Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

SMTnet
»
Electronics Forum
»
Cleaning a PCB with a MEMS microphone on it

Cleaning a PCB with a MEMS microphone on it

Subscribe to Thread

Hey folks, I have a few designs that I'm using a MEMS I2S mi... - Oct 01, 2023 by Unexpected Maker

Can you install the part post-smt with no clean flux? ... - Oct 02, 2023 by dontfeedphils

I agree with dontfeedphils. Any time we run into a moisture ... - Oct 02, 2023 by Mainteneer

Thanks for the suggestion. Unfortunately, there are 2 issue... - Oct 02, 2023 by Unexpected Maker

Why ultrasonic cleaning? If the ultrasonics are causing prob... - Oct 03, 2023 by Stephen

Try a liquid latex masking material. Youll most likely have ... - Oct 03, 2023 by OptoGuillermo

I had the same thought. We use a peelable mask to protect co... - Oct 03, 2023 by Mainteneer

So, a couple of things... First, you're asking about water ... - Oct 05, 2023 by robgd3

Whatever the cleaning process is or will be, after cleaning ... - Oct 05, 2023 by MagyarT

First check the datasheet to see if it says do not Xray. I h... - Oct 05, 2023 by Stephen

I agree with everyone here that says microphones are meant f... - Oct 06, 2023 by chicagoindustrial

I don't know why you would NOT use a no clean paste. You're ... - Oct 07, 2023 by Tom

You can try expensive wash pallet that protects the part in ... - Oct 09, 2023 by Evtimov

Hey Rob, I am the designer and manufacturer of my own produ... - Oct 12, 2023 by Unexpected Maker

This is a very challenging situation indeed. Have you tried ... - Oct 12, 2023 by Mainteneer

Depending on the assemblies you're producing, I highly recom... - Nov 03, 2023 by calebcSMT

Unexpected Maker

#90015

Cleaning PCBs with a MEMS microphone on it | 1 October, 2023

Hey folks, I have a few designs that I'm using a MEMS I2S microphone on, and the PCBs have to be cleaned as I use water based SAC305 - but the supplier states to NOT ultrasonically clean their microphones.

Has anyone here been through the process of using and having to clean "un-cleanable" MEMS devices on their boards and found a solution?

Is it enough to cover the Mic hole with some kapton tape before cleaning (assuming the agitation doesn't make the tape come off) ?

Surely there must be a way to reduce damage to the parts when cleaning.

Changing to a no-clean paste is not an option, so I need to find a way to get these parts usable in my product/manufacturing requirements.

Thanks in advance!

Seon - Unexpected Maker

reply »

dontfeedphils

#90016

Cleaning PCBs with a MEMS microphone on it | 2 October, 2023

Can you install the part post-smt with no clean flux?

reply »

Mainteneer

#90021

Cleaning PCBs with a MEMS microphone on it | 2 October, 2023

I agree with dontfeedphils. Any time we run into a moisture sensitive component that cannot go through our wash cycle, we solder the component(s) by hand after everything that can be washed has been reflowed and cleaned.

reply »

Unexpected Maker

#90029

Cleaning PCBs with a MEMS microphone on it | 2 October, 2023

Thanks for the suggestion.

Unfortunately, there are 2 issues with adding them after: - The first is that doesn't scale to 1000's of board - The second is that half (or more) of the boards are double sided, complete PCB coverage on both sides and need to be cleaned after both sides are assembled, so I'd not be able to hot air or hot plate a Mic on after cleaning.

BTW, I tried kapton tape over the hole, but of course it came off during cleaning - doh - another dead microphone.

reply »

Stephen

#90030

Cleaning PCBs with a MEMS microphone on it | 3 October, 2023

Why ultrasonic cleaning? If the ultrasonics are causing problems then nothing will protect the mic. What about peelable mask?

reply »

OptoGuillermo

#90032

Cleaning PCBs with a MEMS microphone on it | 3 October, 2023

Try a liquid latex masking material. Youll most likely have to cover the hole with kapton, really drench the thing in the liquid latex to prevent the ultrasonic from damaging it then bake it at 50-70c for about 2-4 hours. With no bake its usually a 24hr dry time

reply »

Mainteneer

#90035

Cleaning PCBs with a MEMS microphone on it | 3 October, 2023

I had the same thought. We use a peelable mask to protect components during conformal coating. It could potentially give it complete protection with relatively easy removal.

reply »

robgd3

#90044

Cleaning PCBs with a MEMS microphone on it | 5 October, 2023

So, a couple of things...

