Semi-Aromatic Polyamide E/E Connector Blister Resistance
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Solution Overview
Problem
Conventional polyamide compositions used in electrical/electronic connectors suffer from blistering issues during high-temperature soldering processes due to moisture absorption, dimensional instability, and inadequate mechanical properties, especially under lead-free soldering conditions which require higher temperatures.
Innovation Solution
A reinforced flame retardant polymer composition comprising a semi-aromatic polyamide copolymer with specific molar ratios of dicarboxylic acids and diamines, combined with a reinforcing agent and flame retardant additives, providing improved blister resistance, dimensional stability, and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyamide compositions are used in E/E connectors, then the connectors can be manufactured with standard materials, but the connectors suffer from blistering during high-temperature soldering processes due to moisture absorption
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyamide by incorporating aromatic diamines (30-70 mol%) and controlling the ratio of aromatic to aliphatic diamines, which fundamentally changes the polymer's moisture absorption characteristics and thermal stability, thereby preventing blistering during soldering
Solution Approach 2:
The patent creates a composite polyamide system combining aromatic polyamide segments with aliphatic polyamide segments, where the aromatic segments provide dimensional stability and low moisture absorption, while the aliphatic segments maintain processability and mechanical properties
2Temperature
If the soldering temperature is increased for lead-free soldering, then the soldering process becomes effective, but the connectors experience increased blistering due to higher temperatures
Solution Approach 1:
The patent raises the glass transition temperature (Tg) of the polyamide to above 100°C through aromatic diamine incorporation, enabling the material to withstand lead-free soldering temperatures (200-250°C) without blistering, while maintaining adequate processability during injection molding
3Volume of moving object
If the connector cross-section is reduced for downsizing, then the connector size is reduced, but the dimensional stability under end-use conditions deteriorates
Solution Approach 1:
The patent increases the aromatic content (30-70 mol%) to enhance the polymer chain rigidity and intermolecular interactions, which significantly improves dimensional stability and heat deflection temperature, allowing thin-walled connectors to maintain shape stability at temperatures up to 100°C
4Stability of the object's composition
If the glass transition temperature is increased to improve high-temperature stability, then the dimensional stability improves, but the processability during injection molding deteriorates
Solution Approach 1:
The patent balances aromatic and aliphatic diamine content to create a composite structure where aromatic segments (providing high Tg and stability) are interspersed with aliphatic segments (providing flexibility and processability), achieving Tg > 100°C while maintaining adequate melt flow for injection molding
Solution Approach 2:
The patent creates local aromatic-rich domains within the polyamide chains that provide high-temperature stability, while the overall chain structure retains aliphatic character for processability, achieving differentiated properties at different structural levels
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 solution offers superior blister resistance, dimensional stability, and mechanical performance at high temperatures, outperforming conventional polyamide compositions like PA46 and PA9T, while maintaining good processability and electrical properties.
Implementation Method 1
Polymer compositions used in injection moulded parts for electrical and electronic applications have to comply with many requirements, generally including flame retardancy as a basic requirement... control of moisture absorption in the molded parts... Blistering occurs upon super-saturation of the housing resin with water vapor
Implementation Method 2
A reinforced flame retardant polymer composition comprising a semi-aromatic polyamide copolymer with specific molar ratios of dicarboxylic acids and diamines, combined with a reinforcing agent and flame retardant additives, providing improved blister resistance, dimensional stability, and mechanical properties
Implementation Method 3
Polymer compositions used in injection moulded parts for electrical and electronic applications have to comply with many requirements, generally including flame retardancy as a basic requirement... the presence of a flame retardant is essential to passing UL-94 V-0 flammability rating
Implementation Method 4
dimensional stability thereof under end-use conditions becomes a critical attribute of performance... component integrity and retention of pin position requires excellent dimensional stability under the high temperatures encountered during the soldering process
Data Source
AI summary
This invention relates to a flame retardant polyamide composition comprising a semi-aromatic polyamide, a flame retardant system and a reinforcing agent, wherein the semi-aromatic polyamide comprises units derived from dicarboxylic acids comprising terephthalic acid and aliphatic dicarboxylic acids, and aliphatic diamines. In the semi-aromatic polyamide the aliphatic diamines consist of 10-70 mole % of a short chain aliphatic diamine with 2-5 C atoms and 30-90 mole % of a long chain aliphatic diamine with at least 6 C atoms; the dicarboxylic acids consist of 5-65 mole % aliphatic dicarboxylic acid and optionally aromatic dicarboxylic acid other than terephthalic acid and 35-95 mole % terephthalic acid; and the combined molar amount of terephthalic acid and the long chain aliphatic diamine is at least 60 mole %, relative to the total molar amount of the dicarboxylic acids and diamines. The invention also relates to a housing for an electrical/electronic (E/E) connector and use therein of the flame retardant polyamide composition, to a surface mounting process wherein the E/E connector is used and to a surface mounted device comprising the E/E connector.