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Capsule damage during soldering

 

Thanks! Why do the jigs always have smaller holes through the bottom? I could see it making sense in a blind hole situation so the part would slide in and out without air compression/rarefaction, but why in a jig like that?

On 11/8/23 05:42, Nick Roast wrote:
This is the jig and heatsink we use for soldering 10 mm capsules. The loose piece is held in place with elastic bands to keep the capsules steady and in good thermal contact with the sink.? We have been using lead free solder for many years, its not as shiny and can often look like a dry joint, but it has been problem free.
 

So the diaphragm isn¡¯t pressured when you insert the capsule into the hole

On 8 Nov 2023, at 17:50, Casey via groups.io <mbuilders@...> wrote:

?Thanks! Why do the jigs always have smaller holes through the bottom? I could see it making sense in a blind hole situation so the part would slide in and out without air compression/rarefaction, but why in a jig like that?

On 11/8/23 05:42, Nick Roast wrote:
This is the jig and heatsink we use for soldering 10 mm capsules. The loose piece is held in place with elastic bands to keep the capsules steady and in good thermal contact with the sink. We have been using lead free solder for many years, its not as shiny and can often look like a dry joint, but it has been problem free.
 

Thanks -- but in the jig he posted it looks like you set the capsules in the slots and then put the enclosing piece in place, i.e. you're not pushing them into the hole? Maybe just to make it easier if you don't feel like taking the jig apart to swap out capsules?

On 11/8/23 10:08, jack wrote:
So the diaphragm isn¡¯t pressured when you insert the capsule into the hole
On 8 Nov 2023, at 17:50, Casey via groups.io <mbuilders@...> wrote:

?Thanks! Why do the jigs always have smaller holes through the bottom? I could see it making sense in a blind hole situation so the part would slide in and out without air compression/rarefaction, but why in a jig like that?

On 11/8/23 05:42, Nick Roast wrote:
This is the jig and heatsink we use for soldering 10 mm capsules. The loose piece is held in place with elastic bands to keep the capsules steady and in good thermal contact with the sink. We have been using lead free solder for many years, its not as shiny and can often look like a dry joint, but it has been problem free.
 

The hole also means the diaphragm can stay cooler than the rest of the capsule, in case the metal jig gets warm

On 8 Nov 2023, at 18:14, Casey via groups.io <mbuilders@...> wrote:

?Thanks -- but in the jig he posted it looks like you set the capsules in the slots and then put the enclosing piece in place, i.e. you're not pushing them into the hole? Maybe just to make it easier if you don't feel like taking the jig apart to swap out capsules?

On 11/8/23 10:08, jack wrote:
So the diaphragm isn¡¯t pressured when you insert the capsule into the hole
On 8 Nov 2023, at 17:50, Casey via groups.io <mbuilders@...> wrote:
?Thanks! Why do the jigs always have smaller holes through the bottom? I could see it making sense in a blind hole situation so the part would slide in and out without air compression/rarefaction, but why in a jig like that?

On 11/8/23 05:42, Nick Roast wrote:
This is the jig and heatsink we use for soldering 10 mm capsules. The loose piece is held in place with elastic bands to keep the capsules steady and in good thermal contact with the sink. We have been using lead free solder for many years, its not as shiny and can often look like a dry joint, but it has been problem free.
 

If you really want to remove heat then cover the mic holes with a little sticker and put some water between it and the heatsink. I suppose thermal pads would work just as well if they fit well in the jig. Hasn't someone measured mic drift from soldering before?

On the manufacturing side there are solutions to this problem - press-fit leadout pins, solder wires before swaging the capsule, extra vias in the PCB for press-fit connections, etc.

I guess another idea is to epoxy a leaf spring to a part of the microphone which will press on the pads and maintain contact, or press wires to the pads.
 

If you really want to remove heat then cover the mic holes with a little sticker and put some water between it and the heatsink.
_______________________________________

Gee ... um ... I would not chance doing that. I suspect water inside the capsule is contraindicated - and it would be easy to accomplish with capsules with rear air ventilation.

