TECHNET Archives

May 1999

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Ryan Jennens <[log in to unmask]>
Reply To:
"TechNet E-Mail Forum." <[log in to unmask]>, Ryan Jennens" <[log in to unmask]>
Date:
Fri, 14 May 1999 15:13:00 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (93 lines)
Did that send more than once? I could not tell if it was sending because of
the confusing messages I got from the Technet server.  With this new system,
it does not send a copy to me (the sender) as it did with the old,
confirmation style, system.  I apologize if multiple copies were sent.

-Ryan Jennens
TelGen Corporation

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, May 14, 1999 2:53 PM
To: TechNet E-Mail Forum.; Ryan Jennens
Subject: Re: [TN] FW: Fine Powder Solder Paste





Holy smoke! If no-one else is gonna answer this one, I guess I'd better....

Assuming perfect release from the stencil, a 90% by weight metal solder
paste
will give you 50% or so by volume (varying with the flux-type) of metal
INDEPENDENT of the particle size, as long as the aperture dimensions are an
order of magnitude or so larger than the diameter of the solder powder.
However,
as the apertures shrink relative to the solder powder, at some point the
powder
particles will become too big to fit through. Your 20mil pitch situation
fits
somewhere between these two extremes.

If you read the J-STD-006 (and its amendment 1), the size 4 specification is
just a kind of slightly tighter-spec'ed version of size 3. The very largest
size
'3' powder particle is only 53µm (microns) or 2.1mils, compared to the
largest
for size 4, which is 45µm or 1.8mils across: not much difference at all.

Beware: in reality, some vendors' interpretations of 'size 4' can be very
broad
(i.e. a lot of fines), which may lead to fish-egg solderballing and short
stencil-life. The short stencil-life is attributable to increased tackiness
of
the paste, which retains the paste in the apertures, and consequently may
give
you a lower volume deposit than previously seen with size 3!

If you're home-plating because of capillary balls under passives, always
remember to reduce the aperture volume at each end of the component by the
volume of the capillary ball.

Cheers,

Andy





Ryan Jennens <[log in to unmask]> on 05/14/99 02:11:51 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
to
      Ryan Jennens <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Andy Mackie)
Subject:  [TN] FW: Fine Powder Solder Paste

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################


ATOM RSS1 RSS2