toaster oven? solder PASTE? wha?!?!?

woefully unaware,

Aaron
----- Original Message -----
From: "Alexandre Guimarces" <alexg@IIS.COM.BR>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, December 29, 2001 4:24 PM
Subject: Re: [EE:] homemade CNC pick and place


> Hi, Roman
>
>
> > Hi everyone, has anyone built a home made
> > CNC pick and place machine to do SMD work?
>
>
>     I have the first one built from printer parts and it works but I am
> going for the second one with real guides. The linear guides are cheap
> enough and will give better results. The one I have built is too big, too
> ugly and too slow :-(
>
>     Take a look at www.igus.com and you will find nice linear guides.
> Subscribing to the http://groups.yahoo.com/group/CAD_CAM_EDM_DRO  will
also
> give great insight about CNC machines in general. The design I will be
using
> as the base for my new machine can be seen at
> http://groups.yahoo.com/group/Homebrew_PCBs/files/Dscn0329.jpg . It is the
> best thought machine that I have seem for the purpose we want. It is not
> worth it, in my opnion and by some experience trying, to use old printe
> parts for it. It is cheap enough to make one with the proper mechanical
> parts. You can use simple plastic nuts to drive the screws. The only
> problems is that you will need access to a mill and a lathe to make the
> screws with the proper advance characteristics. You need a screw with big
> advance to make the table move fast. The stepper can be stolen from any
old
> printer. If you decide to go to belts instead of screws for driving the
> table take a look at www.smallparts.com . They have nice parts.
>
> > I have an idea for a new product that will
> > require lots of 0805 SMD parts and I like the
> > thought of using a machine to do glue spots,
> > then pick and place, then once parts are glued
> > I can just hold them into a solder cauldron
> > (with bamboo tongs!) to solder them in one go.
>
>     I prefer using the machine to put solder paste and then the components
> and use the toaster oven method. You do not need any glue !! Even if you
use
> components on both sides of the board you do not need glue at all. The
> solder cauldron will probably not work, the glue could melt and the
> components will not like all that heat on them. I can assure you that the
> toster oven works great. I have more than 3000 boards on the streets done
> that way with no returns caused by bad soldering !
>
> > Any thoughts??
>
>     The problems I have not adequately solved yet are how to control the Z
> axis of the machine cheaply and how to take the components out of the
rolls.
> The Z can be controlled by a hobby servo motor and the components might be
> taken from the rolls by using the Z axis vacumm pen pulling the roll and
> getting the component afterwards. I have not tried that yet. Please tell
me
> if you have a better idea on this areas.
>
>     I have been looking at this problem for a while and if you need more
> information I might have it...
>
> Best regards,
> Alexandre Guimaraes
>
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