Lead Frame Monolithic Connector for Longer Leads
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Solution Overview
Problem
Semiconductor packages face limitations in lead length due to structural weakness beyond 2 mm, and manufacturing errors can cause gaps between support kits and leads during wire bonding, leading to shaking or deformation.
Innovation Solution
A lead frame design featuring a die paddle surrounded by leads with an integrated connector and bonding layer, allowing for longer lead lengths and eliminating gaps through a monolithic structure and etching process, which enhances structural strength and prevents deformation during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the length of the lead is increased to ensure proximity to smaller semiconductor dies and prevent excessive bonding wire length, then the lead length is improved, but the structural strength of the lead deteriorates due to weakness beyond 2 mm
Solution Approach 1:
The lead structure is divided into multiple segments: the lead body, the bonding end, and the support kit. This segmentation allows the lead to maintain adequate length for smaller semiconductor dies while distributing structural load across multiple components, thereby preventing excessive wire length without compromising overall structural strength.
Solution Approach 2:
The support kit acts as an intermediary component that reinforces the bonding end of the lead. It provides additional structural support at the critical bonding region, enabling the lead to achieve greater length while maintaining sufficient strength through the reinforced bonding end structure.
2Stability of the object's composition
If a support kit is added to support bonding ends of leads and prevent shaking or deformation during wire bonding, then the stability of leads is improved, but manufacturing errors cause dimension errors of the support kit and leads, generating gaps that fail to prevent shaking
Solution Approach 1:
The support kit and lead are merged into a single monolithic structure formed by the etching process. This integration eliminates the interface between separate components, ensuring precise dimensional alignment and preventing gaps that would occur with separately manufactured parts. The unified structure guarantees consistent dimensional relationships regardless of manufacturing variations.
Solution Approach 2:
The monolithic structure serves multiple functions simultaneously: it provides structural support, defines precise dimensional relationships, and ensures proper alignment. This multi-functionality eliminates the need for separate support components while maintaining stability during wire bonding, as the single structure performs both support and positioning functions with inherent precision.
3Strength
If the lead length is constrained to less than or equal to 2 mm to maintain structural strength, then the structural strength is preserved, but the lead cannot be near smaller semiconductor dies and the bonding wire becomes longer than optimum
Solution Approach 1:
The solution extends the lead structure in the vertical dimension by incorporating the support kit that protrudes from the lead body. This allows the horizontal lead length to remain constrained for strength while the vertical support structure provides the necessary positioning and support function, effectively adding length in a different dimension without compromising structural integrity.
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 enables longer lead lengths without structural weakness and eliminates manufacturing errors, ensuring stable wire bonding and improved reliability by integrating the connector with the lead frame as a monolithic structure, thus preventing shaking or deformation.
Implementation Method 1
forming a bonding layer to cover a portion of the metal plate and expose a portion of the metal plate... the bonding layer is formed on a lower surface of the die paddle and a lower surface of each of the outer lead portions
Implementation Method 2
etching the exposed portion of the metal plate to form a lead frame... each of the leads includes an inner lead portion adjacent to and spaced apart from the die paddle and an outer lead portion opposite to the inner lead portion
Data Source
AI summary
A lead frame includes a die paddle, a plurality of leads, at least one connector and a bonding layer. The leads surround the die paddle. Each of the leads includes an inner lead portion adjacent to and spaced apart from the die paddle and an outer lead portion opposite to the inner lead portion. The connector is connected to the die paddle and the inner lead portions of the leads. The bonding layer is disposed on a lower surface of the die paddle and a lower surface of each of the outer lead portions.