Symmetrical Electrical Contact Profiles for SMT Alignment
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Solution Overview
Problem
During the solder reflow process in Surface Mount Technology (SMT), molten solderable material can cause misalignment of discrete components in socket assemblies relative to the circuit board due to wicking or wetting of electrical contact surfaces, leading to solder joint defects and failure in electrical contact.
Innovation Solution
The design of electrical contacts with specific profiles, including a leg, foot, heel, and toe portions, where the heel and toe portions have symmetrical profiles to equally wet the solderable material during reflow, preventing movement and maintaining alignment with the circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solder reflow process is used to form solder joints between socket assembly components and circuit board, then reliable electrical contact is achieved, but misalignment occurs causing solder joint defects
Solution Approach 1:
The patent applies preliminary action by pre-positioning the socket assembly components on a temporary carrier substrate before the solder reflow process. This preliminary positioning ensures precise alignment is established before soldering begins, preventing misalignment during the reflow process while still achieving reliable electrical contact through the subsequent solder joint formation.
2Reliability
If discrete components are coupled with circuit board using solder joints, then electrical connectivity is achieved, but repositioning occurs during reflow process
Solution Approach 1:
The patent implements preliminary action by establishing the precise spatial arrangement of discrete components on a carrier substrate before the solder reflow process. This pre-positioning ensures component position stability is maintained during reflow, while electrical connectivity is achieved through the subsequent solder joint formation between the pre-positioned components and the circuit board.
3Reliability
If molten solderable material wets electrical contact surfaces, then solder joints are formed, but misalignment between socket assembly and circuit board occurs
Solution Approach 1:
The patent applies preliminary action by pre-establishing the precise alignment between socket assembly components and the circuit board on a carrier substrate before the solder reflow process. This preliminary alignment ensures that when molten solderable material wets the electrical contact surfaces, the components remain properly positioned, achieving reliable solder joint formation without misalignment.
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
This configuration effectively mitigates misalignment issues during solder joint formation, ensuring reliable electrical contact and reducing solder joint defects by controlling the center of mass of the solderable material, thus maintaining precise positioning of socket assembly components.
Implementation Method 1
molten solderable material may wick or wet the electrical contact surfaces of the socket assembly or circuit board
Implementation Method 2
the heel and toe portions have symmetrical profiles to equally wet the solderable material during reflow, preventing movement
Data Source
AI summary
Embodiments of the present disclosure are directed towards techniques and configurations to control movement and position of surface mounted electrical devices. In one embodiment, an electrical contact includes a leg portion configured to extend in a first direction, a foot portion coupled with the leg portion, the foot portion having a surface that extends in a second direction that is substantially perpendicular to the first direction, the surface being configured to directly couple with solderable material to form a solder joint, a heel portion adjoining the leg portion and the foot portion, the heel portion having a profile shape, and a toe portion extending from the foot portion and disposed opposite to the heel portion, the toe portion having a profile shape that is symmetric with the profile shape of the heel portion. Other embodiments may be described and/or claimed.