate due to imprecise shaping and high costs
Solution Approach 1:
The patent replaces the chemical etching process with a laser-based cutting system. The laser cutting apparatus uses a focused laser beam to precisely cut through the lead frame material, eliminating the need for chemical etchants and providing superior shaping precision while reducing manufacturing costs and environmental concerns.
Solution Approach 2:
The patent changes the fundamental processing parameter from chemical concentration and exposure time to laser power, speed, and focal position. This parameter transformation enables precise control over the cutting process, achieving high manufacturing precision while simplifying the fabrication process and reducing costs.
2Manufacturing precision
If traditional etching processes are used, then lead frames can be formed, but miniaturization is limited due to imprecise shaping and inability to meet tight tolerances
Solution Approach 1:
The laser cutting system provides non-contact, highly precise cutting capability that can achieve tight tolerances required for miniaturized chip designs. The focused laser beam can create extremely precise divisions and separations in the lead frame, enabling support for smaller chip sizes that would be impossible with traditional chemical etching.
3Productivity
If chemical etching is used to form lead frames, then the process can create divisions and separations, but the productivity deteriorates due to inefficient and costly multi-step processes
Solution Approach 1:
The patent merges multiple process steps into a single laser cutting operation. The laser system can simultaneously create divisions, separations, holes, and complex geometries in one pass, eliminating the need for multiple chemical etching steps, rinsing, drying, and post-processing operations.
Solution Approach 2:
The laser cutting process replaces the complex chemical etching workflow with a single, controlled, digital-based manufacturing process. This substitution dramatically simplifies the fabrication process, improves productivity, and reduces both direct and indirect costs associated with chemical handling and waste management.
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 approach simplifies the fabrication process, reduces costs, and enables more precise and efficient production of IC packages with tighter tolerances, facilitating miniaturization and cleaner singulation without the need for mechanical cutting tools like saws.
Implementation Method 1
laser-cutting the incomplete lead frame portion to provide the completed lead frame sheet
Implementation Method 2
laser-cutting... to create three-dimensional step features and through-holes
Data Source
AI summary
One example described herein includes a method for fabricating integrated circuit (IC) packages. The method includes providing an incomplete lead frame portion and laser-cutting the incomplete lead frame portion to provide a completed lead frame sheet. The completed lead frame sheet includes through-holes and three-dimensional step features. The method further includes coupling a plurality of IC dies to the completed lead frame sheet and coupling the completed lead frame sheet and the IC dies to packaging material to form an IC package block comprising the IC packages.