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Date: November 03, 2009 09:32 AM
Author: CooLepse
Subject: Gluing Quality Issue !!!

Hi all,

I'm today looking for adhesive specifications on SMT process (by printing).

The Glue printing process is new in my company, and I need info, please!!!

Do you know specifications about Shear component value with gluing process (on component type 1206, 0805, 0603...)?

How can we improve shear values on a glue printing Process ???

Hope you'll be able to help me.

Best regards.

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60280)

Date: November 03, 2009 11:46 AM
Author: davef
Subject: Gluing Quality Issue !!!

Search the finee SMTnet Archives for previous posts on the topic. Here's a clip from on of those posts that may get you started.
[snip]
* Stencil material: metal or plastic, no difference in print, metal is easier to clean, no static problem, available
* Stencil thickness: Chips 0.006", SOIC 0.010" [print height equals 1/3 thickness]
* For 0603, aperture size was an oblong shape , 0.030" long x 0.015" wide. A minimum of 0.010" gap between the aperture and pad, both sides.
* Snapoff: to increase dot height, upto 0.040" can be used
* Squeegee material: metal on metal, polycarbonate on plastic
* Print speed: 1 to 2" per sec
* Squeegee pressure: 0.2 to 0.3 kg/cm ... enough to clean wipe the stencil
* Separation speed: Slow ... 0.1 to 0.5 mm/sec over 3mm separation distance
* Print sequence: print print

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60282)

Date: November 04, 2009 03:33 AM
Author: CooLepse
Subject: Gluing Quality Issue !!!

Hi Davef,

I have already checked the SMTnet archives but unfortunetly I didn't find answers regarding mechanical behviour specifications of component glued on substrat.

This king of soldering process is new for us.

For example, the specification for component soldered by paste is about 0,5kg/mm².

But what about the glue ???

Can you give some info ??? Quality speeking ?

Thanks in advance.

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60295)

Date: November 04, 2009 06:47 AM
Author: davef
Subject: Gluing Quality Issue !!!

There may be supplier guidelines or accepted practice, but there is no shear specification for printing either paste or glue.

Beyond the issue of not knowing the shear value, what's the problem that you see when printing glue?

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60297)

Date: November 04, 2009 08:41 AM
Author: rajeshwara
Subject: Gluing Quality Issue !!!

For 1206 SHEAR VALUE REQUIRED IS 30 TO 70 gmfcm.
please tell me which glue u are using and upload the datasheet if u have or mail it to me at smtschool@gmail.com

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60301)

Date: November 05, 2009 03:40 AM
Author: CooLepse
Subject: Gluing Quality Issue !!!

Hi Rajeshmara,

Mail sent with the datasheet of the glue we use in production.

Thanks for first information you provide me for the shear specifications on 1206. But can you be more precise on this point ? How did you define it ?

Is anyone have more information about mechanical properties of the glue on components ? (Shear test...)

Please note that I'm here talking about Electrically Conductive Adhesive for solder replacement !

What are the main parameters we have to check on the printing process in order to improve the maintain of components after gluing on the substrat?

(Thickness, area ?)

Hope you'll be able to help me !

Thanks in advance.

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60322)

Date: November 05, 2009 04:56 PM
Author: Lynn Norman
Subject: Gluing Quality Issue !!!

In a previous job, we had torque off requirements for different sized components for our screen print adhesive (non-conductive in our case). We used a torque watch that would measure max torque, so we could test production boards, shear testing was impractical. The values were determined before my time, but I think we worked with the adhesive manufacturer.

Like was said before, there is no spec on shear or torque strength, because there are too many variables to cover all circumstances (component metallization, board metallization, solder composition, etc.). Not much help I know, but torque off strength was a property that could be measured quickly and easily, just another option.

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60338)

Date: November 12, 2009 12:05 PM
Author: CooLepse
Subject: Gluing Quality Issue !!!

Up!

Thanks anyway for your answer Lynn.

But I'm still in the issue regarding the assembly of passive components on substrat with conductive adhesive.

We hardly reach the minimum specifications of shear strengh for each component we use (1206, 0805 and 0603).

So we are today not able to validate the process...

Any help will be usefull !!!

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60427)

Date: November 13, 2009 04:45 AM
Author: Loco
Subject: Gluing Quality Issue !!!

Hi dave,

Sorry to hi-jack the tread a bit, but,we are experiencing some problems with components falling off somewhere in our factory, you made me think about printer settings being an issue.

By print print, do you mean a double sweep of the squeegees, let them move to the front and to the back?

Could you refer me to other posts with these kind of recommended settings?

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60431)

Date: November 13, 2009 07:03 AM
Author: davef
Subject: Gluing Quality Issue !!!

Loco

[snip]
"The print mode is another consideration. Printers are designed with a squeegee bar and a flood bar. In flood mode the flood bar spreads the paste, and in print mode the squeegee applies pressure, such that the actual printing takes place. When the flood bar is spreading the paste, the squeegee is up [riding] and when the squeegee is printing, the flood bar is up [riding]. Since the two bars are identical, if the design allows, their functions can alternate. Some equipment can perform only in the flood/print mode, and others offer both print/print and flood/print modes. Some of the older machines are not suitable for stencil application, because they are not flexible and cannot provide the print/print mode.
Only the print/print mode can be used with stencils, because the holes are completely open and it is necessary to prevent the paste from oozing out of the holes and dripping onto the substrate surface. For screens, the flood/print mode is used. Naturally, equipment is more desirable if it can function in various modes and can be used for both stencils and screens." [Surface mount technology: principles and practice, RP Prasad, Springer, 2nd edition, 1997]
[snip]

That aside, your issue probably has nothing to do with printing. Here's a link to one of the threads on the topic from the fine SMTnet Archives that's closer to the solution; http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=23422

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60434)

Date: November 19, 2009 01:56 AM
Author: Loco
Subject: Gluing Quality Issue !!!

Thanks dave,

We have our problem down to the stencil (printer). We are unaware of any design rules concerning aperatures on glue stencils, does anyone know of any?

(http://www.smtnet.com/distributed_forums/Index.cfm?CFApp=8&Message_ID=60476)

Gluing Quality Issue !!!				CooLepse	11/03/09
Gluing Quality Issue !!!				davef	11/03/09
	Gluing Quality Issue !!!			CooLepse	11/04/09
		Gluing Quality Issue !!!		davef	11/04/09
Gluing Quality Issue !!!				rajeshwara	11/04/09
	Gluing Quality Issue !!!			CooLepse	11/05/09
		Gluing Quality Issue !!!		Lynn Norman	11/05/09
			Gluing Quality Issue !!!	CooLepse	11/12/09
	Gluing Quality Issue !!!			Loco	11/13/09
		Gluing Quality Issue !!!		davef	11/13/09
			Gluing Quality Issue !!!	Loco	11/19/09