Hi Paul,
I'm not sure I understand your question. But to clarify the situation.
We have these 132 Lead Ceramic Quad Flat Packages which we recieve
directly from the manufacturer. They have alloy 42 leads with Nickel
then Gold plated on the leads. They come to us with a ceramic tie bar
(which holds the leads in place for electrical test) The ceramic is used
because it won't disrupt the hermeticity test as happens when an organic
material is used. Organic materials absorb enough helium to cause the
fine leak test to fail. So we get these components with large ceramic
tie bars which we remove in trim and form. Because the nickel and gold
must survive the lid seal operations it is typically much thicker than
what you might see on non hermetic components. But because the
components are to be board mounted the gold must be removed and the
leads coated with solder. So, in a nutshell, our customers pay us money
to take their Gold and give them Lead. It's a pretty dandy business.
We prefer to solder dip after trim and form because of the solder build
up on the tooling, the headaches in masking the corners of the tie bar
so that it will still fit in the tool after solder dip, and it upsets
our inspectors because most of our tie bar customers don't want any
bridging on the tie bar itself. Most test the component with tie bar
attached. Also the variation in solder thickness can allow some leads
not to be clamped well during forming which can cause undue stress on
the component.
After solder dip we would typically perform fine and gross leak
(hermeticity testing) followed by lead scanning and conditioning
(straightening bent leads) then send the components on their way.
I'm not sure I suceeded in answering your questions or just creating
more!
Regards, Russ Winslow
Six Sigma
1940 Concourse Drive
San Jose, CA 95131
[log in to unmask]
http://www.sixsigmaservices.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Paul Klasek
Sent: Tuesday, March 09, 1999 2:49 PM
To: [log in to unmask]
Subject: Re: [TN] : How to Tin Actel-CQ132
Hi Russ
could you educate me ; why & how ?
Thanks A lot paul
> ----------
> From: Russ[SMTP:[log in to unmask]]
> Sent: Wednesday, 10 March 1999 4:14
> To: [log in to unmask]
> Subject: Re: [TN] : How to Tin Actel-CQ132
>
> Hi Bill,
> We routinely solder dip the CQ132 for Actel. When we handle them they
> still have their non-conductive tie-bars on them. It is a lot easier
to
> trim the units first then solder dip the leads. If you don't have too
> many you can use the RMA flux and hand dip the components just fine.
Be
> sure to keep the ceramic body out of the solder. Since you don't have
> preheat you don't want to create a significant differential
temperature
> across the component body. You may want your operators to practice
with
> some cheap plastic components first. Depending upon whether the units
> have been burned-in you may see some problems (pin holes and
dewetting)
> at the location of the electrical contact. This can be resolved by
> using a stronger flux. We have a flux specifially formulated for
> tinning fine pitch components if you need a free sample just give us a
> call.
>
> Because of the gold thickness it is usually recommended that you do a
> double dip (especially since you have little control of depth and
time)
> and I assume your pot is static. The trick in getting things just
right
> is to lift one end out of the solder first. In other words the solder
> should break free from pin 1 then pin 2 ... etc. About a 3 degree
> angle should do the trick. You will need a pretty steady hand for
this
> job. Also, you will want to exit the solder relatively quickly to
keep
> the thickness above the typical minimum requirement of 200 microinches
> (if this applies to you).
>
> The solder temperature we use is 250 C. And just for the record our
> machines are automatic and we don't solder dip any components
manually.
> Our experience has taught us that processes manage to change
themselves
> whenever you don't password protect them.
>
> One final word of caution. Every once in a while a gross leak escapee
> gets into the mix. This is a part that is filled with fluorocarbon
> liquid that will pop when it gets hot enough. It can scare the pants
> off of your operators and can splash the solder around so be certain
> they are wearing the proper safety gear.
>
> If you need any further assistance please feel free to contact me
> directly at (408) 526-1350 x 1.
>
> Regards, Russ Winslow
>
> Six Sigma
> 1940 Concourse Drive
> San Jose, CA 95131
>
> [log in to unmask]
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Kasprzak, Bill
(esd)
> US
> Sent: Tuesday, March 09, 1999 9:45 AM
> To: [log in to unmask]
> Subject: [TN] : How to Tin Actel-CQ132
>
>
> Fellow techies:
>
> We are going to be using an Actel CQ132 Ceramic Quad Flatpack (25 mil
> pitch). From a process standpoint I have ordered a die from Fancort to
> form
> the part, and we will be dispensing solder paste through a Camalot
> Poisitve
> Displacement pump (can't stencil due to component location), component
> will
> be placed then run through my Heller 1088 reflow system. All this
> forming
> and dispensing stuff is new to me but the pitch and the reflow is not.
>
> There is one part of the process that I'm taking for granted and that
is
> the
> tinning of the part. The part is received with gold leads.(Doesn't
come
> in
> anything but gold, and besides, the part will not form well with
solder
> on
> the leads) I'm assuming that after the part is formed, I can dip the
> feet
> of the formed part in RMA flux then tin in a 500 degree F solder pot
> like
> any other part, one side at a time. I would then clean the part in
> Flux-Off-CZ then place into my matrix tray to hold until placement
time.
> I'll probably use a vacuum pencil to hold the part.
>
> Is the tinning of this part as routine as I think its going to be or
do
> I
> need to worry about another new process ? Recommendations are needed.
>
> Bill Kasprzak
> Moog Inc.
>
> (Have we hit the 2000 mark yet ? [Just havin' fun Steve, I know how it
> feels])
>
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