I do not always melt the pre-soldered pads. Instead, I use a low melting temperature solder to solder the lead wires atop or to the original solder pads. The new solder often activates the old solder so it becomes one gooey mess before cooling, and if not, the wires are soldered atop the original pads. Hope this makes sense. JHR
 

I want to add here that a little practice and being quick when you solder to the capsule and you will be fine. I have not damaged on and have soldered multiple capsules.

Do clean the pads with a bit of isopropyl first. Use a temp controlled soldering iron and good solder. I still use 63/37 Kester Eutectic.


Best Regards,

Jules Ryckebusch

On Nov 9, 2023, at 06:09, Richards <jrichards@...> wrote:

?If you really want to remove heat then cover the mic holes with a little sticker and put some water between it and the heatsink.
_______________________________________

Gee ... um ... I would not chance doing that. I suspect water inside the capsule is contraindicated - and it would be easy to accomplish with capsules with rear air ventilation.

I do not always melt the pre-soldered pads. Instead, I use a low melting temperature solder to solder the lead wires atop or to the original solder pads. The new solder often activates the old solder so it becomes one gooey mess before cooling, and if not, the wires are soldered atop the original pads. Hope this makes sense. JHR
 

I can second your recommendations, but I'm just wondering why you use IPA. Can you explain? It does not remove oxides, only organic contaminations. Flux would remove oxides and improve wetability, but you don't want to mess with that on your capsule. At least, I'd rather not use it on capsules. That's why I proposed in another message to scrape off the oxides before soldering. And maybe remove flux residues afterwards with IPA if I'm worried about long term moisture related effects.

OP also asked advice on solder wire thickness. This depends on the dimensions of the objects to solder. I always aim for 40-60% of the padwidth, both for solder wire thickness and solder tip width. The advantage of the thicker solder wire is that it contains more flux and will have better wetting properties.

Jan
 
Edited

You don't want to use thin solder wire as you will spend unnecessary time pushing it into the joint, adding extra heat. I usually use 0.6mm to 0.8mm rosin core. The Pinecil64 soldering iron has served me well and +- 1 degree C makes a meaningful difference. You want to be able to melt the solder fast, but not so fast the flux is spitting or smokes away instantly.

A soldering iron is several times hotter than the maximum temperature you want to reach the diaphragm. Even low melting solder is hot in comparison. A true eutectic 63/37 solder has a normal melting point, but melts and solidifies instantly with complete certainty. I can't overemphasize how important this is. Uncertainty is the main thing that leads to overheating. Not being able to tell whether the solder is melted, needs more flux, whether it's solid yet, whether it needs to be redone. With a good roll of 63/37 (and many of them do not have an accurate alloy mix), soldering is very quick and decisive. You don't need to hold the iron on for any longer than it takes for both surfaces to be "wetted". The pad does not have to be completely covered in solder, you just want to look at the edge of the solder blob and see that it is joined with the pad, rather than sitting on top like a bubble, and the moment you see that you remove the iron.
 

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Here is what I use. ?

image0.jpegimage1.jpeg
Best Regards,

Jules Ryckebusch?

On Nov 10, 2023, at 16:16, keantoken via groups.io <keantoken@...> wrote:

?

[Edited Message Follows]

You don't want to use thin solder wire as you will spend unnecessary time pushing it into the joint, adding extra heat. I usually use 0.6mm to 0.8mm rosin core. The Pinecil64 soldering iron has served me well and +- 1 degree C makes a meaningful difference. You want to be able to melt the solder fast, but not so fast the flux is spitting or smokes away instantly.

A soldering iron is several times hotter than the maximum temperature you want to reach the diaphragm. Even low melting solder is hot in comparison. A true eutectic 63/37 solder has a normal melting point, but melts and solidifies instantly with complete certainty. I can't overemphasize how important this is. Uncertainty is the main thing that leads to overheating. Not being able to tell whether the solder is melted, needs more flux, whether it's solid yet, whether it needs to be redone. With a good roll of 63/37 (and many of them do not have an accurate alloy mix), soldering is very quick and decisive. You don't need to hold the iron on for any longer than it takes for both surfaces to be "wetted". The pad does not have to be completely covered in solder, you just want to look at the edge of the solder blob and see that it is joined with the pad, rather than sitting on top like a bubble, and the moment you see that you remove the iron.

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