lol.....If only they all interpreted it that way! I just received pics
under 40x of coating around the base of a pin and the customer demanding to
know why we did not catch it in *our* inspection.
Lloyd Duso
Plant Manager
Diamond-MT
(814) 535-3505
www.Diamond-mt.com
On Thu, Sep 22, 2016 at 11:22 AM, Douglas Pauls <
[log in to unmask]> wrote:
> In addition to the good comments already posted, keep in mind that all
> specifications for coating thickness refer to flat unencumbered areas of
> the board, not component edges. So unless they specify some minimal
> coating on component edges (and a method to measure it on component edges)
> then there is no technical basis for rejecting as "too thin". The question
> of "is the coating there or is it not" is a different question and can be
> determined with either black light or normal light. In terms of
> inspection, J-STD-001 and the industry standard is 4X max. So when people
> find defects at 20X, it is not a defect.
>
>
> Doug Pauls
> Principal Materials and Process Engineer
> Rockwell Collins
>
> On Thu, Sep 22, 2016 at 9:27 AM, Stadem, Richard D. <
> [log in to unmask]> wrote:
>
> > Absolutely correct.
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of lduso -
> Diamond-MT.com
> > Sent: Thursday, September 22, 2016 9:19 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] Fwd: coating complaint
> >
> > A very common mistake people make: if it does not glow, then there cannot
> > be any coating there. It's hard to deny that it is present when you can
> > plainly see the material under white light. Granted, it may not be at the
> > minimum thickness required but it is there. I like inspecting the overall
> > coating under white light first and use the UV light to inspect the
> > coating-free areas that are tougher to see.
> >
> > Lloyd Duso
> > Plant Manager
> > Diamond-MT
> > (814) 535-3505
> > www.Diamond-mt.com
> >
> > On Thu, Sep 22, 2016 at 9:56 AM, Guy Ramsey <[log in to unmask]>
> wrote:
> >
> > > I am in over my head. I have little to no experience with conformal
> > > coating. Can anyone with more experience comment?
> > > thanks,
> > > Guy
> > > ---------- Forwarded message ----------
> > > From: Guy Ramsey <[log in to unmask]>
> > > Date: Thu, Sep 22, 2016 at 9:51 AM
> > > Subject: Fwd: coating complaint
> > > To: [log in to unmask]
> > >
> > >
> > > I sent this message on to a friend who posts images for review by
> > > members of the IPC technet.
> > > We are looking for technical support and user experiences with this
> > > material.
> > > If we inspect at 5x-10x magnification we can observe the conditions
> > > that our customer is complaining about.
> > > But, our application process seems well controlled and the condition
> > > does not exist when the material is first dispensed. The material
> > > flows as it cures and becomes thin at the edges of the components.
> > > Thin enough so that is does not glow under UV light. In some instances
> > > components appear to have no coating (when viewed under UV). However
> > > under normal light it is easy to see the parts are coated.
> > > Is this normal behavior for the material? Can we expect normal
> > > performance from the the coating?
> > > Guy Ramsey
> > >
> > > ---------- Forwarded message ----------
> > > From: Guy Ramsey <[log in to unmask]>
> > > Date: Thu, Sep 22, 2016 at 9:41 AM
> > > Subject: coating complaint
> > > To: Steve Gregory <[log in to unmask]>
> > >
> > >
> > > Hi Steve,
> > > Can you post these images on your homestead page for the group please?
> > > The images are of acrylic coating Humiseal 1B31. We are applying a
> > > thinned mix using a dispenser through a fine needle (25AWG).
> > >
> > > Under room lighting we can see coating. Under UV light, at this
> > > magnification our customer is complaining about skips. I don't have
> > > enough experience with the material to know if this is normal or not.
> > > Notice how the resistor appears to have no coating under UV, but in
> > > normal light it is clearly coated.
> > > Also notice how the coating flows off of the components at the edges,
> > > leaving only a thin coating that may not glow under UV light.
> > > Are these normal attributes of this type coating.
> > >
> > > We do not see this with Urethane spray coatings.
> > >
> >
>
|
