Pat McGuine wrote:
>
> Hello:
>
> We have a new design that has 0805s on the bottom of a board that will be
> wave soldered. We have done 1206s for years but our dot for the 1206s is
> too large for the 0805s.
>
> We have a Camalot w/ a rotary displacement pump doing the dispensing. It
> has a mechanical z-axis compensator which allows me to set the height of the
> needle above the board - but not on the fly (micrometer adjustment). We
> cure the adhesive in an IR oven.
>
> I could use some advise. I'm looking for answers to these questions:
> Please don't feel like you have to answer all of them, respond to as many
> (or as few) as you would like.
>
> 1) What adhesive have you been able to acheive good results with? What is
> it's rated viscosity if you happen to know it?
> 2) What needle diameter do you use?
> 3) Do you try to achieve a dot 2x the needle diameter? If not, what size
> dot do you strive for?
> 4) What is the height of the needle above the PCB?
> 5) What air pressure do you use (do you have a rotary displacement pump)?
> 6) Do you use a different size dot for 1206s on the same board. If so, how
> do you achieve the larger dot?
>
> Thanks for any help. I really appreciate it.
>
> -Pat-
>
> -------------
> Patrick McGuine
> Nicolet Instrument
> [log in to unmask]
> (608) 276-6334
Pat,
Loctite 3609 can be dispensed with the following parameters relative to
your questions.
The questions you must answer are: A) Which motor do you have on the
Cam/Alot pump, ie, 1X, 2X, or 3X? (Note: I assume that you have a 635,
642, or 644 pump.) B) What type of auger/screw is in the pump, ie,
standard or other depth? C) What pad spacing do you have for the
0805's and 1206's.
The motor speed and screw type will affect the dispense parameters to
achieve a given dot size. The pad spacing will limit the maximum dot
diameter.
I have worked with Camalot to write a guide for dispensing 3609. E-mail
or call me and I will send it to you.
Adhesive: Loctite Chipbonder(R) 3609
10 cc syringe, Pressure = 12 to 20 psig, enough to supply auger
continuously without "drool". 30 CC--20 to 25 psig
THESE SHOULD BE USED AS STARTING POINTS ONLY, YOU SHOULD VERIFY AND
ADJUST PERFORMANCE AS INDICATED BY YOUR EVALUATIONS.
0805: Pad spacing typically 0.024 to 0.031 inches
Dot diameter target: 0.016 to 0.021
1X motor 23 gauge 0.006 inch stand-off 20 mSec "shot size"
Standard auger 25 0.005 20 27 0.004 30
2X motor, standard auger, half-speed motor
23 see above 10
25 10
2X motor, deep auger, full speed motor
23 see above 10
25 15
1206: Pad spacing typically 0.047 to 0.055
Dot diameter target: 0.031 to 0.037
1X motor, standard auger, full speed
21 0.010 30
23 140
25 140
2X motor, Standard auger, full speed
22 0.008?? 25
23 see above 45
2X motor, Deep auger, full speed
21 20
22 25
I have also used a 23 ga with 0.008" stand-off on the Cam/Alot 665 pump
to dispense 0.033 inch diameter dots using a 50 mSec shot size.
Also, you can adjust "lift-height". This was set at 0.150 inches for
the above.
Let me know if you need any more information.
Larry
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to: *
* [log in to unmask] with <subject: unsubscribe> and no text. *
***************************************************************************
|
