Technical Library: solder ball contamination on stencils (Page 1 of 1)

Study on Solder Joint Reliability of Fine Pitch CSP

Technical Library | 2015-12-31 15:19:28.0

Today's consumer electronic product are characterized by miniatuization, portability and light weight with high performance, especially for 3G mobile products. In the future more fine pitch CSPs (0.4mm) component will be required. However, the product reliability has been a big challenge with the fine pitch CSP. Firstly, the fine pitch CSPs are with smaller solder balls of 0.25mm diameter or even smaller. The small solder ball and pad size do weaken the solder connection and the adhesion of the pad and substrate, thus the pad will peel off easily from the PCB substrate. In addition, miniature solder joint reduce the strength during mechanical vibration, thermal shock, fatigue failure, etc. Secondly, applying sufficient solder paste evenly on the small pad of the CSP is difficult because stencil opening is only 0.25mm or less. This issue can be solved using the high end type of stencil such as Electroforming which will increase the cost.

Flex (Flextronics International)

NanoClear Coated Stencils

Technical Library | 2023-05-22 16:49:42.0

Our customers' issues • Apertures are getting smaller • Paste does not release as well • Contaminates the bottom of the stencil • Increases defects / reduces yield  Insufficient solder  Bridging  Solder balls on surface of PCB  Flux residue • Requires more frequent cleaning • Reduced efficiency (wasted time) • Increased use of consumables (cost)  USC fabric (use "cheap" fabric to reduce cost)  Lint creates more defects  Cleaning chemistries (use IPA to reduce cost)  IPA breaks down flux and can create more defects

ASM Assembly Systems (DEK)

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Count On Tools, Inc.
Count On Tools, Inc.

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Manufacturer

2481 Hilton Drive
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Phone: (770) 538-0411