Probe Surface Layer Shield Region Solder Control
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Solution Overview
Problem
The high electrical resistance of blade-type probes made from flexible metal materials, such as nickel and its alloys, leads to inaccurate repeatability of rectangular wave signals during electrical testing, and the rolled gold layer used to reduce resistance causes excessive solder spread, complicating stable bond formation between probes and the support base plate.
Innovation Solution
A probe design featuring a surface layer with higher conductivity and wettability than the probe body, including a shield region with lower solder wettability near the base end to prevent excessive solder spread, ensuring a proper fillet shape and stable bond strength, and using materials like gold for the surface layer and nickel alloys for the probe body and shield region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rolled gold layer is used to reduce electrical resistance, then conductivity is improved, but solder wettability increases causing excessive solder spread
Solution Approach 1:
The probe structure applies different surface properties to different regions: the side surface and top surface have high solder wettability for good electrical connection, while the bottom surface has low solder wettability to prevent excessive solder spread. This local differentiation of surface properties resolves the contradiction between achieving good electrical contact and controlling solder flow during assembly.
2Strength
If a highly tenacious metal material is used for the probe body, then mechanical strength is improved, but electrical resistance increases reducing signal accuracy
Solution Approach 1:
The probe is constructed as a composite structure with a nickel-based alloy body providing mechanical strength and flexibility, combined with a rolled gold layer on the side and top surfaces providing low electrical resistance. This composite approach allows the probe to simultaneously achieve high mechanical tenacity for reliable contact and low electrical resistance for accurate signal transmission.
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 probe assembly achieves stable solder bond strength and efficient soldering by controlling solder spread, allowing for accurate electrical testing and durable engagement with semiconductor electrodes.
Implementation Method 1
a surface layer showing a conductivity higher than the conductivity of the probe body and a solder wettability higher than the wettability of the probe body, and extending on the surface of the probe body from the base end to the front end
Implementation Method 2
in the vicinity of the base end of the surface layer, a shield region is formed across the surface layer, the shield region having a smaller solder wettability than that of the surface layer
Data Source
AI summary
A probe for electrical test comprises a probe body having a base end attached to a support base plate through a solder and a front end continuous with said base end and a surface layer showing a conductivity higher than that of the probe body and a solder wettability higher than that of the probe body and extending on the surface of the probe body from the base end to the front end. In the vicinity of the base end of the surface layer, a shield region having a smaller solder wettability than that of the surface layer is formed across the surface layer.