Ten Useful Things

For those who can't work fast enough

Seriously my view is that if it can stand wave soldering, it doesn't need a heat shunt!

Neil

Posted by Neil Wyatt on 19/01/2018 20:38:06:

Er .... who's soldering are we talking about here?

Neil, I was being taught to teach to MilSpec standards, the standards came from NASA, they were high. For the teachers they were a bit higher.

A heat shunt was mandatory on many components. Omit it and get the dreaded F on the course report. Many components were actually soldered in an I/R oven. The name of the game was High Reliabilty Soldering so every precaution was taken to assure as near perfect a result as humanly possible.

If you were on an Apollo moon mission then a dry joint could really ruin your day!

So how many people used to use 'stand-offs' under their transistors? I just did a search and no response so looks like a photo session in the workshop. I must be showing my age as latest job is a Marshall Valve amp for a muso mate.

* Danny M *

I'm prepared to believe transistors were more delicate in the days when they were made of geraniums, but the likes of stand-offs, tag-strips and bent over leads were old-fashioned in the 1980s!

Neil

https://www.youtube.com/watch?v=8WhAT_OGDzg

Absolutely .... that's where I started and picked up the heat-sink habit - which I still use. You could fry germanium transistors and diodes by walking within three feet with a hot iron.

Incidentally - at least in the old days (1970's) - NASA was very negative about the use of double-sided PCBs and, if they were used, demanded that all through holes (vias) be plugged with solid wire. Somewhere I still have a copy of the old NASA soldering standard.

Lol, but you require a solder sucker with an all metal body (hopefully grounded) as the plastic ones could make an impressive electrostatic spike as the plunger retracted. They were also banned from my workplace for this reason

(I was working to MilSpec so every precaution was taken regarding reliability of the assembly)

* Danny M *

Not at NASA but when we produced designs for low volume in house pcb manufacture & assembly everything that required double sided boards had no plated vias and was produced with soldered wire links (or veropins) between the top and bottom layer, always sited outside the outline of any component (nothing under IC's for example) and all components other than these links were only soldered on the bottom side. The component pads being deleted from the top layer to avoid any wicking and to aid any further rework.