Multi-Stencil Solder Paste Printing for PCB Precision
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Solution Overview
Problem
Current solder printing techniques for PCBs are inefficient due to the complexity and high cost of stencils, requiring excessive time and often resulting in imprecise solder patterns and inadequate filling of through holes, which increases manufacturing costs and reduces speed.
Innovation Solution
The use of multiple stencils, with one being substantially planar and having through-hole apertures to fill through holes and another with surface-mounted component apertures to print solder pads, allowing for improved precision and reduced smearing by controlling the flow and deposition of solder paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single stencil is used to print both through-hole fills and surface-mount pads, then device complexity is reduced, but manufacturing precision deteriorates due to the conflicting requirements of deep hole filling versus shallow pad printing
Solution Approach 1:
The patent divides the single stencil function into two separate stencils: a first stencil optimized for through-hole filling with apertures sized and shaped for deep hole deposition, and a second stencil optimized for surface-mount pad printing with apertures sized for shallow pad deposition. This segmentation allows each stencil to be independently optimized for its specific function, resolving the precision conflict while managing overall system complexity.
Solution Approach 2:
The patent introduces a sequential temporal dimension to the printing process, performing through-hole filling first, then surface-mount pad printing second. This dimensional separation in time allows each stencil to operate under its optimal conditions without interference, achieving high precision for both operations despite using multiple stencils.
2Productivity
If a single stencil is used for both through-hole filling and surface-mount printing, then the number of steps is reduced, but productivity deteriorates due to the time required to fill deep through holes
Solution Approach 1:
By segmenting the printing process into two separate operations with two specialized stencils, the patent enables parallel optimization of each step. The first stencil可以快速填充通孔，而第二 stencil 可以快速印刷表面贴装焊盘，整体生产效率得到提升，因为每个 stencil 都针对其特定功能进行了优化，减少了调整和优化时间。
Solution Approach 2:
The patent performs through-hole filling as a preliminary action before surface-mount pad printing. This sequencing allows the solder paste to be deposited into the deep through holes first, establishing a foundation that prevents solder bridging during the subsequent pad printing operation, thereby enabling faster overall production with higher quality results.
3Reliability
If excessive solder paste is used to fill through holes, then filling completeness is improved, but harmful factors increase due to solder smearing on the board surface
Solution Approach 1:
The patent segments the solder deposition process into two distinct phases: first, through-hole filling with controlled paste volume through specifically designed aperture geometries; second, surface-mount pad printing with separate paste application. This segmentation ensures that each phase uses the appropriate amount of solder paste for its specific purpose, preventing excess paste from smearing on the board surface while ensuring adequate through-hole filling.
Solution Approach 2:
The patent applies local quality by designing the first stencil with apertures that control paste flow specifically for deep hole filling, creating a localized deposition pattern that fills holes without excessive surface paste. The second stencil then applies paste locally to surface-mount pads with precise control, ensuring each area receives the appropriate amount of solder paste for its specific function, thereby eliminating smearing while maintaining filling adequacy.
Data Source
AI summary
A method of printing solder paste in a component board and a stencil set for doing the same are disclosed. In one embodiment, the method includes using a first stencil having a first thickness to print solder paste into at least one through hole in the component board. The method further includes using a second stencil having a second thickness to print solder paste for at least one surface mounted part on the component board, subsequent to using the first stencil.