Semiconductor Package Surface Layout to Keep ID Marks Visible
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Solution Overview
Problem
The visibility of identification marks on semiconductor packages is compromised due to flux oozing from terminals during solder mounting, especially as the number of terminals increases and package miniaturization occurs, causing the mark to become less visible.
Innovation Solution
A smooth or convex/concave portion is introduced on the surface of the package between the terminals and the mark portion, which is smoother than the surrounding area, to prevent flux from spreading onto the mark, thereby maintaining visibility and allowing for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of terminals is increased or package miniaturization is performed, then the terminal density is improved, but the distance between terminals and the mark decreases causing flux to ooze onto the mark during solder mounting
Solution Approach 1:
A smooth portion is introduced as an intermediary region between the terminal and the mark portion. This smooth portion acts as a barrier that prevents flux from the terminal from reaching and contaminating the mark portion, while still allowing the package to maintain high terminal density and miniaturization.
Solution Approach 2:
The surface of the base plate is given different qualities in different regions: the smooth portion has a specifically controlled smoothness (Ra value) that differs from other portions. This local differentiation in surface quality allows flux to be contained in specific regions while maintaining overall package miniaturization and high terminal density.
2Volume of moving object
If the distance between terminals and the mark is reduced for miniaturization, then the package size is reduced, but the mark visibility decreases due to flux contamination
Solution Approach 1:
The smooth portion serves as a protective intermediary zone that physically separates the terminal region from the mark portion. This allows the package to be miniaturized with reduced distances between terminals and marks while the smooth portion prevents flux from contaminating the mark, thereby maintaining mark visibility.
Solution Approach 2:
By creating a localized smooth region with controlled surface properties between the terminal and mark, the invention enables package miniaturization without sacrificing mark visibility. The local quality modification (smoothness) in this specific region prevents flux spread while allowing overall package size reduction.
3Object-affected harmful factors
If a smooth portion is provided between terminals and mark, then flux oozing is suppressed and mark visibility is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The invention controls the surface roughness parameter (Ra value) of the base plate in the smooth portion to be within a specific range (0.1 μm to 3 μm). By defining a quantitative parameter range for surface smoothness, the invention prevents flux oozing while keeping the manufacturing process manageable through parameter specification rather than complex structural design.
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 smooth or protruding/concave portion effectively suppresses flux oozing, ensuring the visibility of the identification mark and enabling package miniaturization by maintaining a clear distance between terminals and marks.
Implementation Method 1
A smooth portion, which is smoother than another portion between the plurality of terminals and the mark portion, is provided on the one surface and between at least one terminal among the plurality of terminals and the mark portion
Data Source
AI summary
A package includes a plurality of terminals, a mark portion, and a base plate. a mark for identification is provided on the mark portion. The plurality of terminals and the mark portion are provided on one surface of the base plate. A smooth portion, which is smoother than another portion between the plurality of terminals and the mark portion, is provided on the one surface and between at least one terminal among the plurality of terminals and the mark portion.