Offset Solder Terminal Structure for Side-Facing Die Wetting
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Solution Overview
Problem
Systems with perpendicular or side-facing die terminals on printed circuit boards often experience imperfect solder wetting due to the volume and placement of solder balls and under bump metallization (UBM) pads, leading to marginal or total non-wets, and increasing solder volume can result in undesired short circuits.
Innovation Solution
The design includes a semiconductor die with conductive terminals having a foot and pillar portion, where the solder structure extends on the conductive terminal and is offset towards the die's second side, allowing for proper wetting without increasing solder volume, thereby avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder volume is increased to improve wetting capability, then wetting capability is improved, but risk of short circuits increases
Solution Approach 1:
The conductive terminal employs different geometries at different locations: a wider foot portion at the base for solder attachment and a narrower pillar portion extending upward. This local variation in cross-sectional area allows the solder to concentrate wetting at the foot portion while the narrower pillar prevents excessive solder overflow that could cause short circuits.
Solution Approach 2:
The conductive terminal extends in the vertical dimension with a pillar portion that rises from the foot portion. This vertical extension provides a controlled pathway for solder flow, allowing the solder to wet the terminal surface area progressively from bottom to top, improving wetting capability while containing the solder within defined boundaries.
2Reliability
If solder volume is increased to improve marginality of perpendicular terminal wetting, then wetting reliability is improved, but chance of undesired short circuits increases
Solution Approach 1:
The conductive terminal employs different geometries at different locations: a wider foot portion at the base for solder attachment and a narrower pillar portion extending upward. This local variation in cross-sectional area allows the solder to concentrate wetting at the foot portion while the narrower pillar prevents excessive solder overflow that could cause short circuits.
Solution Approach 2:
The conductive terminal extends in the vertical dimension with a pillar portion that rises from the foot portion. This vertical extension provides a controlled pathway for solder flow, allowing the solder to wet the terminal surface area progressively from bottom to top, improving wetting capability while containing the solder within defined boundaries.
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 ensures robust and reliable solder connections to the circuit board, preventing short circuits and improving wetting capability without the need for larger solder balls, even with tighter UBM pad configurations.
Implementation Method 1
performing an electroplating process to form a conductive terminal in the opening with a foot portion and a pillar portion
Data Source
AI summary
An electronic device includes a semiconductor die having a first side, an orthogonal second side for mounting to a substrate or circuit board, a conductive terminal on the first side, the conductive terminal having a center that is spaced apart from the second side by a first distance along a direction, and a solder structure extending on the conductive terminal, the solder structure having a center that is spaced apart from the center of the conductive terminal by a non-zero second distance along the direction.