-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueComing to Terms With AI
In this issue, we examine the profound effect artificial intelligence and machine learning are having on manufacturing and business processes. We follow technology, innovation, and money as automation becomes the new key indicator of growth in our industry.
Box Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
Printed Circuit Board Failures – Causes and Cures
November 23, 2015 | Pete Starkey, I-Connect007Estimated reading time: 5 minutes
Outgassing from via hole during testing with oil.
His surveys on behalf of IPC and NPL had indicated that shorts and open circuits accounted for 27% of PCB problems, and via hole failures for 8%. But solderability was by far the principal cause of failure at 39%. He listed a whole series of bare-board solderable finishes: hot-air solder level, immersion silver, immersion tin, organic solderability protective and electroless nickel immersion gold, and reviewed methods for thickness measurement and solderability determination, as well as showing examples of phenomena such as nickel-footing and solder wicking. Whereas the wetting balance gave the most scientific measurement of solderability, it tended to be found mainly in specialist test laboratories. Willis advocated a simple dot-coalescence test as a practical alternative, for which a small test-coupon could straightforwardly be incorporated into the PCB panel design. In the investigation of “black pad” failures, he demonstrated what could be revealed by scanning electron microscopy of electroless nickel surfaces after chemical removal of the gold layer from an ENIG finish.
Short circuits or low-resistance current leakage paths could be formed in service by electrochemical migration of copper, and Willis showed examples of dendritic growth across the PCB surface and conductive anodic filament (CAF) growth from the barrels of plated-through holes along glass-fibre bundles. It was critical that assemblies were free from ionic contamination after the soldering and post-soldering cleaning processes, particularly if the work was to be conformally coated, and Willis described techniques for measuring ionic contamination and interpreting the results.
Two particular defects had been associated with the introduction of lead-free soldering: copper dissolution and pad cratering. In the former case, if there was no electroless nickel barrier layer, there was a tendency for copper to be dissolved by the solder, particularly if the solder had a high silver content, in some cases drastically reducing the effective thickness of surface-mount pads, and in the latter case for a cohesive failure to occur in the resin under the pad as a result of the increased brittleness of laminates formulated to withstand lead-free processing temperatures.
Finally, Willis referred webinar attendees to the NPL Process Defects Database, http://defectsdatabase.npl.co.uk, a searchable on-line compilation of actual soldering process defects. For each defect entry, there was a link to a relevant report where appropriate, with free access to over 100 NPL reports on various aspects of reliability characterisation.
There was great interest in this webinar. An enormous amount of relevant information was shared, and the question and answer session ran on well over the nominal finish time in response to attendees’ specific queries. A great credit to SMART Group, whose aim has always been to promote the advancement of the electronics manufacturing industry through the education, training and notification of its members in surface mount and related assembly technologies, and to Bob Willis himself for generously sharing his know-how.
Page 2 of 2Suggested Items
Indium Experts to Present on High-Temperature, Lead-Free Solder Paste and High Reliability Liquid Metal Alloys Poster at ECTC
05/16/2024 | Indium CorporationIndium Corporation Research Associate Kyle Aserian will deliver a presentation at the 74th Electronic Components and Technology Conference (ECTC) on May 31, in Denver, Colorado.
Indium Experts to Present at Electronics in Harsh Environments SMTA Conference
05/13/2024 | Indium Corporationndium Corporation Technical Manager for Europe, Africa, and the Middle East, Karthik Vijay, will deliver a technical presentation and Indium Corporation Senior Technologist, Dr. Ronald Lasky, will deliver both a workshop and technical presentation at the Electronics in Harsh Environments SMTA Conference on May 14-16 in Copenhagen, Denmark.
Connect the Dots: Designing for Reality—The Pre-Manufacturing Process
05/08/2024 | Matt Stevenson -- Column: Connect the DotsI have been working with Nolan Johnson on a podcast series about designing PCBs for the reality of manufacturing. By sharing lessons learned over a long career in the PCB industry, we hope to shorten learning curves and help designers produce better boards with less hassle and rework. Episode 2 deals with the electronic pre-manufacturing process. Moving from CAD (computer-aided design) to CAM (computer-aided manufacturing) is a key step in PCB manufacturing. CAM turns digital designs into instructions that machines can use to actually build the PCB.
AIM Solder Signs Shinil Fl Ltd. as New Distributor for Korea
05/08/2024 | AIM SolderAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce a new distribution partnership with Shinil Fl Ltd., a prominent supplier of technological solutions in the SMT and semiconductor sectors.
Indium Corporation to Showcase HIA Materials at ECTC
05/07/2024 | Indium CorporationAs an industry leader in innovative materials solutions for semiconductor packaging and assembly, Indium Corporation® will feature its advanced products designed to meet the evolving challenges of heterogeneous integration and assembly (HIA) and fine-pitch system-in-package (SiP) applications at the 74th Electronic Components and Technology Conference (ECTC), May 28‒31, in Denver, Colorado.