Kelvin Contact Assembly Tolerance Reduction
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Solution Overview
Problem
Current Kelvin contact assemblies for integrated circuit testing face challenges due to accumulated tolerances, leading to structural weakness, breakage, and difficulty in fine pitching, especially with the ever-smaller contact pads of latest IC chips, resulting in test failures and downtime.
Innovation Solution
A Kelvin contact assembly design that eliminates the use of screws, adhesives, or welding by employing rows of contacts with specially designed protrusions that fit snugly into openings on plate-like layers, creating a sandwich structure with negligible tolerances, allowing precise probing and reducing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional manufacturing methods with cutting tools are used to assemble contacts, then the assembly process is straightforward, but accumulated tolerances increase leading to large overall tolerance and test failures
Solution Approach 1:
The contact assembly is divided into multiple modular sub-assemblies, each containing a contact element mounted on an insulator substrate. These sub-assemblies are then assembled together using a fixture that references a master datum, preventing tolerance accumulation across the entire assembly. Each module can be manufactured separately with standard tolerances, then precisely positioned during final assembly.
Solution Approach 2:
The patent replaces traditional mechanical cutting tool assembly with a fixture-based mechanical positioning system. The fixture uses precision-machined reference surfaces and locators to establish accurate positions for contact elements relative to each other, eliminating the need for cumulative tolerance control through sequential cutting operations.
2Area of stationary object
If part assembly type with thin housing partition wall is used, then the structure is compact, but the partition wall becomes structurally weak and prone to breakage
Solution Approach 1:
The housing partition wall is constructed as a composite structure combining multiple materials or layers to achieve both compactness and strength. This could involve using reinforced plastics, metal inserts, or layered composite materials that provide high strength-to-weight ratio, allowing thin walls to maintain structural integrity while keeping the overall housing compact.
3Area of stationary object
If part assembly type is used, then the assembly is compact, but accumulated tolerances are high making assembly for fine pitching difficult
Solution Approach 1:
The patent employs a precision fixture system with master datum references to replace traditional cumulative tolerance stacking methods. The fixture provides precise mechanical locators and positioning features that ensure accurate spacing and alignment of contact elements, enabling fine pitch assemblies without relying on tight tolerances throughout the entire manufacturing chain.
Solution Approach 2:
The fixture is pre-configured with precision-machined reference surfaces and locators that establish the correct geometry before assembly begins. This preliminary preparation of the assembly fixture ensures that all subsequent components are positioned accurately relative to a common reference, preventing tolerance accumulation and enabling fine pitch configurations.
4Strength
If conventional contact assembly with screws, adhesives or welding is used, then the contacts are securely fastened, but the assembly process is complex and time-consuming
Solution Approach 1:
The patent integrates the contact element mounting directly into the insulator substrate as a unified component, eliminating the need for separate fastening operations. The contact elements are permanently attached to the insulator during substrate manufacturing, combining what were previously separate steps (contact fabrication, insulator fabrication, and fastening) into a single integrated process.
Solution Approach 2:
The contact elements and insulator substrate are designed to self-align and self-secure during assembly through precision-machined mating features. The fixture provides locators that automatically position components correctly, and the design incorporates features that maintain contact pressure and alignment without requiring additional fastening operations, allowing the assembly to service itself.
Data Source
AI summary
An electrical Kelvin contact assembly for testing IC testing apparatus that uses an assembly design that reduces the tolerance to a near negligible range. The assembly does not use any screws, dowel pins, adhesives or welding to fasten the electrical contacts to the housing. The design of the assembly uses rows of contacts with specially designed protrusions that sit snugly in openings located on three plate-like layers. These layers contain the contacts in the horizontal plane by securing the protrusions in the opening, as well as in the vertical plane by means of a sandwich between three separate layers. A second contact is slid into back slits formed by the three layers.