Multi-Stage Molding Protects Wirebonds in IC Packages
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Solution Overview
Problem
The fragility of wirebonds in integrated circuits is compromised during the molding process due to pressurized plastic flow, leading to damage and inefficiencies in the manufacturing of IC packages.
Innovation Solution
A two-stage molding process is employed, where a first mold material is applied to protect the wirebonds, allowing a second mold material to be applied at higher pressures without damaging the connections, using materials with compatible coefficients of expansion to ensure integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage molding process is used with high pressure to efficiently encapsulate the IC package, then productivity is improved, but the wirebonds are damaged due to the pressurized flow of plastic material
Solution Approach 1:
The molding process is divided into two distinct stages: a first molding step that applies material at lower pressure to encapsulate the wirebonds and die, followed by a second molding step that applies additional material at higher pressure to complete the package encapsulation. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between productivity and wirebond integrity.
Solution Approach 2:
The first molding step performs a preliminary encapsulation of the wirebonds and die before the second molding step. By protecting the wirebonds in advance with the first mold material, the system enables the second stage to apply high pressure without damaging the delicate connections, thus maintaining both reliability and productivity.
2Productivity
If high pressure is applied during molding to improve manufacturing efficiency, then productivity increases, but wirebond damage occurs reducing yield
Solution Approach 1:
The molding operation is segmented into two pressure stages: a low-pressure first molding step that protects the wirebonds, and a high-pressure second molding step that improves efficiency. This segmentation resolves the contradiction by applying appropriate pressure levels at different stages of the manufacturing process.
Solution Approach 2:
The first molding step performs a preliminary protective encapsulation of the wirebonds at low pressure, establishing a protective barrier before the high-pressure second molding step. This preliminary action ensures wirebond integrity is maintained while still allowing efficient high-pressure molding to follow.
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 significantly reduces wirebond damage and improves yield by protecting delicate connections during the molding process, enabling higher pressure applications without compromising the integrity of the wirebonds.
Implementation Method 1
applying a first mold material over at least a portion of the wirebond and the die and the leadfinger to form an assembly
Implementation Method 2
waiting for the first mold material to at least partially cure
Implementation Method 3
applying a second mold material over the assembly
Data Source
AI summary
Methods for providing an integrated circuit using a multi-stage molding process to protect wirebonds. In one embodiment, a method includes attaching a die to a leadframe having a lead finger, attaching a wirebond between the die and the leadfinger, applying a first mold material over at least a portion of the wirebond and the die and the leadfinger to form an assembly, waiting for the first mold material to at least partially cure, and applying a second mold material over the assembly.