This Month in SMT007 Magazine: Robustness Is Not the Same as Reliability


Reading time ( words)

Bob Neves discusses a disconnect he sees in reliability testing between what’s being tested and what happens out in the field, as well as why most reliability tests these days should instead be considered robustness tests.

Nolan Johnson: What are the current dynamics in assembly reliability?

Bob Neves: My history and focus are primarily within the electronics industry surrounding PCBs. My customer base at Microtek, and for testing and evaluation, are the suppliers to the PCB manufacturers, the PCB manufacturers themselves, and the users of PCBs. When we talk about testing, most people who buy PCBs look at the PCB like they would look at a resistor or capacitor—it’s just another component on their build list. The truth is that you really can’t treat the PCB as a component. You need to look at it as a very complex subsystem like you were buying a power supply or some other multi-component assembly that did something for you rather than just a single attribute component like a capacitor or resistor.

The PCB is relied on for passing signals between components and isolating signals from places they’re not supposed to be. When things go bad in an electronics assembly, those are typically the areas where you start looking. Is the signal getting to the correct spot, or are we losing signal some place where we’re supposed to have a signal? A lot of problems that I’ve experienced have to do with the fact that something’s gone wrong in the interconnection or isolation process on the PCB. Engineers come to me, saying, “If I press down on this component, it works,” or, “If I heat it up with a hot air gun, my system works. But if I take it off, it doesn’t work anymore.” That’s where a lot of failures end up being PCB related.

Reliability starts for a product after the component attachment process. After you’ve put all the components on, changed anything that was bad, tested it, and it’s ready to put it in the field, that’s when reliability starts. Any reliability you’re testing—whether it’s on the bare PCB, a component, or the entire assembly— needs to have some sort of simulation that shows that it’s gone through this component attachment process, getting you all the way up to the point of where it would be going out the door. That’s one feature that not everyone does before testing. A lot of people will take a component and then do testing on that component as it comes in the door, or they’ll electrically test a PCB before component attachment and say, “Everything’s great.” But any type of testing that you do to see how long your product might last needs to have some sort of simulation of the soldering process before testing. That simulation also needs to include the rework and repair part of the component attachment process.

To read this entire conversation, which appeared in the September 2020 issue of SMT007 Magazine, click here.

Share

Print


Suggested Items

Meet Christine Davis, I-Connect007 Columnist

12/23/2020 | I-Connect007 Editorial Team
Meet Christine Davis, one of our newest columnists! Christine will share her expertise and lessons learned through her journey as one of the few women in the electronics industry to found and run her own company.

SMTA Europe Solder Finish Webinar Addresses Defects Causes and Cures

12/14/2020 | Pete Starkey, I-Connect007
“What is your most common PCB problem?” A survey conducted by Bob Willis had revealed finish solderability to be the predominant contender, and it was clear that the choice of solderable finish applied to surface mount boards could have a significant effect on the assembly yield and cost of the final circuit. SMTA Europe organised an informative and enlightening webinar this month entitled “Guide to PCB Solder Finishes—Process Defects Causes and Cures,” with soldering specialist Bob Willis as presenter.

What Is Digital Twin Technology, and Why Is It So Important?

09/09/2020 | Happy Holden, I-Connect007
Happy Holden describes how Siemens' 12-part webinar series, “Implementing Digital Twin Best Practices From Design Through Manufacturing,” is an excellent series designed to educate the electronic manufacturing engineer on the progress of using a digital thread to improve products and performance.



Copyright © 2021 I-Connect007. All rights reserved.