Larry
There may be more vias but no component holes, which are larger and take up more space. This liberated typically 10-20% more real estate on inner layers, especially if you use annular rings, which are strongly recommended.
Brian
"Larry W. Burgess" wrote:
> Hello Phillip,
>
> I am surprised to hear you find less holes in a design of SMT over though hole. It has been my understanding for a long time that SMT with all of it's interconnections on the surfaces, actually increases the number of vias in a board design. That is unless you are designing with blind via-in-pad.
>
> Larry
>
> ----- Original Message -----
> From: Brian Ellis <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, May 02, 2000 9:06
> Subject: Re: [TN] Cost Reductions from Converting to SMT
>
> > Richard, Philip
> >
> > More than the components, there are big savings in the PCBs. Not only can you save on
> > surface area, but the fact that you have fewer holes to get in the way, you can often
> > reduce from 6 signal layers to just 4.
> >
> > On the other hand, all the placement equipment is more expensive, the soldering process
> > is more complex with slightly higher fault rates, cleaning, if necessary is horrendous,
> > so it ain't all roses all the way.
> >
> > Without concrete figures, some of my clients have mentioned an overall 5-10% drop in
> > costs (including amortisation), but only after the processes are fine tuned and run in:
> > expect an increase over the first 3-6 months. The biggest savings, if you are a large
> > producer is due to the fact that you stack the bare boards at one end of the line and
> > test the finished assemblies at the other end, with no human intervention between the
> > two.
> >
> > FWIW
> >
> > Brian
> >
> > Richard Hamilton wrote:
> >
> > > Philip,
> > >
> > > I know exactly from where you are coming!! Somewhat of the same scenario
> > > here.
> > >
> > > We are 'moving' into the SM scene reservedly. I am using the component cost
> > > issue to help support the need to change. Based on two non-scientific,
> > > unprofessional, apples to oranges (OK, OK, just wanted to get the point
> > > across!) comparisons, my survey with vendors two years ago indicated a 15%
> > > price reduction by going to SM components. Another survey I just did
> > > indicated a 25% reduction in cost by moving to SM.
> > >
> > > Like I said, this was not a scientific gathering of information, but based
> > > on our parts this increase in reduction means the pricing trend is moving in
> > > a direction that we should consider.
> > >
> > > >From the department of 'For What it is Worth', digest in good health!
> > >
> > > Richard Hamilton
> > > Clemar Mfg. / Rain Bird
> > > [log in to unmask]
> > >
> > > > -----Original Message-----
> > > > From: Philip Poling [SMTP:[log in to unmask]]
> > > > Sent: Tuesday, May 02, 2000 5:47 AM
> > > > To: [log in to unmask]
> > > > Subject: [TN] Cost Reductions from Converting to SMT
> > > >
> > > > Greetings TechNetters,
> > > >
> > > > I'm trying to justify changing some of our circuit assemblies from THT to
> > > > SMT.
> > > > They go into a 40 Ton vehicle, so saving weight or space isn't enough
> > > > justification. I need to be able to show that, at least in some cases,
> > > > you can
> > > > reduce the cost of a circuit assembly by converting it to SMT. For my
> > > > justification, I need to find some examples of how other companies have
> > > > actually
> > > > reduced the cost of a circuit assembly by converting it to SMT.
> > > >
> > > > Have any of you gone through this process and actually reduced the cost of
> > > > a
> > > > circuit assembly? Was the savings significant? Have any of you written
> > > > any
> > > > articles or reports that you could share? Or, has anyone read any
> > > > articles or
> > > > books on the subject?
> > > >
> > > > I'd appreciate receiving any information and examples you have. Exact
> > > > figures
> > > > are not required, just ballpark estimates of cost savings would be very
> > > > helpful.
> > > >
> > > >
> > > > Thanks,
> > > >
> > > > Phil Poling
> > > > United Defense
> > > > 4800 East River Road
> > > > Fridley, MN 55421-1498
> > > > 612-572-6533
> > > > [log in to unmask]
> > > >
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