Is there solder for electronic applications that melts at a higher temperature?

tomjelly · Mar 1, 2020

I need to reflow the solder around a heating element contact for a hot laminator shoe, but my soldering iron is not melting the solder. Pretty strange as I've not seen this issue before. Is there a higher temp solder than normal that might have been used in this application? The heating element is on a PC board and bonded to the shoe with silicone, and designed for 300F working temp, so presumably it would never go over 500F which I'm told is the max for silicone. Is there such a thing as high temp solder for electronics?

MichaelP · Mar 1, 2020

Sure. The most common ones are below 400F, but some melt at twice that.

Often, however, all you need is to use a more powerful iron when dealing with large solder joint/high thermal conductance situations.

SVFeingold · Mar 2, 2020

There is, for specialist applications. Common (even most automotive and military) components are built to handle lead-free solder temperatures, usually for 2-3 cycles as per IPC spec. The highest high-temp solder I've seen for electronics (not saying there aren't others) melts around 300°C. Any decent soldering iron will reach that just fine. More likely you either have a cheap iron and/or poor thermal contact.

jim rozen · Mar 2, 2020

What is the heater made of? Is it ceramic?

Why do you want to re-flow the solder?

Can you mark the exisiting solder with a steel scriber, how ductile is it?

There is some chance this is some sort of braze, and not a soft solder.
The nearest braze I could imagine would be Nicrobraze which is a very
high temperature material. But it would be extremely hard and not ductile
at all, a steel scriber would barely make a dent.

The most likely issue is the heater has a huge thermal conductivity and
you would have to get the entire assembly up to re-flow temperature, if it
is a soft solder.

rons · Mar 2, 2020

Those hand held pencil soldering irons are not good.

A solder station like a Weller has 600, 700, 800 degree tips.

Probably a Weller 8200 would transfer enough heat.

Pathogen · Mar 2, 2020

I use solder for operating at 350F

I run my iron at 760F to work with it and use a Kester flux

For your application a micro torch or heat up a solder iron tip with a torch

There's enough solder on it now to work with but if you need a bit more I can send you some

Scottl · Mar 2, 2020

I 100% agree with those who are saying you simply haven't enough wattage. All of that copper is acting as a heat sink. When I've soldered power electronics on a thermal management substrate I had to use a laboratory hot plate, the kind that has a heated surface rather than an open element, to provide preheat. In situations with heat sinking I've used a heat gun to elevate temperature prior to soldering. In your case if you can add extra heat and use a good heavy-duty iron you should be OK. You might want to use a heavy-duty soldering gun instead. I use my old 300+ watt Weller to solder steel socket clips onto a steel rail to hold automotive sockets.

PS: I still have a couple of the old style soldering coppers that you heat over a flame. One of them would make short work of a job like that. I used to use them for things like soldering a different filler neck on a brass radiator tank and still occasionally drag them out where I can't use a torch directly.

jim rozen · Mar 2, 2020

Weller Pyro-Pen (butane powered) with the honking big tip maybe?

Again, if it's so darn tough to melt the joint, why does it need reflow?

tomjelly · Mar 2, 2020

There was no continuity between the connectors on the pc board heating element. I was able to get the correct reading between one connector and the trace immediately adjacent to the problematic solder pad, so that is why I wanted to reflow that joint. I was able to melt the solder by heating a polished piece of copper with a propane torch and holding it to the joint. Unfortunately it just popped off, and with the connector removed from the pad there is no continuity between the pad and the trace just a few MM away from it, so the trace must be fractured right next to the pad. Its hard to see because the pc board heating element is bonded into the heat shoe with silicone and it sits up under the curve of the inside of heat shoe. I tried to get regular solder to stick to the trace but was unable to do so. I wonder what material the trace is made of to make that heating element, it doesn't look like copper necessarily, there are 6 elements across the width of the shoe wired in parallel 177 ohms each, and they are not available separately from the manufacturer of course, only the whole shoe at close to $400. There are a number of these machines available for parts at under $100 on ebay so I'm trying to get one of those people to part one out but it takes a bit of doing to get the part out and the machine weighs too much to economically ship whole so fixing the element would be best if I can get it done somehow. I don't know if a trace repair is possible with whatever that material is.

