Hi Rosen!
Here's a blast from the past that may help you out.
I asked almost the same question some time back,
and Dave Fish gave me a very good answer...
> ----- Original Message -----
> From: Steve Gregory
> To: [log in to unmask]
> Sent: Monday, June 30, 2003 8:42 AM
> Subject: [TN] Double-sided reflow with Altera RQFP...
> Mornin' All!
> Just a quick question, has anybody ever done a double-sided reflow with a 240-pin Altera RQFP
> on the bottom that has a metal heatsink in the top?
> Thanks!
> -Steve Gregory-
**************************************************************************************************
> Date: Mon, 30 Jun 2003 16:38:09 -0400
> Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>,
David Fish <[log in to unmask]>
> Sender: TechNet <[log in to unmask]>
> From: David Fish <[log in to unmask]> <<http://listserv.ipc.org/scripts/wa.exe?A2=ind0306&L=technet&D=0&I=-3&P=62908>>
> Subject: Re: Double-sided reflow with Altera RQFP... <<http://listserv.ipc.org/scripts/wa.exe?A2=ind0306&L=technet&D=0&I=-3&P=62557>>
> X-To: [log in to unmask]
> Content-Type: multipart/alternative;
> Hi Steve
> We don't double reflow this part. We wouldn't consider it without a fixture or some other support.
> You know that sound, the almost involuntary sound that patrons in a restaurant make when a waiter drops a glass or a tray?
> It's kind of an "oooooo" sound. Well if you run these parts, the sound that the troops at your plant will make will be so loud as
> those pups start Peter Panning to the floor that the people in the front will stop playing games on the computer and walk out
> back to find-out what's going on.
> Do the numbers:
> * Part weight: 15.1 gm
> * Lead toe to heel: 0.46/0.66 mm
> * Lead width: 0.17/0.27 mm
> Lead wetting area = 240* [0.46*0.17] mm^2 = 18.7 mm^2 [0.03inch^2]
> Weight of component to total pad mating area ratio: 15.1 gm / 18.7 mm^2 = 804.6 mgm per mm^2 [519.1 gm per inch^2]
> A commonly acceptable ratio is: 50 mgm per mm^2 [30 gm per inch^2]
> Pushing the boundary ratio is: 44 gm per inch^2
> Dave Fish
********************************************************************************
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
"Rosen D. Arabadzhiev</br>-----------------------------</br>"
Sent by: TechNet <[log in to unmask]>
09/01/2005 03:18 AM
Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to rocko
To: [log in to unmask]@SMTP@Exchange
cc: (bcc: Stephen R Gregory/LABARGE)
Subject: [TN] necessary solder paste volume
Good day all,
Is there anybody who knows how can I calculate the necessary
solder paste volume, which will hold QFPs and BGAs over
bottom side of PCB during secondary side reflow process?
Thanks,
Rosen Arabadzhiev, Process Engineer
CENTILLION LTD
__________________________________________________________________
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