Hi Dan,
Different PCB designs will have different of components (hence
SMT pads or even PTH, believed that you are interested in SMT pads only)
assembled onto its. Weight the PCB before and solder paste printing and
divide it across overall stencil opening (stencil thickness will be
constant e.g 5mils, is another thickness is used you have to evaluate
again)......
Hope this help to start.....
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, 21 May 2008 12:40 AM
To: [log in to unmask]
Subject: [TN] NTC RE: [TN] Average paste volume estimate
Weeeeell. I thin it would be called out on a limb if I had said -20% to
+121%.
Bev
________________________________
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Tuesday, May 20, 2008 12:35 PM
To: TechNet E-Mail Forum; Bev Christian
Subject: Re: [TN] Average paste volume estimate
0-100% eh?
That's what I like about Bev. Never afraid to go out on a limb.......
Doug Pauls
Bev Christian <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
05/20/2008 11:23 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Bev Christian <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Average paste volume estimate
It depends.
The smaller the aperture, the less paste left on the board.
The thicker the stencil the less paste left on the board.
And then you have your aperture ratio that combines the two.
And then there is which specific paste you are talking about.
Etc., etc.
I would say to be safe - between 0 and 100%. But I think we can say it
is usually between 30 and 90%. I am a lab rat, so process engineers may
be able to refine this a bit.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Mathews
Sent: Tuesday, May 20, 2008 12:10 PM
To: [log in to unmask]
Subject: [TN] Average paste volume estimate
Does anyone have an easy way to estimate how much paste is applied to a
smt pcb? I understand it varies on
squeegee pressure, stencil thickness, and pitch of the components but I
was looking for an average. I would
assume that somewhere out there someone can estimate that "2 grams of
paste is used on a 2" x 2" smt pcb".
I will then use this information to determine how much lead is used on
non-RoHS products due to solder paste
issues and not non-compliant components.
Thank You in Advance,
Dan
Dan Mathews C.I.D.+
Engineering Support Supervisor
B&B Electronics
Ottawa, IL USA 61350
Phone: 815-433-5100 ext 217
Fax: 815-434-8831 (direct to my desk)
URL: http://www.bb-elec.com <http://www.bb-elec.com/>
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