Lead Bending Punch Gap Control for Semiconductor Devices
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Solution Overview
Problem
Conventional lead forming processes for semiconductor devices face issues such as scratches and peeling of solder plating due to clamping between dies, and require complex and costly precision machining to adjust lead geometry, leading to increased production time and cost.
Innovation Solution
A lead forming apparatus with a mechanism to adjust the bottom dead center of the lead bending punch, ensuring a gap not smaller than the lead thickness between the punch and die, allowing for adjustable lead geometry without re-designing die components, reducing contact area and preventing scratching or peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If leads are clamped between dies during bending process, then leads can be formed into predetermined geometry, but scratches and peeling of solder plating occur
Solution Approach 1:
The die is divided into two functional portions: a first portion that contacts and forms the lead, and a second portion that does not contact the lead. This segmentation allows the lead to be formed into the desired geometry while avoiding unnecessary contact that causes scratches and plating peeling.
Solution Approach 2:
Different portions of the die have different functional properties. The first portion is designed to contact and form the lead with appropriate geometry, while the second portion is designed to avoid contact with the lead entirely. This local differentiation of function resolves the contradiction between achieving precise lead geometry and preventing solder plating damage.
2Manufacturing precision
If dies are designed with same geometry as leads, then leads can be formed accurately, but die components require complicated and precision machining
Solution Approach 1:
The die is segmented into a first portion that defines the lead geometry and a second portion that does not contact the lead. This segmentation simplifies the overall die design by reducing the amount of precision machining required, while still achieving accurate lead geometry formation through the first portion.
Solution Approach 2:
Instead of designing the entire die with the same geometry as the lead (which complicates manufacturing), the invention inverts the approach by designing only the necessary first portion to contact and form the lead, while the second portion is designed to avoid contact. This inversion simplifies die manufacturing while maintaining lead formation accuracy.
3Productivity
If leads are clamped between dies, then bending can be performed, but debris accumulates in dies causing excessive local pressure
Solution Approach 1:
The second portion of the die is designed to not contact the lead, which extracts or removes the source of debris accumulation. By eliminating unnecessary contact areas, the invention prevents debris from accumulating in the die, thereby avoiding excessive local pressure and maintaining productive lead forming operations.
Data Source
AI summary
A lead forming apparatus has a function of bending leads of a semiconductor device having leads into a gull wing shape. The lead forming apparatus includes: a lead bending die, as a lower die, allowing thereon placement of the semiconductor device and accepting the leads in the bending leads; a lead bending punch, as an upper die, descending towards the lead bending die so as to move the leads of the semiconductor device towards the lead bending die, to thereby bend the leads into a gull wing shape; and a first stopper specifying the bottom dead center of the lead bending punch, so as to ensure a distance not smaller than thickness of the leads between the bottom surface of the lead bending punch and the top surface of a portion, allowing thereon placement of the leads, of the lead bending die.