Insulative Pusher Pin for Uniform Force Distribution
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Solution Overview
Problem
Conventional automatic test equipment for chip packages faces challenges in uniformly applying force due to height differences, leading to potential damage and poor testing results, especially in lidless chip packages with varied die heights.
Innovation Solution
The use of electrically insulative pusher pins with a spring mechanism and wide, insulative tips that distribute force over a larger area, preventing short circuits and reducing pressure on the chip packages, thereby minimizing the risk of damage and ensuring accurate testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional aluminum workpress is used to apply force to the chip package, then the workpress can be easily manufactured, but the force is not uniformly distributed due to height differences, causing damage and poor testing results
Solution Approach 1:
The workpress is segmented into multiple individual pusher pins rather than a single continuous surface. Each pin can independently contact the chip package at its highest point, accommodating height variations across different regions of the package without requiring precise uniformity across the entire contact surface.
Solution Approach 2:
Each pusher pin is designed with a spherical contact tip that provides point contact with the chip package. This local spherical geometry allows each pin to adapt to the local height variations at its specific contact location, ensuring uniform force distribution despite global height differences across the package.
2Device complexity
If pusher pins with small contact area are used, then the pin structure is simple, but the pressure on the chip package is too high, causing delamination and cracks
Solution Approach 1:
The pusher pin incorporates a flexible spring mechanism that allows the pin to deflect and adapt to height variations. The spring acts as a compliant element that distributes the applied force more evenly across the contact interface, reducing peak pressures that would cause damage to the chip package.
3Reliability
If conductive pusher pins are used for testing, then electrical connection can be established, but short circuits may occur due to height differences causing uneven force distribution
Solution Approach 1:
An electrically insulating coating is applied to the pusher pin, creating an intermediary layer between the conductive pin body and the chip package. This insulating layer prevents electrical short circuits while allowing the pin to maintain mechanical contact and apply force uniformly across the package surface.
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 solution allows for uniform force distribution across the chip package, reducing the risk of delamination and cracks, while preventing short circuits, thus ensuring reliable and safe testing of integrated circuit packages.
Implementation Method 1
The spring disposed between the first ends of the first and second plunger members and biases the exposed second end of the first plunger member away from the exposed second end of the second plunger member
Data Source
AI summary
An electrically insulative pusher pin is disclosed. In one example, an electrically insulative pusher pin includes a first plunger member, a second plunger member, and a spring. The first plunger member has a first end and an exposed second end. The second plunger member has a first end and an exposed second end. The second plunger member is movable relative to the first plunger member, where the exposed second ends of the first and second plunger members defining a length of the pusher pin. The spring disposed between the first ends of the first and second plunger members and biases the exposed second end of the first plunger member away from the exposed second end of the second plunger member. An electrically insulative path is defined between the exposed second end of the first plunger member and the exposed second end of the second plunger member through the pusher pin.