More Stencil Questions (and the Answers!)


Reading time ( words)

My March The Short Scoop column, "10 Common Stencil Questions," brought in a slew of new questions from customers. Do you know the answers?

1. What are my fiducial choices and how do they differ?

Yes, stencils require fiducial markings to make sure the stencils are aligned correctly to properly print the pattern, as most people know. What they might not know is that there are actually several types of fiducials, and when you select a stencil, you must choose one of them.

The fiducial choices available today depend on the stencil manufacturer you use and/or your own requests, but truthfully, there really are only two predominate types. One is half-etched and filled, which have an etched pocket in the stencil at the fiducial location that is then filled with a black epoxy. Ultimately, these offer one of the strongest contrasts for the visual printer cameras, but they are an older technology and often, the epoxy falls out at the least opportune time. 

The other predominate type is a laser tattooed fiducial, which is a relatively newer technology. These are applied by a laser (usually the same one that cuts the apertures for a laser stencil).  In this technology, the laser truly burns the fiducial to the stencil.  The benefits are that it lasts forever and the epoxy doesn’t fall out. Laser tattooed fiducials provide the tightest location tolerance of any fiducial and most companies are moving toward this technology. It is imperative to note, however, that the darkness of the laser fiducials have varying contrasts from one stencil to another. This is usually due to the material type, the pattern density of the stencil, laser type, and several other factors. I mention this because some printers struggle with the contrast that is less than what they might have had previously in the half-etched and filled fiducials.

2.  What CAD information and files are needed to make my stencil and how will I receive my check plots?

These are very important questions so that manufacturers know what to expect and don’t waste time or effort preparing something that isn’t usable by the stencil manufacturer. Additionally, they don’t have to go back to a format that is different from what is usually done. We use IGI and Valor, which are software systems that can custom design each stencil.

Read the full column here.


Editor's Note: This column originally appeared in the July 2014 issue of SMT Magazine.

Share

Print


Suggested Items

The iNEMI 2019 Board Assembly Roadmap

06/01/2020 | Pete Starkey, I-Connect007
iNEMI continues to publish chapters of its 2019 Roadmap and recently presented an overview of its Board Assembly Roadmap Chapter in a webinar prefaced by Grace O’Malley, vice president of global operations. The new chapter is just the latest addition to this global effort from 23 working groups contributing expert input from all aspects of the electronics industry.

This Month in SMT007 Magazine: How Engineers Can Use SPI Tools for Verification

05/06/2020 | Nolan Johnson, I-Connect007
Koh Young’s Ray Welch and Brent Fischthal detail how engineers can work with SPI tools to verify how small they can go in component size with their solder paste application, and how the company’s SPI equipment is helping not only to verify but also to help drive the development collaboration between solder paste and stencil printer manufacturers, and inspection tools and software.

Stencil Cleaning Update With Tom Forsythe

04/09/2020 | Real Time with...IPC
In this video interview from the show, Pete Starkey and Tom Forsythe, executive VP of KYZEN, which celebrated its 30th anniversary, discuss the practicalities of stencil cleaning and describe the characteristics and capabilities of KYZEN's newest versatile stencil cleaning product.



Copyright © 2020 I-Connect007. All rights reserved.