Wrap-around Overmold for Electronic Assembly Delamination
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Solution Overview
Problem
Conventional electronic assemblies experience delamination issues at the interface between the backplate and overmolding material due to thermal cycling, attributed to differences in the coefficient of thermal expansion between the backplate and overmold material.
Innovation Solution
The overmold body is configured to wrap around the sides and partially around the backside of the backplate, ensuring adhesive contact along both sides and part of the backside, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonding is used between backplate and overmolding material, then mechanical resistance to shock and vibration is improved, but delamination occurs during thermal cycling due to coefficient of thermal expansion difference
Solution Approach 1:
The overmold body is configured to wrap around the backplate in a three-dimensional manner, extending over the front surface and around the sides. This dimensional extension transforms the bonding interface from a simple planar contact to a multi-surface configuration, increasing the effective bonding area and distributing thermal stress across multiple surfaces, thereby preventing delamination during thermal cycling while maintaining mechanical strength
2Reliability
If overmold body wraps around sides and backside of backplate, then delamination is prevented, but manufacturing complexity increases
Solution Approach 1:
The overmold body is designed as an integrated, monolithic structure that combines multiple protective functions into a single component. By merging the sealing function, the structural support function, and the delamination prevention function into one wrap-around overmold body, the design achieves reliability without proportionally increasing complexity, as the unified structure is manufactured as a single piece rather than multiple assembled components
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 prevents delamination, enhances corrosion resistance, and secures the printed circuit board assembly and electrical connector within the electronic assembly.
Implementation Method 1
an adhesive bond between the backplate and the overmolding material
Implementation Method 2
a substantial difference between the coefficient of thermal expansion of the backplate and the overmold material
Data Source
Figure 1~3
AI summary
An improved overmolded electronic assembly includes a backplate provided with a recessed edge, a circuit substrate on the backplate, at least one electronic component mounted on the circuit substrate, conductive traces on the circuit substrate which together with the electronic component(s) defines a circuit device, an electrical connector, and an overmold body that has peripheral edges that wrap around sides of the backplate and onto the edge recesses. The resulting over wrap feature eliminates delamination problems that would otherwise occur during thermal cycling of the electronic assembly, improves corrosion resistance at connector-to-backplate interfaces, and enhances securement of the printed circuit board assembly and electrical connector to the assembly.