Bonding Plastic Component to PCB Using Low-Melting Alloy
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Solution Overview
Problem
Conventional methods for bonding plastic components to printed circuit boards in optical systems face issues with precise positioning, incomplete curing of adhesives, and environmental sensitivity, leading to functional degradation and reduced reliability.
Innovation Solution
A method involving a metal positioning member with a welding layer made of a metal alloy with a low melting point, which is melted and solidified to secure the plastic component to the printed circuit board, ensuring precise positioning and stability while avoiding the limitations of UV glue and thermal curing adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV glue is used for bonding the plastic component to the printed circuit board, then the bonding process can be completed at room temperature, but the UV light is blocked by the plastic component and printed circuit board causing incomplete curing of the UV glue
Solution Approach 1:
The patent changes the bonding mechanism from UV-curing (light-based) to thermal-curing (heat-based) by using a hot plate. This parameter change in the curing method eliminates the UV light blocking issue while achieving complete curing of the bonding agent, resolving the contradiction between curing completeness and UV light blocking.
2Reliability
If thermal curing adhesive is used to avoid UV light blocking, then complete curing can be achieved, but the density variation during curing causes significant volume variation and position changes
Solution Approach 1:
The patent uses a low-viscosity bonding agent that minimizes density variation during thermal curing. By changing the material parameter (viscosity) of the bonding agent, the volume variation during curing is reduced, thereby maintaining positioning precision while achieving complete curing.
Solution Approach 2:
The patent employs a composite bonding system consisting of a low-viscosity bonding agent combined with a releasing agent. This composite material approach reduces the harmful effects of thermal curing (volume expansion) while maintaining the benefits of complete curing, thus resolving the contradiction between curing completeness and positioning precision.
3Manufacturing precision
If the bonding agent volume is reduced to minimize position changes during curing, then positioning precision is maintained, but the bonding strength may be insufficient
Solution Approach 1:
The patent changes the viscosity parameter of the bonding agent to low viscosity, allowing a small volume of bonding agent to achieve sufficient bonding strength. The low viscosity enables the bonding agent to spread effectively and create strong adhesion even in minimal quantities, thus maintaining both positioning precision and bonding strength.
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 method enhances the precision and reliability of the bonding process by ensuring complete curing and minimizing volume changes, thus maintaining the intended positioning and performance of the optical components.
Implementation Method 1
melting the at least one welding layer using a heating device while the plastic component is maintained in the positioning position
Implementation Method 2
cooling the at least one welding layer while the plastic component is maintained in the positioning position so as to solidify the at least one welding layer
Implementation Method 3
disposing between the first bonding surface of the at least one metal base of the printed circuit board and the second bonding surface of the at least one positioning member, at least one welding layer made of a welding metal
Data Source
AI summary
A method for bonding aplastic component to a printed circuit board includes the steps of: a) providing the plastic component, the printed circuit board, and at least one positioning member, b) disposing at least one welding layer, c) positioning the plastic component and the printed circuit board relative to each other, d) melting the at least one welding layer while the plastic component is maintained in a positioning position, and e) cooling the at least one welding layer while the plastic component is maintained in the positioning position.