Solder Paste Transfer Process for Non-Planar Surfaces
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Solution Overview
Problem
Conventional solder paste transfer processes are inefficient and prone to defects when applied to non-planar surfaces, as they require manual dispensing and lack precision, increasing assembly costs and time.
Innovation Solution
A solder paste transfer process involving a transfer tool with a non-wettable surface, where solder paste is applied in a predefined configuration, inverted over the non-planar surface, and reflowed to flow accurately to solder pad locations, using a laser-cut stencil to control solder volumes and prevent bridging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manual dispensing is used for non-planar surfaces, then solder paste can be applied, but the process is time consuming and has high potential for solder defects
Solution Approach 1:
A transfer tool is introduced as an intermediary carrier between the solder paste source and the non-planar PCB surface. The transfer tool receives solder paste in a predefined configuration, is inverted over the PCB, and allows solder paste to flow onto the solder pads through controlled reflow, eliminating the need for direct manual dispensing while maintaining precision
Solution Approach 2:
The manual dispensing mechanical system is replaced with a thermal reflow system. Instead of using mechanical dispensing valves and positioning systems, the invention uses controlled heating to induce solder paste flow from the transfer tool to the PCB pads, simplifying the mechanical complexity while improving precision
2Ease of manufacture
If manual dispensing is used for non-planar surfaces, then solder paste can be applied, but there is high potential for causing solder defects
Solution Approach 1:
The transfer tool serves as a precision intermediary that pre-configures solder paste volumes and positions before transfer. This intermediary step ensures controlled solder paste flow and precise placement on non-planar surfaces, eliminating the variability and defect-prone nature of direct manual dispensing
Solution Approach 2:
The invention changes the thermal parameter (temperature) to control solder paste flow behavior. By applying controlled heat to induce reflow, the solder paste naturally flows to the correct locations with precise volume control, eliminating defects caused by manual dispensing variability
3Productivity
If automated screen print process is used, then solder paste application is efficient, but it cannot be used when circuit card is not flat
Solution Approach 1:
Instead of bringing the PCB up to the solder paste application point, the transfer tool with solder paste is inverted and brought down to the PCB surface. This inversion allows the solder paste to flow downward onto the non-planar surface under gravity and capillary action, adapting the automated process to non-flat geometries
Solution Approach 2:
The invention utilizes the phase transition of solder paste from solid-like to liquid-like state through controlled heating. This phase change enables the solder paste to flow from the transfer tool to the PCB pads, allowing automated application to work on non-planar surfaces where traditional screen printing cannot reach
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
Ensures precise and controlled solder application to non-planar surfaces, reducing defects and assembly costs by allowing for accurate wetting and proper solder joint formation.
Implementation Method 1
reflowing the solder paste to flow from the transfer tool to the solder pad locations
Implementation Method 2
reflowing the solder paste to flow from the transfer tool to the solder pad locations
Implementation Method 3
transfer tool formed of a material that is non-wettable with respect to the solder paste
Data Source
AI summary
A solder paste transfer process is provided and includes defining an arrangement of solder pad locations on a surface, applying solder paste onto a transfer tool in a pre-defined configuration reflective of the arrangement, disposing the transfer tool in an inverted orientation proximate to the surface and reflowing the solder paste to flow from the transfer tool to the solder pad locations.