Chip Chester · Mar 2, 2020

800 F or better is your target for lead-free solder. Hard to find tips that hot for older Weller stations -- there are just a few. Your average small iron from Amazon/ebay that has a digital read-out will do it for electronics components. Treat yourself to some lead-free solder to cap off the transaction, as it doesn't always play nice with the old-school stuff. Some flux for re-flow use, too, a couple rolls of solder wick, and then watch some YouTube vids on the matter. If the board has a solder mask, it will be a surprisingly easy task. Except for seeing the tiny things.

tomjelly · Mar 2, 2020

I have a hakko digital solder station that runs up to 720, but it has a pretty slim tip. It was not able to melt the joint. From what I've read the 60% lead 40% tin is the hi temp stuff. I haven't seen any for sale but have not looked really hard yet. I will say that I am absolute sh*t at soldering and have had terrible luck with weller 8200 guns failing, so I trashed the last one I had. I will find a hotter gun then q tip with isopropyl, scrape off what ever is over the trace, isopropyl again, flux and attempt to solder with the hi temp stuff while holding the connector in place with some of that hi temp tape or some sort of fixture, and then pitch the whole thing across the shop when I fail.

Tony Quiring · Mar 2, 2020

A Weller pistol gun will do the trick.

Cut tip shorter for more watts.

Carefully scrape the area to get to shiny surface then it should "tin" with no fuss.

Sent from my SAMSUNG-SM-G930A using Tapatalk

tomjelly · Mar 2, 2020

Good idea to cut down the tip leads for more heat. Any good source for the proper high temp solder?

Scottl · Mar 3, 2020

tomjelly said:
I have a hakko digital solder station that runs up to 720, but it has a pretty slim tip. It was not able to melt the joint. From what I've read the 60% lead 40% tin is the hi temp stuff. I haven't seen any for sale but have not looked really hard yet. I will say that I am absolute sh*t at soldering and have had terrible luck with weller 8200 guns failing, so I trashed the last one I had. I will find a hotter gun then q tip with isopropyl, scrape off what ever is over the trace, isopropyl again, flux and attempt to solder with the hi temp stuff while holding the connector in place with some of that hi temp tape or some sort of fixture, and then pitch the whole thing across the shop when I fail.

As I recall, 60/40 is what is used for leading in dents and seams in auto body work. It comes in slim bars and any good auto body supply should carry it. Pros don't use plastic filler on high end work and use body solder instead.

Correction: I just did a quick online search and auto body solder is 70/30. You can get 60/40 on Amazon. However, it is actually lower in melting temperature.

Here is a handy chart of alloy vs melting temperature.

https://www.kester.com/Portals/0/Documents/Knowledge Base/Alloy Temperature Chart.pdf

jim rozen · Mar 3, 2020

" I tried to get regular solder to stick to the trace but was unable to do so."

This, with regular rosin flux, correct?

Conrad Hoffman · Mar 3, 2020

This stuff is very strong: Bridgit(R) | The Harris Products Group

Regardless of what you use, you need a high thermal mass tip or the pistol gun. The joint may have failed in the trace, near the joint, and could be impossible to fix.

Chip Chester · Mar 3, 2020

Ask around if any of your friends has an American Beauty iron. Common around stained glass folks, tinsmiths that actually work with tin, etc.

Try some solder wick to get all the solder off, and perhaps try some silver solder for re-attachment. The Bernzomatic Silver Solder at Lowe's for $12 has a melting point of 430F according to their website. It's pretty strong, too.

Cleaning the joint well of flux, foreign solder, and silicone may help with the fix.

tomjelly · Mar 5, 2020

I may have convinced someone to part out the piece I need, if not I'll be giving it a go....I do have some 40/60 tin/lead solder, but it says specifically "do not use on electronics" Looks like it was for plumbing, and has a flux core. Why can't It be used it on electronics??

Chip Chester · Mar 5, 2020

Sure it doesn't say acid core somewhere? That would be an issue for electronics. Or perhaps the flux is somehow incompatible. I guess if they say don't, then don't...

tomjelly · Mar 5, 2020

Oh yes, acid core, that's why I guess.

Is there solder for electronic applications that melts at a higher temperature?

Stainless

Titanium

Aluminum

Diamond

Diamond

Hot Rolled

Diamond

Diamond

Stainless

Diamond

Stainless

Titanium

Stainless

Diamond

Diamond

Diamond

Diamond

Stainless

Diamond

Stainless

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