Lead Frame Assembly Clip Support for Thermal Mass
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Solution Overview
Problem
In semiconductor devices, rotational or tilting misplacement of clip frames relative to the semiconductor die during mounting and attachment can occur due to non-uniform bond line thickness caused by increased clip thickness for enhanced thermal mass, leading to reduced functionality or failure, and potential damage from mechanical removal of mould flashing.
Innovation Solution
A lead frame assembly comprising a die attach structure and a clip frame structure with orthogonally arranged clip support members and a lead supporting member to maintain the clip frame parallel to the semiconductor die, preventing tilting and ensuring uniform bond line thickness, and a heat sink member for increased thermal mass without exposing the clip frame through the moulding material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the clip material is increased to increase thermal mass, then the heat sink capability is improved, but the downward pressure on the solder or conductive adhesive increases causing non-uniform bond line thickness and tilting
Solution Approach 1:
The clip frame structure is divided into multiple functional segments: a heat sink portion with increased thickness for thermal mass, and multiple support members (first and second support members) that extend to contact the die attach structure. This segmentation allows the heavy heat sink portion to be supported at multiple points, distributing the downward pressure and maintaining uniform bond line thickness across the bonding area.
Solution Approach 2:
The support members act as intermediary elements between the heavy clip frame structure and the die attach structure. These support members transfer and distribute the weight of the thick clip frame, preventing excessive localized pressure on the bonding material and maintaining parallel alignment between the clip frame and semiconductor die.
2Quantity of substance
If the thickness of the clip material is increased, then the thermal mass is improved, but the weight increases causing increased downward pressure and tilting
Solution Approach 1:
The clip frame structure is segmented into a heat sink portion that provides thermal mass and support members that manage the weight distribution. By separating these functions into distinct structural elements, the design achieves high thermal mass without allowing the entire structure to exert excessive localized pressure on the bonding interface.
3Ease of manufacture
If mechanical forces are used to remove excessive mould flashing, then the mould flashing is removed, but the moulding material may separate from the semiconductor die and lead frame causing failure
Solution Approach 1:
The clip frame structure is designed with support members that maintain proper alignment and parallelism during the moulding process itself. This preliminary structural control prevents excessive mould flashing from forming in the first place, eliminating or reducing the need for post-moulding mechanical removal operations that could damage the device.
4Shape
If the clip frame structure is tilted, then one end is higher than the other, but this causes mould compound to enter gaps between the top of mould cavity and the clip
Solution Approach 1:
The support members provide continuous structural feedback during assembly and moulding, maintaining the clip frame in a parallel orientation to the semiconductor die. This real-time structural constraint prevents tilting that would create gaps allowing mould compound contamination, ensuring proper alignment throughout the manufacturing process.
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
The solution effectively prevents tilting of the clip frame, maintains uniform bond line thickness, reduces the need for mechanical post-processing to remove mould flashing, and enhances heat dissipation while ensuring the semiconductor device's reliability and functionality.
Implementation Method 1
the conductive clip material may have increased thermal mass compared to the wire bond material and can thus act as a heat sink for the semiconductor die
Data Source
AI summary
The disclosure relates to a lead frame assembly for a semiconductor device, the lead frame assembly including: a die attach structure and clip frame structure. The clip frame structure includes: a die connection portion configured to contact to one or more contact terminals on a top side of the semiconductor die; one or more electrical leads extending from the die connection portion at a first end, and a lead supporting member extending from a second end of the one or more leads; and a plurality of clip support members arranged orthogonally to the one or more electrical leads. The plurality of support members and the lead supporting member are configured to contact the die attach structure. The present disclosure also relates a die attach structure and clip frame structure for a semiconductor device, a semiconductor device including the same and a method of manufacturing the semiconductor device.