Grooved Recessed Connection Pad for Reliable Flux Coverage
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Solution Overview
Problem
Existing semiconductor package manufacturing processes face challenges in ensuring reliable electrical connections due to issues with flux distribution and oxide removal on connection pads, particularly when the flux is applied at a deviated position.
Innovation Solution
The semiconductor package incorporates a connection pad with a recessed portion and a groove pattern on its inner sidewall, which allows the flux to flow along a spiral path and cover the entire surface, even if applied off-center, ensuring thorough oxide removal and improved solder connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flux is applied on a flat connection pad surface, then the application process is simple, but the flux distribution is uneven and oxide removal is incomplete when applied at deviated position
Solution Approach 1:
The connection pad surface is transformed from a flat plane to a curved surface with a recessed portion and inclined inner sidewall. This curvature guides the flux to flow downward along the inclined surface, ensuring complete coverage of the connection pad surface including the tip portion, thereby achieving reliable oxide removal and bonding even when flux is applied at a deviated position
Solution Approach 2:
The invention adds a vertical dimension to the flux flow path by creating a recessed portion with an inclined inner sidewall. Instead of flux spreading horizontally on a flat surface, it now flows downward along the inclined surface, creating a three-dimensional flow path that ensures comprehensive coverage and reliable oxide removal
2Device complexity
If the connection pad has a simple flat structure, then the manufacturing process is easier, but the flux cannot flow uniformly to cover the entire surface
Solution Approach 1:
The connection pad is designed with a recessed portion and an inclined inner sidewall that curves downward. This curvature naturally guides the flux to flow uniformly across the entire surface including the tip, achieving precise flux distribution without requiring complex external control mechanisms
Solution Approach 2:
The connection pad surface is divided into different regions with different slopes: the outer sidewall is substantially vertical while the inner sidewall is inclined. This local variation in surface quality directs the flux flow path to ensure complete coverage of the tip portion while maintaining manufacturing feasibility
3Device complexity
If the inner sidewall is vertical, then the structure is simpler, but the flux does not flow along the sidewall to remove oxide from the tip portion
Solution Approach 1:
The inner sidewall is designed with an inclined surface that slopes downward from the top surface toward the bottom of the recessed portion. This inclination creates a gravitational and surface tension-driven flow path for the flux, enabling it to coat the tip portion of the connection pad and achieve complete oxide removal
Solution Approach 2:
The inclined inner sidewall structure enables the flux to self-flow along the surface without requiring external application forces. The geometry itself guides the flux to naturally cover the tip portion, making the oxide removal process self-directed and reliable
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 enhances the bonding reliability between the connection pad and the solder connection structure by ensuring complete oxide removal and uniform flux distribution, even with positional errors in flux application.
Implementation Method 1
a groove pattern formed on the inner sidewall... allows the flux to flow along a spiral path and cover the entire surface
Data Source
AI summary
A semiconductor package includes a package substrate, a connection pad including a recessed portion disposed on one surface of the package substrate, and an insulating pattern disposed on the one surface of the package substrate to be spaced apart from the connection pad. The connection pad includes an outer sidewall, an inner sidewall in the recessed portion inclining in an inward direction from an upper portion, and a groove pattern formed on the inner sidewall.