pc bds was Re: re: Smart box / Dumb box

ballendo wrote:

> Jeff, list,
>
> As long as we're talking pc bds, a few pointers:
>
> 1) Work WITH your vendor to reduce cost. Preferably BEFORE you

commit

> to bd size and layout. Learn THEIR "preferred" way to work, and
> what "standard" REALLY means. YOU may think leaving the solder mask
> off will save you money, In fact, it might mean 'pulling' your job
> out of the normal flow, and cost you more.
>

Wally K. replys:

You have point number 1 right.

> ballendo wrote:
> 2) Accept that it will take some time for you to accomplish the
> above. Aim for a 'working' relationship and don't jump vendors to
> save a buck or two...

Wally K. replys:

Poor advice. I know 2 people who own PCB shops and have researched
many on the web. PCB's are sold by a formula they have. The name of
the customer rarely if ever comes in to play. In fact i was with one
of my friends when this came up.

> ballendo wrote:
> 3) Realise that its about holes and size. Also realise that if you
> can cut 'em apart, they usually don't care whether the "Board" they
> make for you is REALLY 25 boards. You do have a CNC, right:-)
>

Wally K. replys:

You almost have it right. If you put more than 1 kind of board on a
pannel it ticks them off a little but they do it. Some PCB shops
will tell you it throws off thier current density and they will not
guaranty even plating. Yes size matters. Number of holes depends on
the vendor. Most have a don't care policy up to so many holes and
sizes.

> ballendo wrote:
> 3a) Use std. drill sizes(see #1 above) and use as few as possible.
>

Wally K. replys

Oversimplistic advice. Some PCB shops have standard drill sizes and
most have max holes they will drill before they charge more. Other
PCB shops have all number drill sizes and many fractional available
as standard.

> ballendo wrote:
> 4) Consider the use of the bds. For example, if it makes sense with
> your vendor, and you are doing the assy. yourself, leave off the
> silkscreen. Or the plating. Or the solder mask.
>

Wally K. replys:

You got this one right, i have left off silkscreen and soldermasks.

> ballendo wrote:
> 5) Find out where the tradeoffs balance. If you want 2 oz. copper,
> but the 'norm is 1 oz., what size can you make the traces in 1
> oz.before it costs as much (since the board is bigger) as 2 oz. on
> the smaller board.
>

Wally K. replys

Once again oversimplistic. The cost of 2oz copper is vendor
dependent. The PCB shop i usally use does not charge extra for 2oz
copper.

> ballendo wrote:
> 5a) Find out where the size/holes price break is and design to take
> advantage of it, if you can.

Wally K. replys

You got this one right.

> ballendo wrote:
> 6) Realise that the pc bd business is very competitive and do your
> homework. You don't want them 'dreading' your call...

Wally K. replys:

I can not think of a single reason they would dread your call. Many
customers of the PCB house are required to get 3 quotes for thier
company and the board house knows it. Low bidder wins. Fact of life.

> ballendo wrote:
> 7) If you work with an assy. house, let them order the bds.

(assuming

> you have trust in them) Their overall volume and probable use of
> allthe above points with THEIR vendor may save you money even tho
> they'll "tack on" their markup.
>
> Most of this is just good business, and many will already know

these

> things.
>
> Hope this helps.
>
> Ballendo

Wally K. replys:

I guess anything is possible. They may know of a cheap PCB house you
have not tried.

Hope i have cleared a few things up for you.


Wally K.