Routable Trace IC Packaging via Overmold Recess
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Solution Overview
Problem
Modern electronics require integrated circuit packaging systems that offer lower cost, smaller size, and increased functionality while reducing physical dimensions, but existing technologies have not adequately addressed these needs, leading to ongoing challenges in cost reduction, size minimization, and functional enhancement.
Innovation Solution
The proposed solution involves a method of manufacturing an integrated circuit packaging system using a leadframe with a conductive layer and an overmold recess, where an overmold layer is formed within the recess, and the lead pads and routable traces are etched to precise depths to control trace height, allowing for precise control over the dimensions of the routable traces and reducing the likelihood of short circuits, thereby enhancing manufacturing yield and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing manufacturing methods and equipment are used, then cost reduction is achieved, but package dimensions cannot be reduced
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming the overmold recess, selectively etching portions of the leadframe, forming the overmold layer, and completing the etch to expose traces. This segmentation allows each step to be optimized independently, enabling cost-effective manufacturing while achieving reduced package dimensions through precise control of each process stage.
Solution Approach 2:
The invention introduces a vertical dimension by forming an overmold recess that extends into the leadframe structure, then filling it with an overmold layer. This dimensional approach allows the package to achieve compact footprint while maintaining necessary trace exposure and electrical connections, thus reducing overall package dimensions without sacrificing manufacturability.
2Ease of manufacture
If trace height is not precisely controlled, then manufacturing is simpler, but short circuits occur reducing yield
Solution Approach 1:
The overmold recess is formed preliminarily before the final etching step, creating a pre-defined cavity that will accommodate the overmold layer. This preliminary action establishes the boundaries and depth control for subsequent etching operations, ensuring that traces are exposed at the correct height while maintaining manufacturing simplicity through a systematic multi-step process.
Solution Approach 2:
The overmold layer acts as an intermediary element between the leadframe structure and the final trace exposure. It fills the recess, provides mechanical support, and serves as a reference plane that enables precise control of trace height during the etching process, thereby improving yield without significantly complicating manufacturing.
3Volume of moving object
If package size is reduced, then space requirements are met, but manufacturing precision requirements increase
Solution Approach 1:
The invention applies local quality by selectively etching specific portions of the leadframe while leaving other portions intact. The overmold recess is formed at specific locations, and the etching process is localized to expose only the necessary trace portions. This localized precision approach enables compact package design while maintaining high manufacturing precision where it is most critical.
Solution Approach 2:
The invention replaces traditional mechanical trace protection methods with a chemical etching process controlled by the overmold layer geometry. Instead of using mechanical masks or protective fixtures that require high positioning precision, the chemical etching process uses the overmold layer as a self-aligning reference, reducing the overall manufacturing precision requirements while achieving compact package dimensions.
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 results in improved manufacturing yield, reduced error rates, and increased reliability by providing precise control over trace height and conductivity, while also addressing the challenges of cost reduction and size minimization in integrated circuit packaging systems.
Implementation Method 1
a leadframe with a conductive layer on a leadframe active side for protecting a lead pad and a routable trace
Implementation Method 2
etching a portion of the leadframe between the lead pad and the routable trace to expose the overmold layer
Data Source
AI summary
A system and method of manufacture of an integrated circuit packaging system includes: a leadframe with a conductive layer on a leadframe active side for protecting a lead pad and a routable trace, the leadframe having an overmold recess at a leadframe inactive side; an overmold layer in the overmold recess, the overmold layer exposed between the lead pad and the routable trace for forming the lead pad and routable trace; an encapsulation directly on the conductive layer, the lead pad, the routable trace, and the overmold layer; and an external interconnect at the leadframe inactive side.