Leadframe Spacer Structure for Stable Wire Bonding and Coplanarity
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Solution Overview
Problem
Semiconductor manufacturing processes often compromise between cost reduction and product performance and reliability, particularly during wire bonding operations where leadframe flexibility can lead to reduced yields and reliability.
Innovation Solution
A semiconductor device with a leadframe spacer structure, where a non-conductive, rigid spacer is attached to the inner portion of half-etched leads using an adhesive, providing reinforcement and support during manufacturing, ensuring the leads' stability and alignment with the encapsulant's bottom surface, thus enhancing reliability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If leadframe flexibility is increased to reduce manufacturing costs, then ease of manufacture is improved, but reliability and yield during wire bonding deteriorate
Solution Approach 1:
The leadframe is segmented into different thickness regions: a first thickness portion and a second thickness portion. This segmentation allows different sections of the leadframe to have different mechanical properties, enabling cost-effective manufacturing while maintaining reliability in critical bonding areas.
Solution Approach 2:
Different portions of the leadframe are given different local qualities through varying thickness. The first thickness portion provides flexibility for manufacturing, while the second thickness portion provides rigidity and reliability for wire bonding operations. This local differentiation resolves the contradiction between ease of manufacture and reliability.
2Loss of substance
If leadframe thickness is reduced to lower costs, then manufacturing cost is reduced, but structural integrity and support during wire bonding worsen
Solution Approach 1:
The leadframe structure is divided into thickness portions, allowing material reduction in non-critical areas while maintaining sufficient material in bonding-critical areas. This segmentation enables cost reduction through reduced material usage without compromising structural integrity where needed.
Solution Approach 2:
The leadframe exhibits local quality variations in thickness to optimize material usage. Thinner sections reduce material cost and weight, while thicker sections provide the structural integrity and support necessary for reliable wire bonding, thus resolving the contradiction between material reduction and strength maintenance.
3Ease of manufacture
If uniform leadframe thickness is used to simplify manufacturing, then ease of manufacture is improved, but coplanarity with encapsulant bottom surface deteriorates
Solution Approach 1:
The leadframe is segmented into different thickness portions that can be selectively positioned to achieve coplanarity with the encapsulant bottom surface. This segmentation allows manufacturing processes to account for variations and achieve precise coplanarity outcomes.
Solution Approach 2:
Different local thickness qualities in the leadframe enable precise control over the coplanarity relationship with the encapsulant. By varying thickness locally, the design achieves manufacturing precision in the coplanarity parameter while maintaining ease of manufacture through standardized processes.
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 leadframe spacer structure improves the reliability and yield of semiconductor devices by reinforcing the leads during wire bonding and ensuring coplanarity with the encapsulant, facilitating better connection and thermal dissipation, and maintaining the structural integrity of the device.
Implementation Method 1
The spacer structure is attached at a bottom side of the inner portion of the leads by way of an adhesive material
Data Source
AI summary
A method of manufacturing a semiconductor device is provided. The method includes affixing a spacer structure to a bottom side of a plurality of leads of a leadframe. A semiconductor die is attached to a top side of a die pad of the leadframe. The semiconductor die, the leadframe, and the spacer structure are encapsulated with an encapsulant. Portions of the spacer structure and portions of the leads of the plurality of leads are exposed at a bottom side of the encapsulant.