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Soldering photo etched parts

Soldering photo etched parts

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jack Armitage18/04/2015 00:03:18
12 forum posts
1 photos

Good evening, I started on a new project 2 weeks ago and I'm totally stuck..

Its my first time modelling using photo etched brass, and sticking them together is proving to be a real pain..

I have tried using cyno and epoxy and its a bit hit and miss

.I have tried soldering a couple of pieces, but the solder just isn't sticking properly to the surface of the parts...It just creates a lumpy mess instead of a smooth soldered joint, and often just falls off when it goes cold.

I'm using a 25 watt soldering iron and flux cored solder..I have soldered hundreds of items made out of tin over the last 30 years using similar soldering irons and solder without ever having a problem.

I thought soldering photo etched brass would be a very similar process to soldering tin, but apparently it isn't..

.Does anybody have any suggestion on what I could be doing wrong regarding the soldering?

Thanks in advance

cymaz18/04/2015 04:51:33
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8651 forum posts
1175 photos

There's a bit of know how to it apparently.....try here if this helps

jack Armitage18/04/2015 07:16:53
12 forum posts
1 photos

Thanks Cymaz, I have seen this method used before with brass..

The problem is, that some of the photo etched parts are so thin and delicate, such as the part in this picture..This little piece in the picture is about 0.25mm thick..

dscn0742.jpg

Any attempt to rub the mating surfaces with something abrasive, simply bends it badly.

To make matters worse, there are 100's of these, and similar pieces to join together, and they are left in their natural colour afterwards and not painted.

If its a protective coating on the brass that's causing the problem, then maybe there is some type of cleaning product that can be used to dip them in to remove it?

cymaz18/04/2015 07:28:29
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8651 forum posts
1175 photos

Hell, that is small.

Maybe a trawl through a model railway forum ?

Dave Hopkin18/04/2015 07:44:23
3672 forum posts
294 photos

When I use them on scale RC Ships, I use a plasticine jig to hold them together adjusting them so the edges butt up well, then use meduim CA along the seam, remove the plasticine and CA the bit letf

jack Armitage18/04/2015 07:56:49
12 forum posts
1 photos

Cheers Dave..They actually are parts from a large model ship that I have just started on. A Trumpeter HMS Nelson.

I was struggling using various clamps and tweezers to hold the parts together.

When you use this method, do you paint the parts afterwards?

My original intention was to leave all the brass parts unpainted so they would really stand out, buy CA does tend to dry a white ish colour

Dave Hopkin18/04/2015 08:30:15
3672 forum posts
294 photos

Yes paint after assembly - you can try to clean up the white CA bloom with a flat needle file - but yiu need the patience of job and the steady hand of a eye surgeon!

An alternative is paint the brass frames then very gently scrape of the paint just on the corner of the inside of the frame to expose as very fine brass line

jack Armitage18/04/2015 10:02:11
12 forum posts
1 photos

Tell me about it Dave..

In 2 weeks, I have managed to build up 6 AA turrets!

Engine Doctor18/04/2015 11:01:11
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2296 forum posts
27 photos

Hi Brass should solder really easily . There must be a film or lacquer used in the etching process stopping the solder from attaching. .Have you tried washing/cleaning in cellulose thinner or similar? Best try on some scrap first though. what solder are you using ? Some of the newer stuff needs a higher temp to flow, good old EU . Multicor electrical solder is a good flowing solder and is still available . 60/40 lead and tin mix is what to look for .i use it for making fuel tanks and its fine with a 55watt iron. Avoid the Chinese stuff in kit from Aldi and the like as it doesn't like flowing and sets with a matt sort of finish, horrible stuff. It may be that your iron is not powerful enough . Try a bigger wattage iron and just file the tip to a small point .

Just a thought about gluing the parts instead of soldering. If you use the thicker grade cyano thats slightly slower it will /should set clear.The Glue shop ,they used to be called 5 Start products sell a kicker that doesn't whiten the glue or discolour the glue . 

Edited By Engine Doctor on 18/04/2015 11:07:51

Dave Hopkin18/04/2015 12:18:47
3672 forum posts
294 photos

ED

Etched brass for scale warhip fittings is thousands of an inch thick - if you go near it with anything more than a 25w iron it distorts - breath heavy and it blows away!

Dont use resin core solder the flux powder inside goes to a glass like layer and the brass is too fragile to allow cleaning

You need flux free low melt solder (140 degrees) - liquid acid based flux -

Position the parts together - paint the flux along the join - collect some solder on the end of the iron and wipe it down the join

Biggles' Elder Brother - Moderator18/04/2015 15:40:17
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Moderator
15748 forum posts
1460 photos

My other hobby is 'O'-gauge model railways - so photo-etched brass is familiar territory for me!

1. ED is correct - they often do not clean off the resist. This is why you can't get your solder to flow.

2. Get yourself one of these - de rigor in model railway circles! Gently rub the surfaces you intend to solder and then clean with a little acetone. Note only clean where you want the joint - the remaining surface coating is a good way to control exactly where you solder will go!

3. Dave is spot on in my experience - use a weak acid flux - like 9% phosphoric which you can get here - and a straight low melt solder without flux. Rinse the part under running water after soldering to remove any traces of acid.

Do that and your worries will be over!

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