Flux Pin Wetting Control for Consistent Multi-Pad Dotting
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Solution Overview
Problem
Existing flux dotting tools struggle to maintain a consistent flux application on multiple pads during the miniaturization of electronic and semiconductor devices, leading to inadequate solder ball formation due to uneven flux distribution.
Innovation Solution
A flux dotting tool with flux pins featuring a flux blocking structure that limits the wetting region, preventing flux from climbing and ensuring a constant flux application, comprising a cylindrical flux holding portion with a tapered wetting portion and a protruding flux blocking structure, which maintains the flux within a predetermined area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flux pins without flux blocking structure are used, then flux can be easily applied to pads, but flux climbs beyond the intended area causing inconsistent dotting amount
Solution Approach 1:
The flux pin is segmented into distinct functional regions: a wetting portion for flux absorption, a non-wetting portion blocked by the flux blocking structure, and the flux blocking structure itself. This segmentation prevents flux from climbing beyond the wetting portion, ensuring consistent dotting amount while maintaining a relatively simple overall structure.
Solution Approach 2:
The flux pin exhibits local quality differentiation through the flux blocking structure, which creates a specific wetting region with controlled properties. The wetting portion has surface properties that allow flux adhesion, while the non-wetting portion has properties that prevent flux climbing, achieving precise flux placement without excessive complexity.
2Quantity of substance
If flux pins with large diameter are used, then flux holding capacity increases, but flux distribution uniformity across multiple pads decreases
Solution Approach 1:
By segmenting the flux pin into a wetting portion and a non-wetting portion separated by the flux blocking structure, the design allows the pin to hold sufficient flux in the wetting portion while preventing overflow. This ensures each pin delivers a consistent, appropriate amount of flux to its corresponding pad, maintaining uniformity across multiple pads.
Solution Approach 2:
The flux pin is designed to hold more flux than immediately needed (excessive action in terms of capacity), but the flux blocking structure limits the actual flux transfer to the precise amount required (partial action). This ensures sufficient flux availability while maintaining precise control over the dotting amount for uniform distribution.
3Manufacturing precision
If flux pins without elastic structure are used, then device simplicity is maintained, but flux dotting consistency during prolonged operation deteriorates
Solution Approach 1:
The elastic structure introduces dynamic capability to the flux pin assembly, allowing the pins to be pressed against the substrate and return to their original position. This dynamic action ensures consistent flux dotting during prolonged operation by maintaining proper contact pressure, while the elasticity allows for simple integration into the existing tool structure.
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 tool ensures a stable and consistent flux application, preventing flux from rising beyond the intended area, thereby maintaining a constant dotting amount even during prolonged processes, ensuring reliable solder ball formation and reducing defects in the reflow process.
Implementation Method 1
an elastic structure disposed on the plurality of flux pins in the internal space and configured to impart elastic force in the first direction
Implementation Method 2
the flux blocking structure is configured to limit a flux wetting region... a height of the wetting portion in the first direction has a ratio within a range of 1 to 3 with respect to a minimum diameter of a tip surface of the wetting portion in the second direction
Data Source
AI summary
A flux dotting tool is provided that includes: a housing having an internal space and a plurality of through-holes extending from the internal space to an outside of the housing; a plurality of flux pins disposed in the internal space to correspond to the plurality of through-holes, respectively, wherein each of the plurality of flux pins includes a flux holding portion extending in a first direction and that is exposed to the outside of the housing, and a flux blocking structure protruding in a second direction, perpendicular to the first direction, from a side surface of the flux holding portion, and the flux blocking structure is configured to limit a flux wetting region; and an elastic structure disposed on the plurality of flux pins in the internal space and configured to impart elastic force in the first direction.