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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Steve Cheung

#9755

Cleaning of 'No-Clean' paste | 7 September, 1999

We are changing over to a No-Clean paste soon and l was wondering how other people tackle the issue of stencil and PCB cleaning in high-volume production.

The paste we are using is Cobar 325RX and its pretty sticky stuff let me tell you!

Our problem is that we may have up to 6 stencils and over 50 pcbs that will require cleaning every hour. Cleanliness is crucial from a quality standpoint so manual cleaning is not a preferred option.

Ultrasonics are fine for semi-aqueous pastes but are limited for No-Clean. 'Safewash' is the best wash solution we have found to date.

Any suggestions guys??

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Earl Moon

#9756

Re: Cleaning of 'No-Clean' paste | 7 September, 1999

| We are changing over to a No-Clean paste soon and l was wondering how other people tackle the issue of stencil and PCB cleaning in high-volume production. | | The paste we are using is Cobar 325RX and its pretty sticky stuff let me tell you! | | Our problem is that we may have up to 6 stencils and over 50 pcbs that will require cleaning every hour. Cleanliness is crucial from a quality standpoint so manual cleaning is not a preferred option. | | Ultrasonics are fine for semi-aqueous pastes but are limited for No-Clean. 'Safewash' is the best wash solution we have found to date. | | Any suggestions guys?? | Here, and and on my last contract site, we use ultrasonics for stencil cleaning with good results using SMQ92 pastes. Board cleaning remains something of an issue everywhere I go, as is evidenced by past and current postings, and the question arises concerning how clean is clean?

Currently, we are sparing not expense to get "acceptable" board cleaning results. The equipment and experiment costs soar as do some problems.

Wish I could help more, but there seems to be as many questions as answers. Even our visiting Phd chemical types are without all the answers, or are hiding their "secret" formulations - as usual.

Earl Moon

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#9757

Re: Cleaning of 'No-Clean' paste | 7 September, 1999

You are correct in your assessment that no-clean pastes are difficult to clean.

I understand why you would need to clean lots of stencils, but why would you need to clean "high volumes" of PCB's? If you are planning on cleaning high volumes of PCB's, then why don't you use a paste designed to be cleaned?� Just curious.

Your assessment that ultrasonics may not be good for no-clean pastes is not accurate. Most of our customers use our ultrasonic stencil cleaner for no-clean paste. There are some no-clean applications, however that are more difficult than others.

The best combination that I've seen is an ultrasonic cleaner with Zestron's SC200 chemistry. The chemistry is safe, low temperature, lasts for more than one year (if your stencil cleaner has wash-solution filtration) and is compatible with many brands of stencil cleaners, both spray-in-air (which I do not recommend) spray under immersion, and ultrasonic.

The stencil cleaners that I know will work on your application are:

Aqueous Technologies (ultrasonic): (800) 218-8128 (that's us) PMR (ultrasonic): (602) 829-8170 Branson (ultrasonic): (203) 796-0400 EMC (spray-in-air): (215) 340-0650 Speedline / Electrovert (spray-under-immersion): (972) 606-1900

Good Chemistries: Zestron: (703) 589-1198 Kyzen: (800) 845-5524 Petroferm: (904) 261-8286

I hope this helps.

Mike Konrad

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armin

#9758

Re: Cleaning of 'No-Clean' paste | 7 September, 1999

| | We are changing over to a No-Clean paste soon and l was wondering how other people tackle the issue of stencil and PCB cleaning in high-volume production. | | | | The paste we are using is Cobar 325RX and its pretty sticky stuff let me tell you! | | | | Our problem is that we may have up to 6 stencils and over 50 pcbs that will require cleaning every hour. Cleanliness is crucial from a quality standpoint so manual cleaning is not a preferred option. | | | | Ultrasonics are fine for semi-aqueous pastes but are limited for No-Clean. 'Safewash' is the best wash solution we have found to date. | | | | Any suggestions guys?? | | | Here, and and on my last contract site, we use ultrasonics for stencil cleaning with good results using SMQ92 pastes. Board cleaning remains something of an issue everywhere I go, as is evidenced by past and current postings, and the question arises concerning how clean is clean? | | Currently, we are sparing not expense to get "acceptable" board cleaning results. The equipment and experiment costs soar as do some problems. | | Wish I could help more, but there seems to be as many questions as answers. Even our visiting Phd chemical types are without all the answers, or are hiding their "secret" formulations - as usual. | | Earl Moon |

We used to clean volumes of pcb's using an aqeous cleaner and we find it acceptable.

regards, dreamsniper

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#9759

Re: Cleaning of 'No-Clean' paste | 13 September, 1999

Mike failed to list the company that introduced the first ultrasonic stencil cleaner in 1990. The company remains the leader in stencil cleaning worldwide:

Smart Sonic Corporation Tel: 1(800)906-4407 Fax: 1(818) 909-6409 e-mail: smt@smatrsonic.com web site: www.smartsonic.com

However, your assumption that "ultrasonics" is the answer is only half correct. The most important part of any cleaning process is the chemistry. Smart Sonic only uses ultrasonic technology because it will deliver their chemistry (440-R SMT Detergent) into fine-pitch apertures where spray jets cannot penitrate.

The original "rosin based" no-clean solder pastes are easier to clean than the newer "hybrid" no-cleans. Some solder paste mfgrs. use parafins and other binders to help improve the printability of their solder paste. Unfortunately, these additives sometimes make the paste more difficult to clean.

If you are concerned about your particular solder paste, Smart Sonic will test clean it for at no charge.

| You are correct in your assessment that no-clean pastes are difficult to clean. | | I understand why you would need to clean lots of stencils, but why would you need to clean "high volumes" of PCB's? If you are planning on cleaning high volumes of PCB's, then why don't you use a paste designed to be cleaned?� Just curious. | | Your assessment that ultrasonics may not be good for no-clean pastes is not accurate. Most of our customers use our ultrasonic stencil cleaner for no-clean paste. There are some no-clean applications, however that are more difficult than others. | | The best combination that I've seen is an ultrasonic cleaner with Zestron's SC200 chemistry. The chemistry is safe, low temperature, lasts for more than one year (if your stencil cleaner has wash-solution filtration) and is compatible with many brands of stencil cleaners, both spray-in-air (which I do not recommend) spray under immersion, and ultrasonic. | | The stencil cleaners that I know will work on your application are: | | Aqueous Technologies (ultrasonic): (800) 218-8128 (that's us) | PMR (ultrasonic): (602) 829-8170 | Branson (ultrasonic): (203) 796-0400 | EMC (spray-in-air): (215) 340-0650 | Speedline / Electrovert (spray-under-immersion): (972) 606-1900 | | Good Chemistries: | Zestron: (703) 589-1198 | Kyzen: (800) 845-5524 | Petroferm: (904) 261-8286 | | I hope this helps. | | Mike Konrad | |

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