Lead Frame Outer Lead Structure for Consistent Bend Profiles
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Solution Overview
Problem
Conventional semiconductor devices using lead frames suffer from variant shapes in outer leads due to dam bar cut-off portions, leading to undesired acute profiles during bending, which can affect electrical connectivity and reliability.
Innovation Solution
The semiconductor device employs a conductive support member with specific lead configurations, including first and second outer leads with defined divisions and bends, and inner leads covered by a sealing resin, ensuring consistent lead shapes and reliable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dam bars are cut to separate outer leads, then leads can be separated for individual use, but variant shapes and acute profiles occur after bending
Solution Approach 1:
The patent applies preliminary action by forming rounded corners at the cut-off portions of the dam bar before the cutting operation. This pre-shaping ensures that when the leads are subsequently bent, the rounded corners prevent the formation of acute profiles and maintain consistent lead shapes. The rounding is performed as a preparatory step that anticipates and prevents the shape variation problem that would otherwise occur during bending.
2Ease of manufacture
If outer leads have greater width at cut-off portions, then separation is achieved, but acute profiles are produced during bending
Solution Approach 1:
The patent applies local quality by modifying only the specific regions where cut-off portions are formed, giving these locations rounded corners while leaving the rest of the lead structure unchanged. This localized treatment at the critical cut-off portions prevents acute profiles during bending without affecting the overall lead geometry or the separation functionality. The rounding is applied precisely where needed to solve the manufacturing precision issue.
Data Source
AI summary
The semiconductor device includes a semiconductor element, a conductive support member and a sealing resin whose resin side surface faces one side of a first direction. The support member has an outer lead including a root portion extending from the resin side surface, a mount portion on one side of a thickness direction relative to the root portion, and an extended portion connected to the root portion via a bent portion and to the mount portion via another bent portion. The outer lead has a first division including the extended portion, a second division including the root portion and connected to the first division, and a third division including the mount portion and connected to the first division. The first division is greater in second-direction dimension than the second and third divisions. A division boundary between the first and the third divisions is at the extended portion.