Originally published at: https://contextualelectronics.com/topic/3v3-regulator-component-placement/
In this video, Chris repeats some of the work we already did in the first video of the last section, but actually hooking the parts in to the rest of the schematic, and doing so while everything is in place. Links we discussed in this video: TPS62821 datasheet Some of the topics covered: What are…
One thing that I’m finding interesting about this layout is that you don’t seem at all bothered about putting components on both sides of the board, even quite big components. How big do things have to get before you have to start thinking about adding an adhesive layer to stop back-side components falling off when you reflow the front-side?
Depends on what you’re referring as “front” and “back”. I plan to reflow the “front” side first (the side with the SD card holder and the connectors). The mechanical elements could have some problems, but we can use glue or even polymide tape to hold them on when reflowing the other side. The other components on there (caps, resistors, even the battery charge controller) should all be small enough to be held on with the surface tension of of the solder.
Which components stick out (ha) as the most problematic in your mind?
On the “top side” (is that less ambiguous?), you’ve got the card holders, the mezzanine connector and those solder-in standoffs (would they be reflowed, or can you hand solder them afterwards?). They all look “falloffable” to me. On the “bottom side” you’ve got the cellular modem and the nRF52840.
I guess I was thinking about more automated assembly, but for prototyping doing the “top side” first and taping the mechanical stuff in place sounds like a good solution!
I guess it depends
Are you doing a design to learn as a hobbyists or as a professional. As a professional it should be made to comply with automated processes
My eyesight is not perfect any more, so cannot assembly without the microscope. So even some hobby projects I spend a little more time in layout and get them run by JLCpcb who does cheap assembly (so no longer have the escuse that I need to mount the boards to get cracking on the project)
Yeah, sending out for assembly, they would able to do this with an adhesive application, likely.
But with the density we’re looking at here…it’s not really avoidable. So the weight of the problem would really be put on a manufacturing engineer. Whether or not that’s fair, or whether it would fly in production, would come down to the CM you work with.
For this, I am the CM, and I say it’s ok for now! 
Yes, and sometimes it better to do as you did, just to get the process moving. Spending time on the important stuff