Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Aqueous Cleaning

#10353

Aqueous Cleaning | 30 July, 1999

Very shortly I will be evaluating OA flux and aqueous cleaning to replace our RMA and solvent cleaning process. I am primarily interested in batch aqueous cleaners for reasons of budget, floor space, etc. I am concerned about the ability of H2O to clean under low standoff components like TSOPs. Will a saponifier be necessary to help break the surface tension of the H2O (are saponifiers even compatible with OA fluxes)? I am hoping to be able to clean with just DI water. Your experiences with batch cleaners is much appreciated.

Thanks,

Bob

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#10354

Re: Aqueous Cleaning | 30 July, 1999

| Very shortly I will be evaluating OA flux and aqueous cleaning to replace our RMA and solvent cleaning process. I am primarily interested in batch aqueous cleaners for reasons of budget, floor space, etc. I am concerned about the ability of H2O to clean under low standoff components like TSOPs. Will a saponifier be necessary to help break the surface tension of the H2O (are saponifiers even compatible with OA fluxes)? I am hoping to be able to clean with just DI water. Your experiences with batch cleaners is much appreciated. | | Thanks, | | Bob | Some people say batch cleaners can't consistently clean fine pitch devices. Some contractors are using batch cleaners instead of in-line cleaners. But ya know Bob, you should solder some components on a board, clean it with different batch cleaners, pull the components, and measure the flux residues where the component was located. Alternately you could put some combs under the components and measure the SIR.

My2�

Dave F

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#10355

Re: Aqueous Cleaning | 30 July, 1999

It is true that the use of saponifiers (and other water soluble additives) will lower the surface tension and aid in under component penetration. It is also true, however, that other specific design features within a batch machine can also aid in under component penetration without the use of such chemical additives.

We have manufactured hundreds of batch machines. More than 50% of them are in use in OA flux / paste removal from fine-pitch, high-density SMT applications without the use of a chemical additive. The rest of them are cleaning no-clean and RMA, both of which require a chemical additive. I have seen some isolated cases, however, where a chemical additive is needed but these cases are quite rare.

My recommendation would be to try not to use any chemical additives if possible. The absence of chemicals provides the ability to close-loop the entire cleaning process very economically (not to mention lowering the cost of cleaning).

I would also recommend that you send samples of your boards (with plenty of flux under the components) to the equipment manufacturers to verify the acceptability of a chemical-free process.

Good Luck,

Mike Konrad

| | Very shortly I will be evaluating OA flux and aqueous cleaning to replace our RMA and solvent cleaning process. I am primarily interested in batch aqueous cleaners for reasons of budget, floor space, etc. I am concerned about the ability of H2O to clean under low standoff components like TSOPs. Will a saponifier be necessary to help break the surface tension of the H2O (are saponifiers even compatible with OA fluxes)? I am hoping to be able to clean with just DI water. Your experiences with batch cleaners is much appreciated. | | | | Thanks, | | | | Bob | | | Some people say batch cleaners can't consistently clean fine pitch devices. Some contractors are using batch cleaners instead of in-line cleaners. But ya know Bob, you should solder some components on a board, clean it with different batch cleaners, pull the components, and measure the flux residues where the component was located. Alternately you could put some combs under the components and measure the SIR. | | My2� | | Dave F |

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Graham Naisbitt

#10356

Re: Aqueous Cleaning | 2 August, 1999

| Very shortly I will be evaluating OA flux and aqueous cleaning to replace our RMA and solvent cleaning process. I am primarily interested in batch aqueous cleaners for reasons of budget, floor space, etc. I am concerned about the ability of H2O to clean under low standoff components like TSOPs. Will a saponifier be necessary to help break the surface tension of the H2O (are saponifiers even compatible with OA fluxes)? I am hoping to be able to clean with just DI water. Your experiences with batch cleaners is much appreciated. | | Thanks, | | Bob | Bob,

I will go further than Dave F (hello Dave) You need to determine the operating conditions your assembly will see and then test the finished product accordingly - refer to J-STD001B and IPC-TM-650 for guidance.

You MAY find that you can run no-clean. On the other hand, you MAY find that you have to invest over $100K in a cleaner - you have to decide the relative value of your product and the cost implications if it fails warranty - if that means a nuclear missile goes astray - I'll sue YA even if no-one else does!

Hope this gets to you before its too late.

Regards, Graham

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