Solder Bump Forming Member for Clean Fine-Pitch Electrode Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming solder bumps face challenges such as the formation of foreign substances due to the decomposition of sticky layers during heating, which can hinder the stable formation of solder bumps and lead to short circuit failures, especially when the gap between electrodes is narrow.
Innovation Solution
A solder bump forming member is developed, comprising a base substrate with recesses and solder particles within these recesses, where the solder particles have an average diameter of 1 to 35 μm and a C.V. value of 20% or less, and a part of the solder particle projects from the recess, ensuring proper contact and bonding with electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sticky layer is used to hold solder particles during transfer, then the solder particles can be positioned and transferred to electrodes, but the sticky layer decomposes during heating to form foreign substances that contaminate the solder and electrode interface
Solution Approach 1:
The invention removes the sticky layer entirely from the system. Instead of using a sticky layer to hold solder particles, the patent uses a mask with through-holes where solder particles are placed directly on the mask surface and transferred to electrodes through the holes, eliminating the source of foreign substance contamination while maintaining transfer capability
Solution Approach 2:
The mask serves as an intermediary structure that enables solder particle positioning and transfer without requiring a sticky layer. The mask with its through-holes provides the necessary positioning function, allowing solder particles to be held and transferred cleanly without decomposition products
2Manufacturing precision
If solder particles are transferred via pressure-sensitive adhesive, then solder balls can be positioned on electrodes, but the adhesive component remains on the solder ball surface causing bonding failures
Solution Approach 1:
The invention removes the pressure-sensitive adhesive from the transfer process. Solder particles are placed directly on the mask surface and transferred through mechanical contact and heating without any adhesive medium, eliminating contamination while maintaining positioning accuracy through the mask structure
Solution Approach 2:
The invention replaces the chemical bonding mechanism of pressure-sensitive adhesive with a physical transfer mechanism using the mask structure and controlled heating, eliminating adhesive residue while achieving precise positioning and reliable bonding
3Ease of manufacture
If solder balls are in contact with each other on the transfer sheet, then uniform arrangement is achieved, but solder bridges between adjacent electrodes cause short circuit failures
Solution Approach 1:
The mask is designed with discrete through-holes that are spatially separated, forcing solder particles to be positioned in isolated locations. This segmentation prevents solder particles from contacting each other during transfer, eliminating bridge formation while maintaining uniform arrangement through the structured hole pattern
Solution Approach 2:
The mask provides localized positioning at each through-hole location, ensuring solder particles are placed precisely where needed without affecting adjacent positions. This local control prevents unwanted solder contact between electrodes while achieving uniform distribution across the substrate
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 solution enables the manufacturing of connection structures with excellent insulation and conduction reliability, even when the number of connection points is small, by preventing foreign substance formation and ensuring stable solder bump formation without short circuits.
Implementation Method 1
heating is performed to a solder melting point or higher to melt and aggregate the solder
Implementation Method 2
the solder particle is exposed to a reducing atmosphere to remove an oxide film on the solder particle surface
Data Source
AI summary
A solder bump forming member including: a base substrate having a plurality of recesses; and solder particles in the recesses, in which the solder particle has an average particle diameter of 1 to 35 μm and a C.V. value of 20% or less, and a part of the solder particle projects from the recess, or in cross-sectional view, when a depth of the recess is designated as H1, and a height of the solder particle is designated as H2, H1<H2 is established.