Insulation Layer Blocks Leakage Current in Thermal Contact
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Solution Overview
Problem
Electrolytic corrosion on nickel-plated pedestals during electronic element testing due to leakage currents, leading to significant quality issues and rejected units, with existing solutions like automatic tester detection scripts being slow and chrome plating being complicated and prone to failures.
Innovation Solution
Incorporating an electrical insulation arrangement between the metallic thermal contact surface and the chassis electric reference potential to reduce or prohibit current flow, thereby minimizing electrolytic corrosion by creating a barrier that prevents the formation of an electrolytic cell condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nickel plating is used on the pedestal, then the manufacturing process is simple and cost-effective, but electrolytic corrosion occurs due to leakage current
Solution Approach 1:
The patent introduces an intermediary insulation layer between the nickel-plated pedestal and the DUT. This layer acts as a mediator that blocks the leakage current path while allowing thermal contact, thereby preventing electrolytic corrosion without changing the nickel plating itself. The insulation layer includes a first layer and a second layer with different material compositions to optimize both electrical insulation and thermal conductivity.
Solution Approach 2:
The patent changes the electrical and thermal parameters of the contact interface by introducing an insulation layer with specific electrical resistance and thermal conductivity properties. This allows the system to maintain good thermal contact while achieving sufficient electrical insulation to prevent corrosion currents.
2Reliability
If chrome plating is used on the pedestal, then electrolysis corrosion resistance is improved, but the plating process becomes more complicated and prone to failures
Solution Approach 1:
Instead of changing the pedestal plating material, the patent introduces an intermediary insulation layer at the contact interface. This approach achieves the corrosion protection function of chrome plating while maintaining the simplicity of nickel plating on the pedestal itself.
Solution Approach 2:
The contact interface is segmented into multiple functional layers: the nickel-plated pedestal surface, the insulation layer with first and second sub-layers, and the LTIM. This segmentation allows each layer to perform its specific function optimally without compromising the others.
3Reliability
If automatic tester leaked detection script is used to identify leaky tester card, then faulty hardware can be detected, but the detection is too slow and corrosion still occurs
Solution Approach 1:
The patent applies preliminary protective action by pre-installing the insulation layer on the pedestal before testing begins. This prevents corrosion from occurring in the first place, eliminating the need for continuous monitoring and detection during the testing process.
Solution Approach 2:
The insulation layer provides preliminary anti-action against the harmful leakage current by blocking its path before it can cause corrosion. This preventive measure counteracts the corrosive effect before it can manifest, making detection scripts unnecessary.
4Device complexity
If the pedestal is left without protection, then the device structure remains simple, but corrosion gets aggravated over time causing quality issues
Solution Approach 1:
A thin insulation layer is introduced as an intermediary element that adds minimal structural complexity while providing substantial corrosion protection. The layer is applied as a coating rather than a separate component, maintaining the pedestal's integrated structure.
Solution Approach 2:
The insulation layer is applied as a thin film coating on the pedestal surface, similar to a flexible shell that conforms to the underlying structure. This approach adds protection without significant structural complexity or thickness.
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
Significantly reduces electrolytic corrosion and associated staining issues on the device under test, prolongs the life of existing nickel-plated thermal contact members, and avoids the complexity of chrome plating, providing cost-effective corrosion protection.
Implementation Method 1
an electrical insulation arrangement disposed between the metallic thermal contact surface and the chassis electric reference potential to electrically insulate the metallic thermal contact from the chassis electric reference potential
Implementation Method 2
a layer of liquid thermal interface material, LTIM, therebetween during testing
Data Source
AI summary
An apparatus includes a tester chassis connected to a chassis electric reference potential for electrostatic discharge grounding of the tester chassis; a thermal head assembly coupled to the tester chassis, the thermal head assembly having a metallic thermal contact surface; and an electrical insulation arrangement disposed between the metallic thermal contact surface and the chassis electric reference potential to electrically insulate the metallic thermal contact from the chassis electric reference potential. An electrolytic corrosion protection system for the apparatus and a cable assembly for the apparatus.