Parts ordering for Prototype and Production

[webstuff]

Hi,
This is my first foray into making production quantity circuits, I'm
almost ready to design a PCB for an initial prototype, my initially
quanties will be around 50 devices. In production 'hopefully' they will
be in the 10's thousands (i will also possibly consider a contract
manufacturer overseas if it comes to that)

Whats really confusing to me is selecting a parts supplier and
generally figuring out which parts to select.
Here's an excerpt from my BOM header :
- Part Number
- Unit Cost
- 1K Cost
- 10K Cost
- Local Lead Time (for prototype)
- CM Lead Time (for production)
- End of life schedule
- Alternative parts

The parts are typically a 8 bit controller (AVRMega or Freescale etc),
some RF front ends, some amplifiers, descreets etc.

My questions :
- Do those data points look about right in trying to make decisions on
which part to buy? What else would you consider.
Note: I pretty much have 2 separate routes I could take in selecting
the MCP and RF so thats not an issue.
- How do folks usually go about getting parts? i.e. for a prototype (50
nos) would you go to a single supplier (Avnet/Digikey/Mouser etc) for
'ALL' parts or would you stagger your buying based on
pricing/availability etc.
- Not all of these supplier sites have all the data i'm looking for,
i.e. digikey doesn't show lead times. Whats a good way to go hunting
for all of this info (the number of items I have are around 30- its a
pain to try and hunt them down individually)
- Whats your typical strategy for selecting suppliers for local and
contract manufacturing (asia)?
- Whats up with WIERD lead times, looked up a MCP's lead time and it
shows anywhere from 17 to 99 week leadtimes for almost all parts of
that family. (havn't spoken to the manf yet though). Thats a tough call
to make isn't it, decide architecture design etc and then find those
parts have huge lead times.

Any suggestions/advice welcome, i'd also really appreciate it if you'll
could suggest books/sites that could educate me better on these
processes.
Thanks
K

 

[Joerg]

Hello K,

Could you give us your real first name? It's just nicer to communicate then.

- Do those data points look about right in trying to make decisions on
which part to buy? What else would you consider.

It's good you have pricing in there. Most people don't. Create a field
with all manufacturers so you can quickly see how multi-sourced a
certain part is.

- How do folks usually go about getting parts? i.e. for a prototype (50
nos) would you go to a single supplier (Avnet/Digikey/Mouser etc) for
'ALL' parts or would you stagger your buying based on
pricing/availability etc.

All at one place, at that qty. Shipping charges would most likely eat
any advantage otherwise.

- Not all of these supplier sites have all the data i'm looking for,
i.e. digikey doesn't show lead times. Whats a good way to go hunting
for all of this info (the number of items I have are around 30- its a
pain to try and hunt them down individually)

Digikey shows how much is in stock there. If there is no stock I'd be
suspicious. Could it be a boutique part that has the potential to turn
into a purchasing nightmare?

- Whats your typical strategy for selecting suppliers for local and
contract manufacturing (asia)?

Asia: You have to ask around, see what others were happy with. But check
with people who did a similar product. Local: Ask a local distributor.

- Whats up with WIERD lead times, looked up a MCP's lead time and it
shows anywhere from 17 to 99 week leadtimes for almost all parts of
that family. (havn't spoken to the manf yet though). Thats a tough call
to make isn't it, decide architecture design etc and then find those
parts have huge lead times.

Any suggestions/advice welcome, i'd also really appreciate it if you'll
could suggest books/sites that could educate me better on these
processes.

Long lead times = Not a good thing.

Can you design in something more ubiquitous?

My golden rule: If Digikey or a similar place doesn't have it, there has
to be a real compelling reason to design in that part. Usually I cannot
find such a compelling reason ;-)

You can also check other big mainstream distributors such as Arrow:
http://www.arrownac.com/

Now if they don't have stock that would really make me suspicious. After
a while you can establish a good contact there. Besides the pricing
trend that is about the only way to find out how popular a part is,
meaning how many years or decade of product life it might have left.

Regards, Joerg

http://www.analogconsultants.com

 

[Dan Hollands]

You need to build a relationship with the local office of a major parts
distributor. They can help with alternates and will usually know well ahead
of time if a part is being discontinued

--

Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
QuickScore@USSailing.net
www.QuickScoreRace.com


"webstuff" <kwebstuff@gmail.com> wrote in message
news:1122494414.920981.59500@o13g2000cwo.googlegroups.com...

Hi,
This is my first foray into making production quantity circuits, I'm
almost ready to design a PCB for an initial prototype, my initially
quanties will be around 50 devices. In production 'hopefully' they will
be in the 10's thousands (i will also possibly consider a contract
manufacturer overseas if it comes to that)

Whats really confusing to me is selecting a parts supplier and
generally figuring out which parts to select.
Here's an excerpt from my BOM header :
- Part Number
- Unit Cost
- 1K Cost
- 10K Cost
- Local Lead Time (for prototype)
- CM Lead Time (for production)
- End of life schedule
- Alternative parts

The parts are typically a 8 bit controller (AVRMega or Freescale etc),
some RF front ends, some amplifiers, descreets etc.

My questions :
- Do those data points look about right in trying to make decisions on
which part to buy? What else would you consider.
Note: I pretty much have 2 separate routes I could take in selecting
the MCP and RF so thats not an issue.
- How do folks usually go about getting parts? i.e. for a prototype (50
nos) would you go to a single supplier (Avnet/Digikey/Mouser etc) for
'ALL' parts or would you stagger your buying based on
pricing/availability etc.
- Not all of these supplier sites have all the data i'm looking for,
i.e. digikey doesn't show lead times. Whats a good way to go hunting
for all of this info (the number of items I have are around 30- its a
pain to try and hunt them down individually)
- Whats your typical strategy for selecting suppliers for local and
contract manufacturing (asia)?
- Whats up with WIERD lead times, looked up a MCP's lead time and it
shows anywhere from 17 to 99 week leadtimes for almost all parts of
that family. (havn't spoken to the manf yet though). Thats a tough call
to make isn't it, decide architecture design etc and then find those
parts have huge lead times.

Any suggestions/advice welcome, i'd also really appreciate it if you'll
could suggest books/sites that could educate me better on these
processes.
Thanks
K

 

[Joerg]

Hello Dan,

You need to build a relationship with the local office of a major parts
distributor. They can help with alternates and will usually know well ahead
of time if a part is being discontinued

That works well if the production run happens locally. But these days
are long gone and this whole distributor relationship often isn't there
anymore. You or your client gets bids from different assemblers in
various countries. If I design something for a client I usually do not
know where it is going to be produced. Also, my clients rarely do any
mass qty purchasing. That is done by the assembly house in whatever
country it may be. We just spec the parts they have to buy.

When dealing directly with semiconductor manufacturers it was easier. I
got support from an Analog Devices engineer long after moving to another
continent. That was unusual and wonderful, it has landed them quite a
few design-ins.

Regards, Joerg

http://www.analogconsultants.com