I suppose Me 3 is a bit funky? But I got it also... 😊
Scott Decker
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-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of [log in to unmask]
Sent: Wednesday, March 20, 2024 08:27
To: [log in to unmask]
Subject: [External] Re: [TN] Surface energy for conformal coating
Me too, Steve.
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Ioan Tempea
Sent: Wednesday, March 20, 2024 8:50 AM
To: [log in to unmask]
Subject: Re: [TN] Surface energy for conformal coating
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I got it Steve.
Ioan
De : Steve Gregory <[log in to unmask]>
Envoyé : March 20, 2024 8:49 AM
À : TechNet E-Mail Forum <[log in to unmask]>; Ioan Tempea <[log in to unmask]> Objet : Re: [TN] Surface energy for conformal coating
Hi all,
So I've seen Doug's reply and Ioan's reply. I'm going to reply and see if anybody gets this...
Steve
On Wed, Mar 20, 2024 at 6:34?AM Ioan Tempea <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Thanks Doug,
Can't get it more thorough than that!
We do have a Surface Analyst so I guess I'll request a side by side dyne/contact angle characterization, to get the angle equivalents of 40+ dynes.
Best regards,
Ioan
-----Message d'origine-----
De : TechNet <[log in to unmask]<mailto:[log in to unmask]>> De la part de Pauls, Doug O Collins Envoyé : March 20, 2024 8:18 AM À : [log in to unmask]<mailto:[log in to unmask]>
Objet : Re: [TN] Surface energy for conformal coating
You're welcome.
Indiscrete Answers
- We will typically take surface energy readings when we qualify a new board site, then monitor a few incoming lots, but often we do not test again unless we have reason to go looking. The dyne pens, while inexpensive and easy to use, are variable in interpretation. A more accurate and repeatable measurement can be made with instruments designed to measure surface tension and surface energy. There is one by Kruss, out of Switzerland, and one from Brighton Science (formerly BTG Labs) (Surface Analyst). We have both. Both work.
- Yes, manufacturing processes can impact surface energy. When we qualify a site, we have a qualification vehicle fabricated by the candidate site that then goes through our manufacturing processes. Then we measure surface energy to see how much the manufacturing process impacted the surface. We have some very robust cleaning processes, so we seldom see the surface energy go down if the solder mask was fully cured to start with.
Douglas Pauls | Sr. Technical Fellow | Electronics AMT COLLINS AEROSPACE
400 Collins Road NE, MS 108-101, Cedar Rapids, IA 52498 USA
Tel: +1 319 295 2109 | Mobile: +1 319 431 3773
-----Original Message-----
From: TechNet <[log in to unmask]<mailto:[log in to unmask]>> On Behalf Of Ioan Tempea
Sent: Wednesday, March 13, 2024 6:11 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [External] Re: [TN] Surface energy for conformal coating
Thanks Doug!
Indiscreet questions:
- How do you make sure your spec is what you get? Do you request dyne testing by the PCB fab?
- Do you measure dynes at Incoming or just in case you have issues on the assembly line?
- Does surface energy variate during assembly? I mean a 40+ dynes/cm at Incoming, will it stay the same after 2 reflows, some TH assembly, rework, staking, etc., even with proper cleaning?
Best regards,
Ioan
-----Message d'origine-----
De : TechNet <[log in to unmask]<mailto:[log in to unmask]>> De la part de Pauls, Doug Collins Envoyé : March 12, 2024 10:03 PM À : [log in to unmask]<mailto:[log in to unmask]> Objet : Re: [TN] Surface energy for conformal coating
Ioan,
In general, I have used this rule of thumb:
<30 dynes/cm - you will see problems with adhesion and wetting.
30-35 dynes/cm - you will still see problems with adhesion and wetting, but not as much as under 30.
35-40 dynes/cm - generally decent adhesion and wetting but occasional issues
40+ dynes/cm - good adhesion and wetting. Collins specifies >44 dynes/cm for its solder mask.
Douglas Pauls | Sr. Technical Fellow | Electronics AMT COLLINS AEROSPACE
400 Collins Road NE, MS 108-101, Cedar Rapids, IA 52498 USA
Tel: +1 319 295 2109 | Mobile: +1 319 431 3773
-----Original Message-----
From: TechNet <[log in to unmask]<mailto:[log in to unmask]>> On Behalf Of Ioan Tempea
Sent: Monday, March 11, 2024 2:42 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [External] [TN] Surface energy for conformal coating
Hello Technos,
Some many years ago I have discovered, with help from this illustrious panel, the existence of the dyne pens. Have used them for a while and them moved to microelectronics, where I have spent 11 years without any contact with conformal coating. So I've kinda forgot some details.
Where I work we have the Surface Analyst device, measuring contact angles and this is supposed to obsolete the use of dyne pens.
The trouble is I can't remember what dyne values are related to good coating wetting. Or even better, which contact angles are preferred?
Can anyone help?
I'm interested in both solder masked PCBs and Au plated ceramics and the optimal values I believe differ from PCB to ceramics.
Also, do you have any good articles or textbooks to recommend on this matter?
Thanks,
Ioan
--
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133
Cell Phone: (918) 706-2779
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