Improving Solder Paste Printing


Reading time ( words)

In my recent conversation with process engineers at an EMS company here in the Philippines, they said one of the critical processes that determine yield in their line is the solder paste printing process. According to them, one of the key reasons for this is the incorrect printer set-up, which results in issues such as insufficient solder or solder bridging. Of the three elements involved in the process—stencil, solder paste, and printer—the stencil is considered one of the major factors affecting the transfer efficiency, accuracy, and consistency, of solder pastes into the pads, especially with the continuing trend towards miniaturization.

Indeed, in our latest survey on solder paste printing, a majority of the respondents highlighted stencils as one of their key challenges. They mentioned the quality of the stencils; getting the right stencils—their stencils are done by a third party; aperture design; and stencil wear, among others, as issues around this part of the process. This is made more challenging because of the finer pitch and spacing in PCB designs. Specific problems in this regard include complete filling of apertures, paste release, and the large range of component types and sizes and the solder paste thickness requirement on the same design.

Other main issues include the accuracy and repeatability of the equipment, and the characteristics of the solder pastes being used.

Which brings me to our topic for this month’s issue of SMT Magazine. Many studies over the years have found that up to 70% of PCB assembly defects come from the solder paste printing operation. In this issue, we look at the critical issues in the solder paste printing process, and how assemblers can address these challenges to help improve their yield and quality.

To read the full version of this article, which appeared in the December 2017 issue of SMT Magazine, click here.

Share


Suggested Items

Survey: Low-Temperature Soldering on PCBAs

11/14/2018 | Stephen Las Marias, I-Connect007
The majority of the respondents in our survey stated that they expect low-temperature soldering to result in higher quality PCBAs.

Investigation on the Assembly Process for m03015 and a Brief Look at m0201 Components

11/14/2018 | David Geiger, Robert Pennings, and Jane Feng, Flex
Components continue to shrink in the SMT world, and the next evolution of passive components includes m03015 (009005) and m0201 (008004). The m03015 and the m0201 components will see primary adoption in products that require further miniaturization, which would be SiPs. These modules would then be assembled into products through attachment, another assembly, or via other interconnect methods. This article explores the development of an assembly process (SMT only) for the m03015 component.

Alpha Assembly Solutions on Training, Education, and Low-Temperature Soldering

11/07/2018 | I-Connect007 Editorial Team
In this interview, Jason Fullerton of Alpha Assembly Solutions discusses the benefits and challenges of low-temperature soldering. He also highlights the biggest concerns he’s currently seeing in the industry, including young engineers lacking hands-on manufacturing experience and training, voiding and head-in-pillow issues, and low-temperature soldering demands.



Copyright © 2018 I-Connect007. All rights reserved.