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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Cleaning Water Soluble Flux under BGA's

Dreamsniper

#27716

Cleaning Water Soluble Flux under BGA's | 23 March, 2004

First Time to solder BGA's using Water Soluble. We are currently using an Aquaeous Cleaner to clean our PCB's but I find it not enough to clean the flux from under our BGA's. Has anyone had this experience before that he may like to share how he manage the problem? I really need help and would be very glad to thank you guys in advance in helping me to overcome this issue.

Ta. Dreamy

reply »

#27726

Cleaning Water Soluble Flux under BGA's | 24 March, 2004

I think you can effectively clean under any other low standoff device. It's an issue of surface tension, pressure, and flow rate. DI water is the starting point, but the surface tension of straight DI water makes it difficult to get under low standoff parts. A saponifier with a good surfactant package can reduce the surface tension problems of the DI water and allow the cleaning solvent to move under low-standoff parts. Then, it becomes an issue of how quickly and much fluid can be delivered. Further, some cleaning agents work for low standoff devices without damaging the materials.

reply »

Dreamsniper

#27733

Cleaning Water Soluble Flux under BGA's | 24 March, 2004

Hi Dave,

Can you elaborate more on the Saponifier system process and the surface tension during aquaeous cleaning?

thanks and regards,

reply »

#27736

Cleaning Water Soluble Flux under BGA's | 24 March, 2004

Dreamy

It sounds like you are having fun in your new job.

Saponifier. Alkaline chemicals, added to water, that convert rosin/resin flux residues in the water to soluble soaps.

Generally, saponifiers are better if used in an aggressive spray-in-air system. Low agitation immersion systems (heated baths or refurbished vapor degreasers) are not compatible with saponifiers. Saponifiers need a high degree of mechanical energy to force the flux-to-soap conversion.

Saponifiers work well in in-line aqueous cleaners and batch aqueous cleaners. There are a number of saponifiers available. Some are: 3 Saponifier / non saponifier saponifier 3a Saponifiers: * Aqueous Technologies: PCB-Wash http://www.aqueoustech.com * Kyzen: XJN http://www.kyzen.com * EnviroSense: Enviro Gold #816 http://www.envirosense-inc.com 3b Non-Saponifiers saponifier: * Zestron: A200 http://www.zestron.com * Petroferm: Hydrex http://www.petroferm.com

Over the years, Mike Konrad and other SMTneters have written thoughful discourses on saponifiers. Search for them in the SMTnet Archives. [Maybe someone can rouse Mike from his nap, so that he can do a better job of explaining this than I.]

reply »

Jemal khaiar

#27737

Cleaning Water Soluble Flux under BGA's | 25 March, 2004

Mike Konrad

#27743

Cleaning Water Soluble Flux under BGA's | 25 March, 2004

OK� Nap time�s over!

Technically speaking, water soluble flux is just that, soluble in water. Technically speaking, one does not need a saponifier or any other chemical agent to remove water soluble (OA) flux residues.

However, one must consider the following factor: Water must get to the flux. If the flux is under a very low stand-off component, water may not be able to contact the flux. The cleaning agent (water) must have vigorous contact with the flux in order to remove it.

In tightly spaced applications such as BGA�s, Flip-Chip, etc, a chemical additive is helpful to lower the wash solution�s surface tension, allowing adequate contact with the flux residues.

Most wash systems place all of their effort on the wash cycle. After all, you are cleaning the boards primarily to remove flux residues. As a chemical additive is normally required for low stand-off components, regardless of flux type, one should give greater consideration to the rinse cycle.

With the right chemical, the correctly sized wash pump, strategically placed nozzles producing the right spray pattern, one will solubilize the flux. But what about the wash chemical? The rinse process removes the wash chemical and displaces it with high quality DI water. The only thing worse than leaving flux on a board is leaving cleaning chemicals on a board. It is imperative that the wash chemical be thoroughly removed. Failure to remove the wash chemical will normally result in board failures.

If you choose to include a wash chemical in your cleaning process, be sure that your cleaning system has a robust rinse ability. In reality, the rinse section of your cleaning system should actually be more powerful than your wash system. Rinsing is the most critical of the Wash, Rinse, Dry processes.

As for acceptable chemicals are concerned, our friend Dave�s list is spot-on. For water soluble applications, the chemical requirement is not as precise as in no-clean and RMA applications. Almost any chemical additive will do the trick. You will be able to cut the recommended chemical percentage in half compared to other applications. Another advantage of using a chemical additive is the neutralizing effect a high pH chemical has on an acid-based OA flux. The chemical will also remove other �environmental� contaminants such as human hand oils, and other contaminants picked up through your assembly process.

I hope this helps!

Mike Konrad Aqueous Technologies (909) 944-7771 ext 29 www.aqueoustech.com konrad@aqueoustech.com

reply »

#27747

Cleaning Water Soluble Flux under BGA's | 25 March, 2004

Thank you Mike. What is your thinking on the use of surficants, as an alternative to saponifiers, for cleaning under low standoff parts?

Dreamy: Adding another point to the low standoff part conversation: If you have cleaning issues with 1.27 BGA, let's not start thinking about what's going on under your fine pitch QFP.

Jemal: Tks

reply »

Mike Konrad

#27748

Cleaning Water Soluble Flux under BGA's | 25 March, 2004

A surfactant (AKA detergent) is great for OA flux removal applications. It has a good surface tension reducing property and is more easily rinsed than soaps. If using a soap or surfactant, be sure that you choose one that has a good de-foaming package. The last thing you need is a foam monster creeping out of the washer�s door!

Mike Konrad Aqueous Technologies (909) 944-7771 ext 29 www.aqueoustech.com konrad@aqueoustech.com

reply »

Dreamsniper

#27749

Cleaning Water Soluble Flux under BGA's | 25 March, 2004

Oh Wow! Thanks a lot guys...I learned a lot from your good and spot on knowledge. You guys are really very helpful.

Thanks

Dreamy

reply »

PCB Soldering Tools

PCB Cleaning