[sdiy] Importance of electrical test at PCB manufacturing?

[cheater cheater]

You've obviously never managed a company like this Dave

>It is in their best interest to make the highest quality
> boards to minimize their cost

No. exactly the other way around. It is in their interest to make the
shittiest, crappiest boards they can get away with. And by 'get away
with' we mean 'protected by contract'. And if you don't pay for the
electrical test/insurance, you don't get a contract on the quality at
all. What's written in the manufacturer's contract, David? And how
does it apply to the chinese law system? And how much would it cost
you to litigate in China with a Chinese interpreter?

In fact as long as they have enough clients coming in to pay for a
rice bowl a day for the workers they are OK. The rent in china isn't
much, and the equipment was paid for already. They probably have more
clients coming in than they can handle. So if they lose some less
important ones (most probably me and you) then they will be happy,
because they will have got some crappy work sold for proper money, and
they don't need the overhead from you anyways.

> It is pretty cynical to think they would manufacture bad boards
> only if you didn't buy the electrical test

But true. Many manufacturers will have a couple production cycles
in-house and they will use the older, crappier one if they can get
away with it.

> so that next time you'd learn
> your lesson and pay for it.

You've paid for it already. You paid for the boards that offset the
initial investment on their brand new equipment which they would have
used if you had paid $140 more. Those boards were, in manufacturing
terms, for free, because they were using older equipment past its
service life expectancy. So they're happy because they get their new
equipment paid for, for free. By you. And if you don't want to pay
them for free in this way, you will pay them $140, which is again free
to them, because it just means that Chen will use the new process and
not the old process. Which is again free, because it's just a 5 second
decision, and that's all. Most probably the new process is also easier
to manufacture in, so again more money for them. So out of this $140,
maybe $90 pays for the electrical test and they get $50 for free. So
either way they get some banknotes off you for free, except they do it
every time if you pay for the electrical test, and they do it only
randomly when you don't pay for it.

>If I received bad boards, and could document
> the fault, I'd probably find another vendor if they didn't replace them at
> their cost.

You and another 7 billion suckers, see
http://en.wikipedia.org/wiki/World_population

Dealing with China is a hit and run business. Do you seriously think
they will care for you if you float away? There are so many fish in
the pond. Get real Dave. Unless you pay for something to be
guaranteed, you can almost certainly assume that you're not getting
it. And if you do, it's just by pure luck. That's not to say it's a
very bad situation for us.

Of course this logic of you 'not getting what you think you pay for'
is offset by manufacturing standards set out by the management, which
are tuned just so that statistically, as you keep on making boards
with them, the cost of not having the $140 cost will be more than
paying that $140 every time. That's for big runs, though. If you get a
single, expensive run of PCBs that is broken, it can cost you much,
much more than $140 - and then you'll be wishing you had taken the
$140 test. However for small runs like ours in the DIY community, if a
single bad run happens, it's not ruining. So statistically speaking,
we win the game, because of our disposition to have small PCB runs
made for us.

D.

On Wed, Oct 7, 2009 at 7:31 AM, Dave Manley <dlmanley at sonic.net> wrote:
> Sorry, I don't get your point.  The manufacturer wants to build the minimum
> number of boards, using the minimum amount of material to yield what the
> customer ordered.  It is in their best interest to make the highest quality
> boards to minimize their cost, and to sell the "insurance" to maximize their
> profit.  It is pretty cynical to think they would manufacture bad boards
> only if you didn't buy the electrical test, so that next time you'd learn
> your lesson and pay for it.  If I received bad boards, and could document
> the fault, I'd probably find another vendor if they didn't replace them at
> their cost.
>
> -Dave
>
> Andreas Wetterberg wrote:
>>
>> *puts on cynic-hat*
>>
>> The problem at hand here is that you have a company that has a vested
>> interest in actually doing bad boards, conditioning people into buying
>> insurance to help correct what could just as easily be intentionally bad
>> service...
>>
>> To me it all sounds like the classic monty python sketch with the mafia
>> shaking down the army: "you wouldn't want any of yer tanks to go... missing,
>> would ya?"
>>
>> /cynic-mode.
>>
>> Andreas.
>>
>> Paul Perry skrev:
>>>
>>> If a board is propely laid out, and only single or double sided,
>>> it would be very unusual inded for there to be an error in the form of a
>>> short or track break.
>>>
>>> I think it has only happened to me twice in thousands of boards.
>>>
>>> paul perry Melbourne Australia
>>> _______________________________________________
>>
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