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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Mike

#16602

Conformal Coating | 6 March, 1998

I will be starting a conformal coating process soon, I am looking for any pointers on 1) Best method for masking components, tape mask, liqued mask 2) Which is best Spray or Dip? 3) Compatiblity with no clean solder paste (flux residue) I have Miller Stephenson MS-472 (DIP), and Dow Cor 1-2577 Any feedback will be apreciated Mike

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Pat

#16606

Re: Conformal Coating | 6 March, 1998

Just recently tryed Miller Stephenson MS-465 spray, worked well. Also using Loctite 5290. The MS-465 air dried in about 15 min. The loctite requires ultra violet curing which took about 50 seconds, but didn't cure completely. The loctite will also moisture cure in a couple of hours. I would recommned the MS-465 Both have a very wet consistency and are not recommended for a automated line. Loctite makes a thicker coating if you want to use a dispenser and a UV tunnel. | Any feedback will be apreciated | Mike

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Scott McKee

#16605

Re: Conformal Coating | 6 March, 1998

| I will be starting a conformal coating process soon, I am looking for any pointers on | 1) Best method for masking components, tape mask, liqued mask Masking tape or rubber caps will work, the ligued mask is too hard to remove. | 2) Which is best Spray or Dip? Depends on the application and if sealing is required under devices. Is your application Military or Commercial? | 3) Compatiblity with no clean solder paste (flux residue) I haven't heard the jury on this yet - but a cleanliness test will be required to insure that the board is clean. | I have Miller Stephenson MS-472 (DIP), and Dow Cor 1-2577 I'm not familiar with these two chemicals, what kind are you looking at - urithane? What's your coating supplier suggest? Need to monitor Humidity and Temperature for proper curring. | Any feedback will be apreciated Hope this hels, Scott McKee | Mike

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Mick Jones

#16604

Re: Conformal Coating | 20 March, 1998

| I will be starting a conformal coating process soon, I am looking for any pointers on | 1) Best method for masking components, tape mask, liqued mask | 2) Which is best Spray or Dip? | 3) Compatiblity with no clean solder paste (flux residue) | I have Miller Stephenson MS-472 (DIP), and Dow Cor 1-2577 | Any feedback will be apreciated | Mike We are a UK company who has been conformally coating for the past 9 years using an Acrylic material called Humiseal 1B31. This material has full MIL spec, and has also been SIR tested by us over no-clean fluxes with no problems. We have actually been supplying our products with this coating over no-clean fluxes for the last 5 years. We have now transferred production from a Dipping process to a spraying process, with 3 Nordson Selectcoat machines and Vitronics curing ovens. I can recommend both Nordson and Vitronics, but there are very few alternatives to Nordson in the UK anyway! All of our products are certified by FM, CSA, BASEEFA, and various other bodies, and none of them specify that we must dip. Their only stipulation is that we apply two coats with a cure inbetween. The curing ovens should be 100% I.R., convection is not recommended as you will get skinning and bubbling. Our oven profile basically gives a slow ramp up (to avoid skinning) to a max board temperature of 90�C. The total time in the oven is @10 minutes. Please feel free to email me if you think I can help any further.

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Sam Forman, MicroCoat Technologies

#16603

Re: Conformal Coating | 4 April, 1998

| I will be starting a conformal coating process soon, I am looking for any pointers on | 1) Best method for masking components, tape mask, liqued mask | 2) Which is best Spray or Dip? | 3) Compatiblity with no clean solder paste (flux residue) | I have Miller Stephenson MS-472 (DIP), and Dow Cor 1-2577 | Any feedback will be apreciated | Mike Mike: Most commonly used process is spraying UV cure acrylic or epoxies for protection. Stay away from solvent based products. A peelable solder mask is used over gold fingers, holes, etc. Let me know what your requirements are.

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