PCB Rework via Solder Paste Gravity Draw
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Solution Overview
Problem
Intrusive soldering methods face challenges with insufficient solder volume in plated through-hole components, leading to unreliable connections and the need for labor-intensive rework processes that can damage components, especially when dealing with mixed surface-mount and through-hole components on printed circuit boards.
Innovation Solution
A method involving the application of solder paste to plated through holes on one side of a printed circuit board, using gravitational force and/or vacuum to draw the solder into contact with pins, allowing for reworked solder bonds without removing or replacing the component, thus addressing the issue of insufficient solder and improving connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wave soldering or intrusive soldering methods are used, then through-hole components can be soldered to the board, but insufficient solder volume leads to unreliable connections and requires labor-intensive rework that can damage components
Solution Approach 1:
Solder paste is applied to the plated through-holes before component placement and soldering. This preliminary application ensures sufficient solder volume is available in the holes, preventing insufficient solder defects and eliminating the need for complex rework procedures later.
Solution Approach 2:
The patent replaces traditional wave soldering mechanical systems with a solder paste application system combined with reflow or selective soldering. This substitution provides better solder volume control and reduces the need for labor-intensive rework, improving both reliability and ease of repair.
2Productivity
If intrusive soldering is used to eliminate wave soldering, then assembly process steps are reduced, but solder paste application and control complexity increases
Solution Approach 1:
Solder paste is applied in advance to the plated through-holes using stencil printing or dispensing systems before component placement. This preliminary action consolidates the soldering process, eliminating the need for separate wave soldering equipment and reducing overall assembly complexity while maintaining productivity.
Solution Approach 2:
The solder paste application system serves multiple functions: it provides solder material, acts as a flux, and enables both through-hole and surface-mount component attachment in a single process flow. This multi-functionality reduces the need for separate specialized equipment, lowering system complexity while maintaining high productivity.
3Reliability
If solder paste is applied to plated through holes, then sufficient solder volume is achieved, but additional process steps are required
Solution Approach 1:
The solder paste application step is merged with the existing reflow or selective soldering process. The same heating system that reflows solder for surface-mount components also melts the solder paste in the plated through-holes. This merging consolidates multiple process steps into one, improving reliability without significantly increasing process complexity.
Solution Approach 2:
The reflow or selective soldering system performs dual functions: it attaches surface-mount components and simultaneously melts the solder paste in plated through-holes to create reliable joints. This multi-functionality achieves high solder joint quality without adding separate dedicated equipment or process steps.
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 approach enables reliable solder bonding without component removal, reducing damage and labor, and enhances the efficiency of the rework process by using gravitational force and vacuum to ensure proper solder distribution within the plated through holes.
Implementation Method 1
drawing the solder paste using gravitational force to the pins
Implementation Method 2
drawing the solder paste with a vacuum to the pins
Implementation Method 3
melting the solder paste
Data Source
AI summary
A method for forming an electronic device that includes solder bonding pins from a component to plated through holes of a board, the component being positioned on a first side of the board; and applying solder paste to openings of the plated through holes on a second side of the board opposite the first side of the board that the component is positioned on. The method can further include drawing the solder paste to the pins to provide a reworked solder bond bonding at least one of the pins to the plated through hole.