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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


CSP No clean residue

Scott B

#31575

CSP No clean residue | 6 December, 2004

We are currently reviewing a design which has a leadless chip scale package with a solder thermal pad on the underside. The application notes for the device specify use of a no-clean solder paste as the gap under the device will prevent cleaning.

Is there any data relating to the long term (15-20 years) reliability implications of no-clean residues.

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#31590

CSP No clean residue | 7 December, 2004

We'd suggest listening to your CSP component supplier. The standoff is too low. Check with your flux suppliers for the information you seek.

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#31596

CSP No clean residue | 8 December, 2004

Hello I thind you are same Mr. Scott from whom once i had purchased inspection system in M/s Evershine India.

Regarding your query, we want to inform you that we are mounting BGA with water solubel flux (special flux paste) from alpha metals and then we are cleaning it by De ionised water. You can use the no clean flux paste for same but several manufacturer has claimed that the life is bit less as compared to water solubel process.

Regards

KS

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Scott B

#31599

CSP No clean residue | 8 December, 2004

Have been trying to cut through Paste supplier 'Qualification' documents and sales blurb but when asked if they'd put their mortgages on the line, assurances are harder to come by. In God we trust - All others must provide data.

Are there any previous independant studies that you aware of that address this long term / harsh environment requirement.

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#31603

CSP No clean residue | 8 December, 2004

If you email me your email address, I'll send you a contact that may be able to help.

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#31604

CSP No clean residue | 8 December, 2004

KS: You're correct. The standoff on a 1.00mm and 1.25mm BGA is high enough to allow cleaning. The standoff on 0.8mm BGA does not allow proper cleaning, even with saponifiers.

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#31695

CSP No clean residue | 13 December, 2004

Hi Scott - No clean assemblies have a very low tolerance for processing residues, and long term reliability is compromised if residues from incoming bare boards, components, or un-solublized flux residues are not dealt with. It is critical to control these aspects of cleanliness since a no clean process is not meant to go through cleaning, and cleaning is very difficult if a residue is discovered after assembly. To see some studies on this topic, visit our website at http://www.residues.com and look under our resources section. If you have more specific or detailed questions, feel free to contact our company offline through the info on our website.

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#31830

CSP No clean residue | 23 December, 2004

The Jury is still out on no-clean reliability in the long term as no-clean didn't gain wide spread acceptance until the early 1990's. Also, in today's disposable society, few products are expected to last 15-20 years.

Experience has shown that if your product has one or more of the following attributes, you may want to do some accelerated life testing: 1. Marginally solderable surfaces 2. High impedence circuits 3. Service or environmental temperatures exceeding 50 C 4. Humidity exceeding 85% during operation, 95% storage. 5. Hand soldering is used to assemble rework

Lastly, you can effectively clean these gaps with the correct solvent delivered at the right temperature & pressure. When in doubt, Clean.

Steve Stach Austin American Technology www.aat-corp.com (+1) 512-335-6400

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Sandy Kelley

#33206

CSP/BGA Applications | 15 March, 2005

I have been engaged to find an Applications Engineer for an electronic materials division of a worldwide multi-billion dollar diversified international specialty chemical endeavor. My client is a well respected, cutting edge technology leader in underfill chip scale packaging electronic materials for uses in cell phone, wireless applications and more.

They are in need of a particular combination of experience in process engineering, CSP equipment knowledge and materials understanding to help compnaies like Amkor, Intel, Motorola or Nokia to apply pre-applied underfill in the flip chip or BGA assembly process.

Unlike their close competition, they have materials that are proven to work. Referrals are appreciated.

Thanks and regards,

Sandy Kelley, emhunter@erols.com

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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Sandy Kelley

#33207

CSP No clean residue | 15 March, 2005

I have been engaged to find an Applications Engineer for an electronic materials division of a worldwide multi-billion dollar diversified international specialty chemical endeavor. My client is a well respected, cutting edge technology leader in underfill chip scale packaging electronic materials for uses in cell phone, wireless applications and more.

They are in need of a particular combination of experience in process engineering, CSP equipment knowledge and materials understanding to help compnaies like Amkor, Intel, Motorola or Nokia to apply pre-applied underfill in the flip chip or BGA assembly process.

Unlike their close competition, they have materials that are proven to work. Referrals are appreciated.

Thanks and regards,

Sandy Kelley, emhunter@erols.com

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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#33212

CSP/BGA Applications | 15 March, 2005

There is equipment available to clean NC residues off low standoff devices, well below 0.8mm (0.031"), from Speedline Technologies- Electrovert and Accel. See this paper under Accel:

"High Reliability Underfill Performance through Proper Flip-Chip Die Attach Defluxing"

http://www.speedlinetech.com/news_publications/white-papers.aspx#Accel

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KEN

#33221

CSP/BGA Applications | 15 March, 2005

Why in Gods name would you use no-clean and then clean it?

....I guess I just don't get it.

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ams

#33222

CSP/BGA Applications | 16 March, 2005

What is the joint stand-off gap anticipated after the board level assembly and reflow? If it is designed per CSP standards, there should be no issue in water cleaning. If the gap is 90 � 100 micron, better to go with a no clean paste. His needs good process controls.

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ams

#33223

CSP No clean residue | 16 March, 2005

KS, Can you contact me for some business opportunities? e-mail me at goburam@yahoo.com AMS

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Bob R.

#33226

CSP/BGA Applications | 16 March, 2005

I won't speak for the person asking the original question, but one reason I can think of is in a high reliability application where the CSP needs underfilled and, depending on the underfill, cleaning may be necessary for underfill adhesion. Why use a no-clean solder in that situation? Because other products using that line may not need cleaned so you may not want to introduce an additional paste to the line and chance a mix up.

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