Contact Probe Segmentation for Reliable Semiconductor Socket Testing
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Solution Overview
Problem
Existing contact probes face challenges in achieving high accuracy in forming deep cavities with thin walls, uniform plating, and stable contact due to miniaturization, leading to difficulties in ensuring good conductivity and smooth operation.
Innovation Solution
A contact probe design featuring a first plunger, a second plunger, and a coil spring with a guide portion that guides the contact stem portion to ensure reliable contact, eliminating the need for deep guiding holes and allowing for easier processing and plating, while maintaining sufficient strength and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep cavity is provided in the barrel to ensure engagement of the contact tip end portion, then contact reliability is improved, but manufacturing precision deteriorates due to difficulty in forming deep cavities with thin walls at high accuracy
Solution Approach 1:
The contact probe is divided into two separate plungers (first plunger with contact stem portion and second plunger with contact portion) that make contact with each other, eliminating the need for a deep cavity in the barrel. This segmentation allows both components to be manufactured independently with standard precision, avoiding the manufacturing difficulties of forming deep thin-walled cavities.
Solution Approach 2:
Instead of having the contact tip end portion inserted into a deep cavity in the barrel as in conventional designs, the invention inverts the contact structure by having the contact stem portion of the first plunger make direct contact with the contact portion of the second plunger, with the coil spring providing the engagement mechanism rather than a fixed cavity.
2Volume of moving object
If the barrel is miniaturized to reduce contact probe size, then device miniaturization is achieved, but plating uniformity deteriorates due to difficulty in circulating plating solution inside deep cavities
Solution Approach 1:
By segmenting the contact structure into two plungers without a deep barrel cavity, the plating solution can freely access all conductive surfaces during the plating process. The simplified structure eliminates the deep narrow cavity that hindered plating solution circulation, enabling uniform plating even as the overall probe size is reduced.
3Reliability
If clearance between the cavity and contact tip end portion is reduced to improve contact property, then conductivity is improved, but mechanical smoothness deteriorates as the barrel and plunger do not travel smoothly
Solution Approach 1:
The contact structure is segmented into two separate plungers that move independently within their own housings. The first plunger moves within the barrel while the second plunger is pressed by the coil spring, allowing both to travel smoothly in their respective spaces without the clearance issues that would arise from reducing clearance in a single-cavity design.
Solution Approach 2:
The coil spring acts as an intermediary element between the first and second plungers, providing the necessary contact force while allowing both plungers to move smoothly in their own spaces. The spring compresses and expands to maintain contact without requiring tight clearances between moving parts.
4Volume of moving object
If the contact probe is miniaturized to reduce size, then device compactness is improved, but manufacturing difficulty increases due to extreme difficulty in forming deep cavities with thin walls at high accuracy
Solution Approach 1:
The contact probe structure is segmented into two separate plungers without a deep cavity in the barrel, eliminating the manufacturing step of forming deep thin-walled cavities. Each plunger can be manufactured using standard precision processes, significantly easing manufacturing difficulty while maintaining the miniaturized form factor.
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 design enables reliable conduction, improved production yield, and reduced resistance, while preventing issues like entanglement and adhesion during plating, ensuring high-reliability inspection and reduced temperature rise during current application.
Implementation Method 1
a coil spring connected to the first plunger and the second plunger in such a way as to cover the contact stem portion
Data Source
AI summary
The invention provides a contact probe and a semiconductor element socket provided with the same, the contact probe capable of smooth inspection of a device while securing good conductivity. A contact probe has an upper plunger having a contact stem portion, a lower plunger having an insertion hole with which the contact stem portion is capable of coming into contact, and a coil spring connected to the upper plunger and the lower plunger in such a way as to cover the contact stem portion. The coil spring is configured by helically winding a wiring, and includes a guide portion wound tight in the axial direction of the coil spring by the wire, the guide portion located on the lower plunger side of the coil spring and also includes the upper plunger side portion than an upper end portion of the insertion hole.