-
- News
- Books
Featured Books
- pcb007 Magazine
Latest Issues
Current IssueThe Growing Industry
In this issue of PCB007 Magazine, we talk with leading economic experts, advocacy specialists in Washington, D.C., and PCB company leadership to get a well-rounded picture of what’s happening in the industry today. Don’t miss it.
The Sustainability Issue
Sustainability is one of the most widely used terms in business today, especially for electronics and manufacturing but what does it mean to you? We explore the environmental, business, and economic impacts.
The Fabricator’s Guide to IPC APEX EXPO
This issue previews many of the important events taking place at this year's show and highlights some changes and opportunities. So, buckle up. We are counting down to IPC APEX EXPO 2024.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - pcb007 Magazine
All About Flex: Flexible Circuit Fabrication and Cleanroom Manufacturing
May 30, 2016 | Dave Becker, All Flex Flexible Circuits LLCEstimated reading time: 1 minute
Facility cleanliness is a vital part of process control for flexible circuit fabricators. As higher density requirements continue a relentless drive toward finer traces and spaces, particles and foreign material can cause problems in a number of operations. A particle can cause conductor width and spacing issues at imaging. Conductive material can cause current leaking when trapped under a coverlay or embedded in solder mask. Dirt, dust, or other unintended material may reduce layer-to-layer adhesion. Engineering models suggest hair and fibers can affect insulation resistance and impedance. How big does a particle need to be to cause issues? Consider that typical outdoor ambient air has a normal distribution of particles that can be as small as 0.5 microns and as large as 16 microns. An ultra-high-density flexible circuit might get to 25 micron spacing.
Roughly speaking, one 7−8 micron particle could cause a conductor width and spacing quality criteria violation if it landed on coated resist, or on the photo artwork, or is deposited directly on the photo-sensitive resist during image exposure. With circuitry at ultra-high density, particles in ambient air might cause issues, however, particle size is not the only factor. Quantity and/or density of particles is also a consideration. Ambient air contains 35 million particles per cubic meter, so in an uncontrolled environment, thousands of particles might easily be deposited in a small area. And even if particles don’t settle on material, they can refract collimated light sources that are often used during exposing for creating the circuit image.
These particles also accumulate on work surfaces and are a risk to contaminate in-process materials or operators. It is certainly fair to say the biggest source of contamination is not from ambient air, but the human operator. Human hair is approximately 60 microns in diameter and can be several millimeters in length or longer.
Editor's Note: This article originally appeared in the May 2016 issue of The PCB Magazine.
Suggested Items
AIM to Highlight NC259FPA Ultrafine No Clean Solder Paste at SMTA Wisconsin Expo & Tech Forum
04/18/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce its participation in the upcoming SMTA Wisconsin Expo & Tech Forum taking place on May 7 at the Four Points by Sheraton | Milwaukee Airport, in Milwaukee, Wisconsin.
Hentec/RPS Publishes an Essential Guide to Selective Soldering Processing Tech Paper
04/17/2024 | Hentec Industries/RPS AutomationHentec Industries/RPS Automation, a leading manufacturer of selective soldering, lead tinning and solderability test equipment, announces that it has published a technical paper describing the critical process parameters that need to be optimized to ensure optimal results and guarantee the utmost in end-product quality.
Empowering Electronics Assembly: Introducing ALPHA Innolot MXE Alloy
04/16/2024 | MacDermid Alpha Electronics SolutionsIn the rapidly evolving electronics industry, where innovation drives progress, MacDermid Alpha Electronics Solutions is committed to setting a new standard. Today, we are pleased to introduce ALPHA Innolot MXE, a revolutionary alloy meticulously engineered to address the critical needs of enhanced reliability and performance in modern electronic assemblies.
New Book on Low-temperature Soldering Now Available
04/17/2024 | I-Connect007I-Connect007 is pleased to announce that The Printed Circuit Assembler’s Guide to… Low-temperature Soldering, Vol. 2, by subject matter experts at MacDermid Alpha Electronics Solutions, is now available for download.
Inkjet Solder Mask ‘Has Arrived’
04/10/2024 | Pete Starkey, I-Connect007I was delighted to be invited to attend an interactive webinar entitled “Solder Mask Coating Made Easy with Additive Manufacturing,” hosted by SUSS MicroTec Netherlands in Eindhoven. The webinar was introduced and moderated by André Bodegom, managing director at Adeon Technologies, and the speakers were Mariana Van Dam, senior product manager PCB imaging solutions at AGFA in Belgium; Ashley Steers, sales manager at Electra Polymers in the UK; and Dr. Luca Gautero, product manager at SUSS MicroTec Netherlands.