Transfer Pin Tip Geometry for Consistent Solder Paste Release
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Solution Overview
Problem
Solder balls in solder paste are prone to crushing during dipping and transferring, leading to inconsistent transfer shapes and frequent cleaning needs, which complicates continuous transfer processes and requires precise height control of the transfer pin.
Innovation Solution
A transfer pin with a releasing portion, such as a tapered or hump-shaped tip end, is used to minimize solder ball crushing by allowing easy release of solder paste, and a transfer device that selects or sets the taper angle and film thickness based on transfer diameter to optimize solder paste transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the transfer pin uses a conventional tip shape (flat, hemisphere, or crest-shaped), then the solder paste can be transferred to the mounting portion, but the solder ball may be crushed during dipping and transferring, causing the solder paste to be deposited on the transfer pin
Solution Approach 1:
The tip end portion of the transfer pin is formed with a spherical surface having a specific radius of curvature. This curved surface allows the solder paste to be transferred without crushing the solder ball, as the spherical geometry distributes the contact pressure more evenly compared to flat or sharp tip shapes.
Solution Approach 2:
The invention specifies particular parameters for the spherical surface (radius of curvature between 0.01 mm to 0.05 mm) and the main body portion (diameter between 0.1 mm to 0.5 mm, length between 0.5 mm to 2.0 mm). By optimizing these geometric parameters, the transfer pin achieves both effective solder paste transfer and prevention of solder ball crushing.
2Object-generated harmful factors
If the position control (height control) accuracy is improved to suppress solder ball crushing, then the solder ball crushing can be reduced, but the position control system becomes advanced and complicated
Solution Approach 1:
The invention replaces the need for complex mechanical position control systems with a geometric solution. By designing the tip end portion with a specific spherical surface geometry, the system achieves consistent solder paste transfer without requiring high-precision height control mechanisms, thereby simplifying the overall system.
3Manufacturing precision
If the transfer pin is cleaned frequently to maintain transfer shape consistency, then the transfer shape can be maintained, but continuous transfer for a long time becomes difficult
Solution Approach 1:
The spherical surface at the tip end portion is designed to prevent solder paste deposition during the transfer process. This geometric feature inherently reduces solder accumulation that would otherwise require frequent cleaning, thereby enabling continuous transfer operations for extended periods while maintaining consistent transfer shape.
Data Source
AI summary
A transfer pin includes a main body portion, and a releasing portion formed on a tip end side of the main body portion, and configured to, when a solder paste including a solder ball is dipped and transferred to a mounting portion of a component of a board, release the solder paste from a tip end portion of the main body portion.