Circuits Assembly Online Magazine - Features

Features Articles

Peter Bigelow Faced with a host of software and machines, is a data-driven electronics shop a pipe dream?

Over the December holidays I had an epiphany: My company is just like a Christmas tree!

My epiphany occurred amid the annual ritual of putting up holiday decorations. Like every year over the past decades, a freshly cut tree is proudly lugged into a prominent place in the house. In a water-filled stand the tree majestically fills the room with a rich pine smell as decorations are pulled from storage and readied to adorn it. When decorating a Christmas tree, the first step is putting the lights on. And every year that begins by taking lights that worked flawlessly the previous year, unraveling them and testing they still work. And like all previous years, the result is the same: most light, some do not.

This leads to the next ritual: figuring out why. This entails fidgeting with bulbs and fuses, and hours lost determining whether it would be easier to just replace one of the strings. Even with new lights, however, the problem can occur, prompting a similar ritual of triage, exploration, frustration and finally, success. “Success” often means (reluctantly) living with a tree that may have something like 588 of the 650 lights working. In the end, creative placement of decorations to camouflage the missing lights is an invaluable talent.

Mike Buetow With every Apex comes an outpouring of new standards, and this year’s conference was no exception.

As the demands of PCBs for automotive applications assert themselves as a unique class, the industry standards are being adapted in sync. To that end, IPC-6012, the longstanding bare board qualification spec, now has an automotive supplement, reflecting the “superclass” of reliability for that sector above and beyond Class 2.

Given that auto electronics are shrinking, the IPC task group has eliminated visual inspection in favor of AOI on all layers and recommends use of AVI (automated visual inspection) of the finished PCB.

The cleanliness testing requirement has also been rewritten. The automotive addendum includes a recommendation of tests to be used in Production Part Approval Process (PPAP) documentation.

0201mm chip capacitors and resistors are entering production now in advanced package-in-package modules and should soon become widely used in ordinary printed circuit board designs.

Embedded RF and related materials will aid the 5G rollout.

Martin Wickham Measure changes in package dimensions during NPI.

David Bernard Use partial CT to reveal trace discontinuities at incoming inspection.

In last month’s column, I suggested using x-ray inspection equipment more typically used for the investigation and quality control of assembled PCBs to check bare boards ahead of their use in assembly. Such equipment is often already onsite and readily available to the assembler. The benefits of enhanced magnification and resolution this equipment can usually offer toward inspection of representative bare boards ahead of assembly is, I contend, an opportunity to provide additional confidence that all is well in the bedrock of PCBA. Furthermore, the cause of any future issues, if they occur, can be more easily narrowed down to the assembly process, design or components. The example I gave related to the possible issue of poor drilling quality in the board vias and how, in x-ray images, the plating variability can be readily seen, especially if the via is buried within the board and optical inspection is not possible. Variable plating quality, however, such as voiding in the central termination of a QFN (see “QFN Inspection: Don’t Forget the Edge!” December 2018 column), can often be relatively obvious for an operator to see when it occurs in the x-ray image such that if it is not present and all looks consistent and appropriate, then other subtler issues may not be considered fully, or missed entirely.