First, you're asking about water washing a part, but, note that the manufacturer says to NOT ultrasonically clean their microphones. Those can be two different cleaning types...assembly shops using water wash may not be using ultrasonics in their cleaning process. Thus, you should check with the manufacturer specifically about water wash.

Second, I'm unsure if you are the designer, or the manufacturer/assembler (or both). If you are not the end manufacturing/assembly shop, I would suggest that you highlight this item as a cleaning-sensitive item to the assembly shop, and let them figure out the best method of assembling the device.

Third, why is no-clean not an option? There aren't a lot of reasons to restrict things from no-clean soldering. Some are high RF devices, for instance. However, if there are no functional reasons on the design that explicitly exempt the use of no-clean, why restrict it? Again, if you are not the manufacturer/assembler, I would suggest letting them manage their assembly process to provide the best product possible on delivery.

Cheers, ..rob

reply »

MagyarT

#90045

Cleaning PCBs with a MEMS microphone on it | 5 October, 2023

Whatever the cleaning process is or will be, after cleaning make sure you check on X-Ray for any solder balls/debris in microphones. This is a friendly reminder to check, unless you want to receive customer complaints. Been there, seen that - we went to change to no clean solder instead of scrapping hundreds of boards built up with microphones on + lots of customer complaints.

Best regards, Tom

reply »

Stephen

#90046

Cleaning PCBs with a MEMS microphone on it | 5 October, 2023

First check the datasheet to see if it says do not Xray. I have seen tiny microphones with a do not Xray warning.

reply »

chicagoindustrial

#90051

Cleaning PCBs with a MEMS microphone on it | 6 October, 2023

I agree with everyone here that says microphones are meant for no clean processes. Nothing will protect the device from an inline or batch wash. The mic should have been mounted on a different board if it must be washed. The one suggestion I have is consider asking someone like AGI Corp (Huntsville) to engineer a masking fixture with a gasket to protect just that IC (or more likely, area around the IC). It will be expensive. The other option is to manually deal with the fallout and know rework will be part of the process.

reply »

Tom

#90052

Cleaning PCBs with a MEMS microphone on it | 7 October, 2023

I don't know why you would NOT use a no clean paste. You're just adding time and cost to the assemblies, not to mention potential problems. Changing paste is the best option here unless you have a very compelling reason not to.

reply »

Evtimov

#90055

Cleaning PCBs with a MEMS microphone on it | 9 October, 2023

You can try expensive wash pallet that protects the part in question, or you can solder with NC solder after all wash is done.

reply »

Unexpected Maker

#90071

Cleaning PCBs with a MEMS microphone on it | 12 October, 2023

Hey Rob,

I am the designer and manufacturer of my own products - and I clean every product that leaves my premises because I hate receiving products with flux residue on them, so I wont ship products that way - It's my own standard I imposed on myself years ago, and I've never wavered. Yes, I'm my own worst enemy, but my products look spectacular.

My products are using facing - not hidden in boxes or cases - people hold my products in their hands and I want that experience to be exemplary.

The reason I don't use NC paste on my products is because if I do have to do any rework, I can't clean them without introducing typical NC residue from the cleaning process.

But it looks like I'm not going to be able to find a solution here to protect the Mic, and I can't place them after general cleaning, so I'm now researching low/no residue NC SAC305.

I'm hoping I can get the residue to non visible, and if I can, that's fine, but that still leaves me to options for rework without leaving a mess afterwards.

Cheers, Seon Unexpected Maker

reply »

Mainteneer

#90072

Cleaning PCBs with a MEMS microphone on it | 12 October, 2023

This is a very challenging situation indeed. Have you tried contacting the manufacturer of the component? I know of one time in the past we had a reflow issue and contacting the manufacturer actually proved insightful. I have seen claims using Diamond FN231 no clean solder paste gel that may be helpful to you here. Good luck finding a paste that performs in the way you need and sorry I couldn't provide more help!

reply »

calebcSMT

#90189

Cleaning PCBs with a MEMS microphone on it | 3 November, 2023

Depending on the assemblies you're producing, I highly recommend 8.9HF from Indium for a low residue SAC305 alloy. We have been using this for years in our NC process and residues are very little, with appropriate stencil apertures and paste printing.

reply »