Reflow Connector Cap Structure for Thermal Expansion Relief
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Solution Overview
Problem
High-speed transmission connectors experience housing distortion and solder cracks during reflow mounting due to differences in thermal expansion coefficients between the housing and cap, which are typically made of resin with different molding directions.
Innovation Solution
The connector set includes a cap with a fitted portion and a fitting portion that absorbs thermal expansion through slots and holes, allowing the cap to expand without pressing the housing, thereby preventing distortion and solder cracks. The cap is designed with round and long holes to accommodate positioning pins and absorb thermal expansion, ensuring proper alignment and expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cap and housing are made of resin with different molding directions, then the manufacturing flexibility and design freedom are improved, but the thermal expansion coefficients differ causing housing distortion and solder cracks during reflow
Solution Approach 1:
The connector assembly is segmented into distinct components (housing, cap, positioning pins) with independent thermal expansion characteristics. The positioning pins are separated into round pins (fixed positioning) and long pins (allowing linear expansion), enabling each segment to handle thermal stress differently while maintaining overall assembly integrity during reflow processing.
2Manufacturing precision
If the cap is tightly fitted to the housing, then the structural stability and alignment precision are improved, but the thermal expansion of the cap causes housing distortion and solder cracks
Solution Approach 1:
The positioning mechanism transitions from a static rigid fit to a dynamic system that adapts during thermal cycles. The long positioning pins are designed to move linearly within their slots during heating and cooling, allowing the cap to expand and contract dynamically without transmitting excessive stress to the housing, thus preventing distortion and solder cracks while maintaining alignment precision.
Solution Approach 2:
The design changes the constraint parameters of the positioning system by providing different degrees of freedom for different positioning pins. Round positioning pins maintain fixed radial positioning, while long positioning pins allow linear displacement along the slot direction. This parameter differentiation enables the system to accommodate thermal expansion while preserving manufacturing precision.
3Reliability
If the cap is allowed to expand freely, then the thermal stress on the housing is reduced, but the alignment and positioning accuracy deteriorate
Solution Approach 1:
The long positioning pins act as intermediaries between the cap and housing, mediating the thermal expansion process. These pins are fitted into slots that guide their movement, allowing them to absorb expansion forces while maintaining positional relationship. This intermediary mechanism reduces thermal stress on the housing while preserving alignment accuracy through controlled movement paths.
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 design effectively prevents housing distortion and solder cracks during reflow mounting by managing thermal expansion, ensuring reliable electrical connections and preventing reverse insertion errors.
Implementation Method 1
the fitted portion is provided with an opening portion for moving the fitting portion so as to absorb thermal expansion from one end portion side to the other end portion side due to temperature conversion of reflow
Data Source
AI summary
A connector set is disclosed that includes a plurality of connectors and a cap to be attached to the plurality of connectors when the plurality of connectors are reflow-mounted on an external substrate. Each one end portion of the connectors and the cap is provided with a fitted portion and a fitting portion to be fitted in the fitted portion. The fitted portion is provided with an opening portion for moving the fitting portion so as to absorb thermal expansion from one end portion side to the other end portion side due to temperature conversion of reflow.