Hi all,
Thanks for the perspectives... it seems that there are plenty of
things worth exploring, even if early attempts are basic.
On 5/17/06, Jack Carroll <[EMAIL PROTECTED]> wrote:
On Wed, May 17, 2006 at 09:04:09AM -0700, Nick LaForge wrote:
>
> How far can a electronics hobbyist go before he hits manufacturing
> limitations? I recently read a few articles describing methods to
> etch a blank PCB by pouring acid over a laserjet printed toner layout
> that resists acid, creating a finished PCB. One could then add
> capacitors, resistors, and ICs... but how far can one go? I
> understand that making one's own PCB would yeild less precision and
> could thus never achieve the same density as commercial productions,
> but is it enough to build one's own computer hardware? For example, a
> PCI card? Forgive my ignorance, but doesn't the ability to make one's
> own PCBs only put ICs and microcontrollers out of our reach, which can
> all be bought individually?
Well, to start with, there are alternatives to making your own bare
PCBs. The back pages of every issue of EE Times are full of ads from PCB
vendors that offer all kinds of low-cost services. You can get a couple
pieces of a simple double-sided board for under US $100. Even four-layer
boards are well within an individual's price range, as long as you don't
need special processes such as gold-plated edge fingers. Services and
options vary considerably, so it pays to go to their web sites and intensely
study the fine print.
I'd say the real obstacle is generating the artwork in the first
place, if you're doing anything at all dense. Affordable PCB layout
software is in a fairly early stage of development, and from what I've
heard, not all that capable or easy to use. You want output as a Gerber
file or RS-274X format, for compatibility with widest range of fab vendors.
Simple designs might be doable with a mechanical drafting package such as
QCAD, but anything complicated would be very laborious to do that way.
You'd probably have to generate the output as PDF.
Hand assembly is obviously easier with through-hole components, but
it's certainly possible to do it with surface mount parts down to 0603.
Mostly, it just takes the right tools and materials, such as a decent
microscope and illuminator, and a temperature-controlled iron with an
assortment of small tips -- not especially expensive. You can go smaller,
but it gets more skill-intensive. I recommend a no-clean rosin solder paste
for home assembly; it's much more forgiving than aqueous flux. Stick with
top brands such as Kester or Alpha; anything you save on mediocre soldering
fluxes is simply not worth the aggravation.
Bare-die assembly is not something I would care to tackle at home.
That takes a wire bonder starting at around $1500 used, and a
temperature-controlled oven, along with some expensive resins that aren't
available in small quantities and have poor shelf life even at dry-ice
temperatures. However, there are contract assemblers that can do it if you
need it.
Custom ICs are obviously out of reach, but you can generally get
around that by assembling the required functions from off-the-shelf ICs and
discrete components. It's no different in professional design, when you
don't have the volume to justify the up-front cost of a custom or semicustom
chip.
And, if the project is interesting to enough people, you can make it
a group effort and divide up the work, like OGD1.
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Nick LaForge
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