Screen Printing Apparatus for Circuit Board Recesses
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Solution Overview
Problem
Screen printing on cavity circuit boards with three-dimensional masks faces challenges in achieving efficient and high-quality printing due to differences in filling paste into pattern holes on planar and fitting portions, and inadequate mask cleaning due to non-planar surfaces.
Innovation Solution
A screen printing apparatus with upstream and downstream portions that use distinct masks and squeegee mechanisms to sequentially print paste on upper-surface and bottom-surface areas of circuit boards, ensuring proper paste filling and independent mask cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a three-dimensional screen mask is used to print paste on both upper surface and recess bottom surfaces simultaneously, then printing efficiency is improved, but printing quality deteriorates due to different filling conditions in planar and fitting portions
Solution Approach 1:
The patent divides the screen printing process into two separate printing portions: an upstream screen printing portion for printing paste on the bottom surfaces of recesses, and a downstream screen printing portion for printing paste on the upper surface. This segmentation allows each portion to be optimized independently, with the upstream portion using a three-dimensional screen mask with fitting portions that extend into recesses, and the downstream portion using a planar screen mask, thereby achieving both high printing efficiency and excellent printing quality
Solution Approach 2:
The patent applies different screen mask structures to different printing locations: the upstream screen printing portion uses a three-dimensional screen mask with fitting portions having specific depth and opening dimensions optimized for recess bottom surface printing, while the downstream screen printing portion uses a planar screen mask optimized for upper surface printing. This local quality approach ensures optimal printing conditions for each specific printing location
2Adaptability or versatility
If a three-dimensional screen mask is used, then paste can be printed on recess bottom surfaces, but mask cleaning becomes inadequate due to non-planar surfaces
Solution Approach 1:
The patent separates the screen masks into two distinct portions: a three-dimensional screen mask for the upstream screen printing portion that can print on recess bottom surfaces, and a planar screen mask for the downstream screen printing portion. The planar screen mask in the downstream portion can be effectively cleaned by conventional mask cleaning mechanisms, while the three-dimensional screen mask is dedicated to recess printing, thus resolving the cleaning effectiveness issue
Solution Approach 2:
The patent extracts the planar screen mask function from the three-dimensional screen mask by implementing a separate downstream screen printing portion with its own planar screen mask. This allows the planar screen mask to be used where effective cleaning is required, while the three-dimensional screen mask is used exclusively for recess printing where its complex structure is necessary
Data Source
AI summary
The present invention provides a screen printing apparatus and screen printing method which, in screen printing that is to be performed on the upper surface of a circuit board, and the bottom surfaces of recess openings in the upper surface, can efficiently perform a printing work while ensuring an excellent printing quality. In a screen printing apparatus which prints a paste for bonding an electronic component on an upper surface and a bottom-surface of a recess, a printing apparatus 2(1) and a printing apparatus 2(2) which sequentially 10 print the paste in two steps on the circuit board are placed in series. The printing apparatus 2(1) on the upstream side includes a bottom-surface printing mask which is provided in correspondence with the bottom surface of the recess, and a closed squeegee mechanism 36A which butts against and slides over an upper surface of the bottom-surface printing mask to 15 pressurize and supply the paste. The printing apparatus 2(2) on the downstream side includes an upper-surface printing mask which is provided in correspondence with the upper surface and an opened squeegee mechanism 36B which butts against and slides over an upper surface of the upper-surface printing mask to fill the paste into pattern holes.