开云体育

Michael A. Terrell


1968-03-18

Patent application. I was told that 'Wet Wicking' was used for several years before the dry system hit the market. I used to buy surplus reels of fine braid and dip it into Kester 1544 liquid flux. It worked much better than any dry wick that I tried.



-----Original Message-----

From: Dennis Tillman W7PF <dennis@...>
Sent: Feb 24, 2019 4:22 PM
To: [email protected]
Subject: Re: [TekScopes] Cleaning plug-in contacts

Hi Brian,
I went through a paid one week NASA Soldering School in 1967. It was a requirement for working at Allied Aerospace before I was allowed to solder anything. Early in my career I soldered a few guidance instruments that went into one of the Apollo capsules. The inspector sat next to me as I worked. I stopped after soldering each joint so he could inspect it before allowing me to go on to the next one. This was mission critical man-rated instrumentation I was working on and that is how it was done in those days.

What you are describing is rework. I suspect the requirements are very different than what I was doing. The methods you were taught were probably highly dependent on the kinds of rework you had to perform. It sounds like you took adequate precautions to minimize and localize the abrasion to just the area that you needed.

I did some rework as well. It was always messy business. The PC Boards we worked on often had to be coated with a very thick chemical conformal coating to protect them from all sorts of environmental factors. It was like they were dipped in clear epoxy. In our case we used a soldering iron to soften the coating so we could dig the parts out of it that needed to be replaced.

Solder Wick didn't exist in those days but we had a laboratory wide vacuum system so each technician had a built in high vacuum solder sucker on his desk. It works much better than Solder Wick which leaves a lot of rosin behind that has to be cleaned off. That was another thing that was required. There could be no flux left on a joint when you were done. Each joint had to shine and have a perfectly smooth fillet on both sides of the PC board. Teflon coated stranded wire was all we could use on each board. Each strand had to be visible in the solder joint so the inspector could see it was done perfectly.

What I learned during that one week NASA Soldering School was an eye opener. I came home every day and showed my friend each new joint I had learned how to make that met NASA's rigid standards. We checked every joint we made under an inspection microscope until we knew how to make them perfect every time. I still use all I learned back then every time I solder something today.

Dennis Tillman W7PF ng with an eraser to remove.

Wikipedia: "Gold is a Noble Metal. The noble metals are metals that are

resistant to corrosion and oxidation in moist air... Surfaces of "physically
defined" noble metals (e.g., gold) are easy to clean and keep clean for a
long time."

Caig labs created Cramolin, and DeOxit for cleaning gold contacts of the

residue that might be interfering with the gold making good contact. I have
always been suspicious of Caig Laboratories products because their claims are
mostly marketing "hype" and not based on scientific evidence. In general
their directions are to apply a vapor thin layer of their products to gold
surfaces but they don't offer much help in how to go about doing that for
their liquid products. Their DeOxit wipes seem to be one way to do it and I
do use them to remove dirt and other residue from gold contacts.

Dennis Tillman W7PF