Semiconductor Lead Frame Slits for Thermal Strain Relief
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Solution Overview
Problem
The challenge is to manufacture a multi-pin semiconductor device using a lead frame while reducing costs, improving reliability, and enhancing quality, particularly addressing issues such as thermal strain-induced deflection of bus bar leads and wire bonding defects in existing lead frame technologies.
Innovation Solution
The solution involves a semiconductor device configuration with bar-like common leads having slits, which are coupled to suspending leads outside the chip mounting portion, allowing for thermal expansion relief and improved rigidity, along with specific manufacturing steps that include wire bonding and resin sealing to prevent wire peeling and shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a lead frame is used to reduce manufacturing cost, then cost is reduced, but thermal strain causes deflection of bus bar leads during wire bonding
Solution Approach 1:
The bus bar lead is divided into multiple segments by forming slits, allowing each segment to independently accommodate thermal expansion and contraction without causing deflection or wire bonding defects
Solution Approach 2:
The physical structure of the bus bar lead is changed by introducing slits, transforming it from a rigid continuous structure to a segmented flexible structure that can absorb thermal strain
2Stability of the object's composition
If bus bar leads are fixed at both ends to suspending leads, then structural stability is improved, but thermal expansion is restricted causing deflection
Solution Approach 1:
The bus bar lead is segmented into multiple sections by slits, allowing the structure to remain stable at connection points while enabling controlled movement and expansion within each segment
Solution Approach 2:
The bus bar lead combines rigid connection points (where fixed to suspending leads) with flexible segmented portions (with slits), creating a composite structure that simultaneously achieves stability and thermal expansion capability
3Adaptability or versatility
If the number of pins is increased for higher performance, then device capability is improved, but device size increases with peripheral lead arrangement
Solution Approach 1:
The bus bar leads serve multiple functions: they provide common electrical connections for multiple pins, act as structural support elements, and function as thermal strain absorption zones, thereby supporting high-pin-count designs without proportionally increasing device size
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 configuration effectively reduces deflection of common leads due to thermal strain, prevents wire peeling, and enhances the reliability and quality of the semiconductor device by ensuring stable wire bonding and uniform resin flow, thereby enabling the production of cost-effective multi-pin devices.
Implementation Method 1
the lead frame is apt to undergo expansion or contraction (thermal strain) under the influence of heat
Data Source
AI summary
A semiconductor device of a multi-pin structure using a lead frame is provided. The semiconductor device comprises a tab having a chip supporting surface, the chip supporting surface whose dimension is smaller than a back surface of a semiconductor chip, a plurality of leads arranged around the tab, the semiconductor chip mounted over the chip supporting surface of the tab, a plurality of suspending leads for supporting the tab, four bar leads arranged outside the tab so as to surround the tab and coupled to the suspending leads, a plurality of wires for coupling between the semiconductor chip and the leads, and a sealing body for sealing the semiconductor chip and the wires with resin, with first slits being formed respectively in first coupling portions of the bar leads for coupling with the suspending leads.