Dual-Side Mold Module Metal Posts for Reflow-Stable Mounting
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Solution Overview
Problem
Solder balls in packaged electronic modules can liquify during high-temperature reflow processes, leading to shape changes and position restrictions during mounting, while conductive copper posts are prone to oxidation and costly electrolytic plating.
Innovation Solution
Implement conductive features like metal posts with high melting temperatures and apply a solderable material layer that covers the surface to prevent oxidation and ensure secure electrical connections during mounting, with configurations allowing the surface to be coplanar or recessed relative to the overmold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solder balls are used for electrical connections, then cost is reduced and ease of manufacture is improved, but the solder balls liquify during high-temperature reflow processes causing shape changes and position restrictions
Solution Approach 1:
The patent changes the material parameter of the conductive feature from low-melting-point solder to high-melting-point metal (such as copper with melting point above 1000°C), enabling the conductive feature to withstand reflow soldering temperatures without liquifying, thus maintaining shape and position stability during mounting operations
Solution Approach 2:
The patent employs a composite structure consisting of a high-melting-point metal core (copper post) combined with a solderable coating layer, creating a material composite that simultaneously provides high-temperature stability and solderability, resolving the contradiction between thermal stability and ease of joining
2Reliability
If conductive copper posts are used for electrical connections, then reliability is improved and shape stability is maintained during mounting, but oxidation occurs and costly electrolytic plating is required
Solution Approach 1:
The patent uses a composite material structure with a copper core providing high-melting-point stability and a solderable coating layer (such as tin, nickel, or silver) providing oxidation resistance and solderability, eliminating the need for complex electrolytic plating processes while maintaining reliability
Solution Approach 2:
The solderable coating layer acts as a protective barrier creating an inert environment for the copper core, preventing oxidation during storage and mounting operations, thereby maintaining reliability without requiring additional protective measures
3Manufacturing precision
If the conductive feature surface is coplanar with the mounting surface, then mounting precision is improved, but the conductive feature is exposed to oxidation
Solution Approach 1:
The patent applies a solderable coating layer over the high-melting-point metal core, creating a composite structure where the coating layer serves as a protective barrier against oxidation while the underlying metal core maintains electrical conductivity and structural integrity, allowing the surface to be coplanar without oxidation exposure
4Object-affected harmful factors
If the conductive feature surface is recessed from the mounting surface, then oxidation protection is improved, but mounting precision and electrical connection reliability deteriorate
Solution Approach 1:
The solderable coating layer extends to the surface (or slightly beyond) the recessed high-melting-point metal core, creating a composite structure where the coating provides both oxidation protection and a reliable soldering surface at the correct elevation, eliminating the trade-off between protection and precision
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 prevents shape changes and oxidation, ensuring reliable electrical connections and secure mounting without additional position restrictions, enhancing the reliability and cost-effectiveness of the packaging process.
Implementation Method 1
apply a solderable material layer that covers the surface to prevent oxidation
Implementation Method 2
conductive material having a sufficiently high melting temperature so that the conductive features do not melt during a mounting operation
Data Source
AI summary
A packaged module can include a packaging substrate with first and sides, first and second components mounted on the first and second sides, respectively, and first and second overmolds implemented on the first and second sides, respectively, with the second overmold defining a mounting surface. The packaged module can further include a plurality of conductive features implemented on the second side of the packaging substrate to provide electrical connections for the packaged module, with the conductive features being formed from conductive material having a sufficiently high melting temperature so that the conductive features do not melt during a mounting operation. Each conductive feature can have a surface that is substantially coplanar with or recessed with respect to the mounting surface, and a solderable material layer can be dimensioned to cover the surface of each conductive feature.