Hello Peter,

We are actually looking/evaluating BGA rework equipment (this would be our
2nd BGA system) for our lab/proto work.  You have some good things to say
about the PDR lightmaster.  We have not evaluated this system (in part due
to the fact that it is an all IR system...temeperature uniformity might be
an issue).

In all honesty, I am a bit confused about which is better forced convection
or IR.  According to previous evaluations, IR is a plus when we need a fast
ramp (up to 5 degrees per second, compared to up to 4 degrees that could be
achieved with forced air systems)however, 3 degrees per second is the max
that we have ever used.  Forced Convection is a plus in achieving a unifom
temperature across the component.  Most rework systems that I know of are
forced convection systems.  Every rep that demoed their equipment said that
forced convection is the prefered heating source thus most rework systems
on the market are forced air.  Not exactly a scientific answer, but is a
consitent one.  Can you provide some insight on the benefits/disagvantages
of IR/Forced Convection?

The price for the PDR system really makes it affordable.  All of the
systems that we have seen are in the $30-$40k range.  Is $14k for a new
unit with the vision/BGA alignment system, PC, monitor, etc.?  Sounds too
good to be true...lol

Thank You

Sam A.

On Tue, 10 Dec 2002 09:39:11 +0800, [log in to unmask] wrote:

>Hi, Steve,
>
>Yup! We've taken the plunge and bought one after getting the rep to
>demonstrate the removal and replacement of all kinds of things from 2 inch
>square PGA's to plastic and ceramic BGA's, plastic and ceramic LCC's - even
>plastic connectors! We were hugely impressed with it. The guy even showed
>that you could leave the system cooking away while going for a cup of
>coffee and you wouldn't come back to find everything cooked to a crisp.
>Many folks avoid IR because of the misconception that it's not controllable
>- but it is, isn't it? I'm looking forward to having some fun with it once
>it arrives.
>
>I'm interested on your take regarding the thermally consuctive tape. I was
>going to buy a couple of reels of the stuff along with the machine, but was
>told that the tape's function is not actually to transmit heat. Rather, its
>purpose is to improve the emissivity of things like metal-bodied components
>for the feedback sensors that control the amount of heat being put into the
>component. Our rep uses the machine himself for his core business of
>repairing elderly comms equipment cards, and is thus quite an expert in
>using it. It was he who also re-designed the original controller. His
>explanation is that it's component emissivity to the sensors that indicates
>the component temperature and governs the amount of heating that a
>component receives. His experiments have shown that even using the tape,
>indicated temperatures can be out by 20 or more degrees compared with
>actual temperatures. His approach is not to use the tape at all, but to use
>the natural emissivity of the component and derive a number of profiles for
>different component body materials using thermocouples and noting the
>temperature reading on the controller. So if the thermocouple reading shows
>the component is at 190 degrees, for example, but the controller only shows
>150, that's OK. If you like, he's calibrating the controller readings to
>suit a range of component body material types. It makes sense in theory,
>but I don't have the benefit of practical experience yet to prove to myself
>that what he says is valid. It means, though, that I'll have to sit down
>and tabulate what the controller readings should be for the components we
>rework where they're metal or ceramic - the systems "naturally" works best
>for plastic-bodied devices. WHAT D'YA THINK?
>
>I'm relieved to hear that you're still enthusiastic about your machine.
>Maybe we can compare notes from time to time on our findings and
>experiences.
>
>Peter
>
>
>
>Steve Gregory <[log in to unmask]>   10/12/2002 08:34 AM
>Sent by: TechNet <[log in to unmask]>
>
>Please respond to "TechNet E-Mail Forum."; Please respond to SteveZeva
>
>              To:  [log in to unmask]
>              cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
>              Subject: Re: [TN] Table Top Static Reflow Ovens
>
>
>
>
>
>
>
>
>Hi Peter!
>
>So, you guys are buying one? Pretty cool, ain't they? I've had mine for
>about 10-months (or there abouts) now, and love it!! One part that
>sometimes can be a problem I've found out, is PLCC sockets. Just gotta make
>sure that the thermal conductive tape contacts, and is seated well against
>the leads at the top of the sockets so that you get good thermal transfer
>down to reflow the joints.
>
>But otherwise, I haven't run across a part I couldn't rework...even with
>boards being bonded to big, thick, heatsinks. Couldn't even get the solder
>plastic with hot air systems.
>
>-Steve Gregory-
>
>
> Hi, Bev,
>
> Not a reflow oven, but a rework station if you're interested in such a
> thing as an adjunct to your main oven. We have just ordered a PDR
> Lightmaster IR component rework station from a local company here in
> Singapore. They have redesigned the controller unit and the operating
> principle so that it now has a proper feedback loop that controls the
> power
> being put into the components very nicely, and doesn't involve all those
> nozzles that are required for a hot air system and which can cost quite a
> bit.
>
> The basic system costs about US$14K and seems to handle just about
> anything
> once you understand about the emissivity of the different component body
> materials. The company selling the re-modelled systems is Vanco Pte Ltd,
> but they don't have a website. Contact me off-line if you're interested
> and
> I'll give you more details.
>
> Peter
>
>
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