Leadframe Hole-Defining Walls Distribute Stress

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional leadframes are prone to deformation and bending due to stress accumulation from uniform punching direction, leading to undesired bends during the formation of through holes.

Innovation Solution

A leadframe design with alternately disposed first and second hole-defining wall groups, punched in opposite directions to form first and second through holes, distributing stress evenly and preventing bending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If all through holes are formed by punching the substrate in the same punching direction, then the manufacturing process is simple and efficient, but the leadframe accumulates stress and deforms resulting in undesired bends

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidstructural stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The through holes are segmented into two groups: first through holes formed by punching in a first direction, and second through holes formed by punching in a second direction opposite to the first direction. This segmentation of the punching process into two directional stages allows stress distribution while maintaining manufacturing efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The punching directions for different through hole groups are made asymmetric - first through holes are punched in one direction while second through holes are punched in the opposite direction. This asymmetric approach to an otherwise uniform process prevents stress accumulation and deformation.

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If the substrate is punched in a single direction to form all through holes, then the manufacturing process is straightforward, but stress accumulates causing leadframe deformation

Engineering Contradiction:

Improveprocess simplicityVSAvoiddimensional accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The punching operation is divided into two sequential segments: first punching through holes in one direction, then punching through holes in the opposite direction. This segmented approach maintains process simplicity while achieving dimensional accuracy by preventing stress accumulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of punching all holes in the same direction, the patent inverts the punching direction for the second group of through holes. This inversion of the conventional approach allows stress to be distributed in opposite directions, preventing deformation while keeping the process straightforward.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS10600726B2Leadframe and method of making the same

Publication Date: 2020.03.24 CHANG WAH TECH

AI summary

A leadframe includes first and second surfaces, a plurality of leads, and a hole-defining wall unit including a plurality of first-hole defining walls each defining a first through hole and a plurality of second-hole defining walls each defining a second through hole. Each of the first and second through holes is formed between two adjacent ones of the leads. Each of the first hole-defining walls has top and bottom edges respectively forming arcuate and burr regions with the first and surfaces at junctions therebetween. Each of the second hole-defining walls has top and bottom edges respectively forming burr and arcuate regions with the first and second surfaces at junctions therebetween.