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QFN is (very, very slowly) opening up to the idea of "wettable flanks", which is increasing the reliability of QFN soldering anyway... which is increasing the o

QFN is (very, very slowly) opening up to the idea of "wettable flanks", which is increasing the reliability of QFN soldering anyway... which is increasing the opportunity of "side-soldering" QFN packages. https://www.ti.com/document-viewer/lit/html/SSZTBN6 https://www.ti.com/document-viewer/lit/html/SSZTBN6 Here's to hoping for more manual soldering techniques to work into the future! We all know that these parts are getting extremely small and harder to work with, but its still clearly possible to make devices. But yeah, QFNs, if this wettable-flank trend continues, could be quite reliably soldered and inspected from the sides soon. The needs of the high-reliability automotive industry to create an inspection methodology outside of X-Rays is driving this change. ------------ Glad to hear that your technique worked in any case. I wouldn't have tried that, but maybe I'll try it once next time I have a hot-air gun out and a DFN part to try it on. EDIT: Note that Microchip apparently has some DFNs that also have wettable-flanks: https://www.microchip.com/en-us/about/media-center/blog/2022/dfn-packages-with-wettable-flanks https://www.microchip.com/en-us/about/media-center/blog/2022...

jamesy0ung 3y ago
That's very interesting, I've always found QFN to be annoying to work with
OJFord 3y ago
> The needs of the high-reliability automotive industry to create an inspection methodology outside of X-Rays is driving this change. Why is that a particular requirement? Or is it just nobody wants/rather avoid x-ray, and automotive has greater need for inspection at all?
- cinntaile 3y ago
  It's probably cost? X-ray is an expensive technique.
  - OJFord 3y ago
    Yeah but that's not specific to automotive right, that's what I meant. I was trying to understand whether they meant the need for inspection or the non-X-ray was the particular concern in the automotive industry.
- cpgxiii 3y ago
  Automotive has much higher reliability requirements than consumer devices, and since solder failures are probably the leading cause of failures using *FN parts, they want to have effective inspection methods to ensure devices are assembled properly. When you use parts with leads, you can easily perform all of your QA checks using machine vision (all all the components in the right place, are they correctly aligned, are the connections properly soldered, etc), but if you use parts with no leads and the solder connections are hidden, you need a separate X-ray check which takes additional time, assembly-line space, and money. Depending on the components in question, it may also be tricky to get enough contrast in the X-ray image to identify defects.

jamesy0ung 3y ago

That's very interesting, I've always found QFN to be annoying to work with

OJFord 3y ago

> The needs of the high-reliability automotive industry to create an inspection methodology outside of X-Rays is driving this change. Why is that a particular requirement? Or is it just nobody wants/rather avoid x-ray, and automotive has greater need for inspection at all?

cinntaile 3y ago
It's probably cost? X-ray is an expensive technique.
- OJFord 3y ago
  Yeah but that's not specific to automotive right, that's what I meant. I was trying to understand whether they meant the need for inspection or the non-X-ray was the particular concern in the automotive industry.
cpgxiii 3y ago
Automotive has much higher reliability requirements than consumer devices, and since solder failures are probably the leading cause of failures using *FN parts, they want to have effective inspection methods to ensure devices are assembled properly. When you use parts with leads, you can easily perform all of your QA checks using machine vision (all all the components in the right place, are they correctly aligned, are the connections properly soldered, etc), but if you use parts with no leads and the solder connections are hidden, you need a separate X-ray check which takes additional time, assembly-line space, and money. Depending on the components in question, it may also be tricky to get enough contrast in the X-ray image to identify defects.