After reading through this a couple of times it looks like Miguel is after a
dedicated board support for the screen printer verses a process pallet. Their
are multiple sources for dedicated board supports. I personally get machined
board supports from Rapid Tooling ( Phone (972)578-1577, contact Dion Casto )
and molded board supports from Transition Automation ( www.SMTexperts.com, Phone
(800)648-3338, Sales Crista ). Both types work well but I have better success
with the molded board supports when the 1st pass side is heavily populated. Oh
forgot to add I'm buying these supports for an MPM UP2000 but both vendors have
experience with other printers.
Richard Jackson
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____________________Reply Separator____________________
Subject: Re: [TN] Screen-printer pallet
Author: Jim Gleason <[log in to unmask]>
Date: 12/23/98 7:00 AM
GSC, www.gogsc.com, 972-494-1911, make many of these. They have two
different types of clamps that are compeltely flush and willnot interfere
with you stencil. One tensions the board and one grabs it. Ask for Hassan,
he knows this stuff inside and out.
jg
-----Original Message-----
From: Stephen R. Gregory <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Tuesday, December 22, 1998 3:55 PM
Subject: Re: [TN] Screen-printer pallet
>In a message dated 12/22/98 8:50:18 AM Pacific Standard Time,
>[log in to unmask] writes:
>
><< Hi all :
>We are doing boards with components on Top and Bottom sides (2 reflows),
1st.
>process is bottom and we do not have any problem, but for the 2nd. process
we
>need a pallet for having a uniform support on the board, because the height
of
>the solder paste is not regular.
>Do somebody have information about a company(ies) that makes this kind of
>pallets for supporting ?
>
> Miguel Angel Pulido>>
>
>Hi Miguel,
>
> In reading the replies to you, it looks like everybody has given you
some
>good sources for pallets. I'd however, like to throw this out there
regarding
>pallets. There's always going to be some boards that's going to require
>fixturing of some sort when being built, be it surface mount,
wave-soldering,
>what have you. But before I go and get pallets, I'll try to do whatever I
can
>to keep from having to use them. Look at the layout and make
recommendations
>to change things to keep the board as flat as possible.
>
>You didn't mention how you ran the first side through reflow...do you use a
>edge rail conveyer? I've had boards warp because of the component density
>running on the edge rails, your answer to your problem could be as simple
as
>running the first side reflow on the mesh belt instead of the edge rails.
If
>its warping on its own,that many times indicates that the copper or
components
>isn't balanced, or distributed evenly throughout the board.
>
>Maybe you have some input to change things, or maybe the board is such that
>things can't be changed. At any rate, the big thing I have against using
>pallets is that they're cumbersome and slow things down, and unless you
have
>big bucks and can afford a whole mess of them, your poor operators wind-up
>putting in quite a few miles running the bloody things from the end of the
>line back up to the beginning. Plus, they inhibit the use of other
automation
>like bare board loaders and unloaders, and will prevent you from running
the
>boards in a "flip-line" (one that does both sides in one pass) if you are
ever
>in a postion to have such a nice line. Also, sometimes they can add to the
>weight of a board so much that they can't travel down the conveyer (I've
had
>that happen a time or two in the past with FUJI machines when I was having
>pallets made from aluminum before all the lighter composite materials
started
>showing up...)
>
>But if you gotta' have pallets, ya' gotta'. Everybody has given you some
good
>sources (SP Precision is one I've used before and they're good, another one
is
>Stone Mountain Tool, they incorporate some unique board clamping systems in
>their pallets)
>
>-Steve Gregory-
>
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