procedure for unsealing a soldered RF can? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2018, 06:55:41 pm
content: So the RF cans in my wideband preamp for the hp70000 are soldered shut.I have soldered my own enclosures before but I typically use some kind of thermal isolation between the electronics and the thing to be soldered.Does anyone have a good safe method of opening the RF cans to have a look inside of them?I am worried because these do not look like they have good thermal isolation to the electronics, its just a lid soldered directly to a RF can. I assume they might be using highly conductive ceramic PCB and also using the can as a heat sink.I thought to either:1) Use a gas torch to heat the center of the top till I can slide it off2) try to heat up a large chunk of metal and press it to the top to avoid direct flame.. I thought it might have good thermal conduction. Recommendations and temperature It looks gold plated so I figure its regular electronics solder?They are like 1.5x2 inchesDo you need to do anything weird like submerge them in water to keep the bottom cold or something? Or use an aluminum plate etc?

author: CJay
author_rank: Super Contributor
timestamp: September 05, 2018, 08:33:38 pm
content: Depends what the can is like, I've removed a few but with varying success.The ones I've had most luck with were on crystal filters, I managed to remove as much solder as I could and was then able to slip a very fine craft knife blade into the seal and pried it apart ever so slightly and working my way round the edges, where there was still solder I couldn't 'cut' I removed it with solder wick and solder sucker.If it doesn't need repairing then leave it well alone.

author: Wolfgang
author_rank: Super Contributor
timestamp: September 05, 2018, 09:46:40 pm
content: Hi,I use an electric blowtorch set to a temp just a little above the melting point of the solder.Plan B is a heated plate (just like the cheap chinese ones for removing mobile phone display glass)Place the box on it, set to 200°C, wait until you see solder flow, rip the lid off carefully.

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2018, 09:47:51 pm
content: So you don't have to worry about a high thermal mass and thermal conductivity to melt the solder and lid as quick as possible, heating the can as little as possible?I find it hard to imagine with an aluminum block but I thought there might be general procedure.I figure then I will put a cartridge heater in an aluminum block.I will try to test it on the bench with another SA since the power is labled though. just thinking ahead so I have good workflow

author: Wolfgang
author_rank: Super Contributor
timestamp: September 05, 2018, 09:49:26 pm
content: I dont worry about that so much, because tinplate is a bad heat conductor. In the cases where I needed to do it it worked.

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2018, 09:50:55 pm
content: Quote from: Wolfgang on September 05, 2018, 09:49:26 pmTinplate? the roof is not aluminum sheet coated to be easily solderable? It is supposed to work to 2.7GHz.

author: Wolfgang
author_rank: Super Contributor
timestamp: September 05, 2018, 10:15:42 pm
content: I dont have this machine but I doubt it. You can try - is it magnetic ? If yes, its tinplate

author: Beamin
author_rank: Super Contributor
timestamp: September 05, 2018, 11:33:04 pm
content: Quote from: coppercone2 on September 05, 2018, 09:50:55 pmIf it is aluminum solder definitely won't stick to it. It runs off like water on Teflon. I don't think there are any metals that you could use as solder with aluminum. When solder sticks to copper it or any type of braze it forms an alloy even though it doesn't look like it.

author: ogden
author_rank: Super Contributor
timestamp: September 05, 2018, 11:37:55 pm
content: Quote from: coppercone2 on September 05, 2018, 09:50:55 pmAluminium? - Maybe you just share photo of the thing you are talking about?

author: tautech
author_rank: Super Contributor
timestamp: September 09, 2018, 08:34:48 pm
content: Tin snips or Dremel.

author: coppercone2
author_rank: Super Contributor
timestamp: September 09, 2018, 08:52:06 pm
content: its like a milled enclosure with a plate soldered on top. I never saw something like it before.

author: ch_scr
author_rank: Frequent Contributor
timestamp: September 09, 2018, 09:10:17 pm
content: I can relay what was recommended in another post on this forum, and has worked beautifully for me so far: dragging the backside of a utility knife along the solder joint, it works like a planer blade, making little shavings of tin. I have successfully opened an oven oscillator module (made from a milled base and heavy tinplate parts) and a (thin walled) soldered HF can with this method.

author: eb4fbz
author_rank: Regular Contributor
timestamp: September 09, 2018, 10:30:40 pm
content: Quote from: coppercone2 on September 09, 2018, 08:52:06 pmProbably a laser welded cover. I have seen those in microwave modules.

author: coppercone2
author_rank: Super Contributor
timestamp: September 09, 2018, 10:37:54 pm
content: oh shit you think thats an actual weld?

author: eb4fbz
author_rank: Regular Contributor
timestamp: September 10, 2018, 09:58:51 am
content: Quote from: coppercone2 on September 09, 2018, 10:37:54 pmPost a photo

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 10, 2018, 10:19:50 am
content: Metcal or JBC iron with big fat tip.If the solder is leadfree, go round and flood some leaded into it to reduce melting pointDesolder braid to remove as much solder as possible.You can then usually just prise it off as the remaining solder will be thin & weak.

author: KJDS
author_rank: Super Contributor
timestamp: September 12, 2018, 09:59:58 am
content: punch a little hole, then slide a scalpel blade in and peel it off.

author: Beamin
author_rank: Super Contributor
timestamp: September 13, 2018, 02:19:20 am
content: Quote from: mikeselectricstuff on September 10, 2018, 10:19:50 amI always thought "prise" was something old dart and ausie people said but when typed they say "pried"; what a whacky word to use.A prize is something you win. A pry is something you try hard at. Yes I'm telling the English how to speak English the irony is not lost.I would like to see electricmikes stuff use a "destructotron" to unsolder it.