Conductive Post Bump Structure to Minimize Solder Side Wicking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor packages often suffer from shape abnormalities in solder balls, leading to yield loss and poor electrical characteristics due to defects such as side wicking, bridge formation, and thermal expansion differences.
Innovation Solution
A semiconductor package design featuring a conductive post structure with an insulating pattern on its side surfaces and a solder bump that contacts only the upper surface of the conductive post, minimizing side wicking and bridge defects during reflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional conductive post structure is used without insulating patterns, then the manufacturing process is simpler, but side wicking and bridge defects occur during reflow, leading to shape abnormalities in solder balls
Solution Approach 1:
The conductive post structure is segmented by dividing it into an upper portion and a lower portion with different properties. The lower portion has an insulating pattern to prevent side wicking, while the upper portion remains exposed for proper solder ball formation. This segmentation allows each portion to serve its specific function without interfering with the other.
Solution Approach 2:
Different portions of the conductive post structure are given different local qualities: the lower portion is covered with an insulating pattern to prevent harmful solder flow, while the upper portion is left exposed to allow proper solder ball formation. This local differentiation of properties solves the contradiction by applying insulation only where needed rather than uniformly across the entire structure.
2Reliability
If the insulating pattern covers the entire conductive post structure, then side wicking is prevented, but solder ball formation and electrical connectivity are compromised
Solution Approach 1:
The insulating pattern is segmented to cover only the lower portion of the conductive post structure, leaving the upper portion exposed. This segmentation allows the insulating pattern to prevent side wicking in the lower region while maintaining proper solder ball formation and electrical connectivity in the upper region.
Solution Approach 2:
The insulating pattern is applied locally to the lower portion of the conductive post structure where side wicking occurs, rather than covering the entire structure. This local application prevents harmful solder flow while preserving the upper portion for proper electrical connectivity and solder ball formation.
3Productivity
If solder balls are formed with conventional methods, then the process is faster, but thermal expansion differences cause defects and yield loss
Solution Approach 1:
The insulating pattern is applied beforehand to the lower portion of the conductive post structure to prevent side wicking and bridge defects during reflow. This preventive measure cushions against potential defects caused by thermal expansion differences, ensuring proper solder ball formation and reducing yield loss without requiring additional time for defect correction.
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 design reduces defects and enhances structural stability and electrical connectivity by preventing excessive solder flow and ensuring strong connections, thereby improving manufacturing yield and performance.
Implementation Method 1
the insulating pattern is spaced apart from the solder bump... preventing excessive solder flow
Implementation Method 2
a solder bump connected to an upper surface of the conductive post structure... ensuring strong connections
Data Source
AI summary
A semiconductor package may include a substrate, a first pad on the substrate, and a first bump structure on the first pad, wherein the first bump structure includes a first conductive post structure on the first pad and connected to an upper surface of the first pad and a first solder bump connected to an upper surface of the first conductive post structure, and the first conductive post structure includes a first conductive portion and a first insulating pattern on a side surface of a lower portion of the first conductive portion, wherein a side surface of an upper portion of the first conductive portion is free of the first insulating pattern.