Steve,
I am not sure what to make of your posting. Let me make some assumptions.
I assume when you say you are using Fugi CP6's, you might be talking about
the Fuji GL5 adhesive dispensors (the CP6 is a chipshooter). The inherent
problem with the Fuji dispensors is that they are "air over" machines. Most
of the modern dispensors went over to positive displacement machines 5 years
ago....Not Fuji.
If you are running selective solder, yet have passives that are still
exposed to the wave, then you cannot print adhesive. So let's focus on the
dispense process.
Your .3mm dual nozzle is the right choice- it is big enough to clean and
manage, and can put small enough dots down to work for the 0603 process.
Your dot size needs to be 1.5X to 2.5X- where X is your nozzle diameter. If
you are closer to 1.5X, your consistency will not be so great. I would
focus on a dot diameter of .6mm to ensure a stable dot (surface tension of
dot to board must be 2X of the dot to nozzle surface tension).
Air over machines are tough because volume is dependent on viscosity. A
valve opens for X amount of time and then shuts in an air over machine. If
you were putting down peanut butter on one valve and jelly in another, then
with the same dispense time, you would get twice as much jelly (thats how I
like my sandwich!!!).
The viscosity of adhesive will change will temperature, and to some extent
can be affected by the volume of adhesive in the syringe.
A positive displacement machine would put down the same volume of each. It
simply fills the chamber (usually a archimedes screw), and turns the auger X
degrees to displace/ or dispense an exact and repeatable amount...
For an air over machine, the more adhesive you put down, the lower the
variation between dots. The variation should only be about +/-10% of the
dot diameter, thus for a .6mm dot you should see .6mm +/-.06mm. If you are
seeing more than this you need to increase your dot size such that it is at
least 2X the inside diameter of the nozzle.
If that is too much adhesive, then move to a smaller nozzle.
If you are in a hot environment, the GL5 machine has a air conditioner
option (it is a stand alone unit). If you have some money to burn, check
out a positive displacement machine. I like the Camelot 2800 machine
because it is cheap (although very slow). Perhaps you could pick up a cheap
used Camelot Gemini machine if you need high speeds. I do not want to
discount Asymtek, Universal, GPD, Creative Automation, or any other
dispensor company whom surely create equally superb products, my experience
has just been with Fuji and Camelot.
Steve A
> -----Original Message-----
> From: Stephen Owen [SMTP:[log in to unmask]]
> Sent: Wednesday,November 14,2001 6:36 AM
> To: [log in to unmask]
> Subject: [TN] 0603 Components.
>
> We are having some problems with 0603 components on adhesive, we are
> running Fugi CP6's. Using 0.3mm dual nozzles, don't seem to be able to get
> the consistency of the adhesive dot right.
>
> Many thanks
> Steve.
>
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