I have been thinking of designing an AT91SAM9261 based board, it will have NAND
flash as storage and SDRAM as memory. It will also have an lcd and will be
running linux.
Im only a hobbyist so and im not sure if i can do the BGA reflowing, practice
makes perfect.
Anyways, my first question is that would i be able to run an 4.2" 420x272 TFT
LCD without too much of performance hit?
Second, would i be able to design a board with only 2 layers for this chip, or
do i need to do a 4 layer pcb?
Any suggestions for NAND and SDRAM ics would be greatly appriciated, i was
thinking of like 512mb of nand and 64 or 128mb of sdram.
Thank you!
Designing an AT91SAM9261 based board
Started by ●July 17, 2008
Reply by ●July 17, 20082008-07-17
--- In A..., akselii@... wrote:
>
> I have been thinking of designing an AT91SAM9261 based board, it
will have NAND flash as storage and SDRAM as memory. It will also
have an lcd and will be running linux.
>
> Im only a hobbyist so and im not sure if i can do the BGA
reflowing, practice makes perfect.
>
> Anyways, my first question is that would i be able to run an 4.2"
420x272 TFT LCD without too much of performance hit?
>
> Second, would i be able to design a board with only 2 layers for
this chip, or do i need to do a 4 layer pcb?
>
> Any suggestions for NAND and SDRAM ics would be greatly
appriciated, i was thinking of like 512mb of nand and 64 or 128mb of
sdram.
>
> Thank you!
>
The chances of success with any less than 6 layers is remote. You'll
probably need to use 3 x 3 mil trace/space to get all the inner pins
out from under the package.
You'll also have to learn about blind/buried vias. Not sure if
anyone has found a fab shop that can do a prototype volume (3-5 pcs.)
for less than $300/board but if anyone has please let me know. I use
Sierra Express in Sunnyvale, CA, and their quotes are on the order of
$300 ea. even if I panelize the board.
>
> I have been thinking of designing an AT91SAM9261 based board, it
will have NAND flash as storage and SDRAM as memory. It will also
have an lcd and will be running linux.
>
> Im only a hobbyist so and im not sure if i can do the BGA
reflowing, practice makes perfect.
>
> Anyways, my first question is that would i be able to run an 4.2"
420x272 TFT LCD without too much of performance hit?
>
> Second, would i be able to design a board with only 2 layers for
this chip, or do i need to do a 4 layer pcb?
>
> Any suggestions for NAND and SDRAM ics would be greatly
appriciated, i was thinking of like 512mb of nand and 64 or 128mb of
sdram.
>
> Thank you!
>
The chances of success with any less than 6 layers is remote. You'll
probably need to use 3 x 3 mil trace/space to get all the inner pins
out from under the package.
You'll also have to learn about blind/buried vias. Not sure if
anyone has found a fab shop that can do a prototype volume (3-5 pcs.)
for less than $300/board but if anyone has please let me know. I use
Sierra Express in Sunnyvale, CA, and their quotes are on the order of
$300 ea. even if I panelize the board.
Reply by ●July 17, 20082008-07-17
--- In A..., "chipburnssc" wrote:
>
> The chances of success with any less than 6 layers is remote. You'll
> probably need to use 3 x 3 mil trace/space to get all the inner pins
> out from under the package.
3/3 trace/space is awfully fine. I can't imagine that will be needed.
0.8 mm is 32 mil. Assuming that half of that is used for pad that
leaves plenty of room for 5/5 rules. Still, that is not something
that the low cost fab houses do at a low price. This will also
require a fine drill diameter, but I don't think it will require blind
or buried vias.
> You'll also have to learn about blind/buried vias. Not sure if
> anyone has found a fab shop that can do a prototype volume (3-5 pcs.)
> for less than $300/board but if anyone has please let me know. I use
> Sierra Express in Sunnyvale, CA, and their quotes are on the order of
> $300 ea. even if I panelize the board.
When I price boards I usually find that there is a minimum total they
want for running the batch. It can be no more money to get 10 boards
as it is to get 1. But there is an outfit that does small quantity by
sharing a panel with other customers. There are restrictions on the
stackup and some other things and it is very slow, a couple of weeks I
think. But it can be cheap. I can't recall the name of the outfit.
I used Sunstone for my last job and I would not recommend them. On
two boards they screwed up three times!!! It cost me a lot of time in
my schedule and I will never use them again. But they were cheap. A
lot of 5 large, 4 layer boards (8" x 10") was under $1000. They also
priced the other boards lower by using panels. They worked out to a
pretty good price, but I ordered 132 (6 panels) of them. It was only
a couple hundred more than getting 22 (1 panel).
Rick
>
> The chances of success with any less than 6 layers is remote. You'll
> probably need to use 3 x 3 mil trace/space to get all the inner pins
> out from under the package.
3/3 trace/space is awfully fine. I can't imagine that will be needed.
0.8 mm is 32 mil. Assuming that half of that is used for pad that
leaves plenty of room for 5/5 rules. Still, that is not something
that the low cost fab houses do at a low price. This will also
require a fine drill diameter, but I don't think it will require blind
or buried vias.
> You'll also have to learn about blind/buried vias. Not sure if
> anyone has found a fab shop that can do a prototype volume (3-5 pcs.)
> for less than $300/board but if anyone has please let me know. I use
> Sierra Express in Sunnyvale, CA, and their quotes are on the order of
> $300 ea. even if I panelize the board.
When I price boards I usually find that there is a minimum total they
want for running the batch. It can be no more money to get 10 boards
as it is to get 1. But there is an outfit that does small quantity by
sharing a panel with other customers. There are restrictions on the
stackup and some other things and it is very slow, a couple of weeks I
think. But it can be cheap. I can't recall the name of the outfit.
I used Sunstone for my last job and I would not recommend them. On
two boards they screwed up three times!!! It cost me a lot of time in
my schedule and I will never use them again. But they were cheap. A
lot of 5 large, 4 layer boards (8" x 10") was under $1000. They also
priced the other boards lower by using panels. They worked out to a
pretty good price, but I ordered 132 (6 panels) of them. It was only
a couple hundred more than getting 22 (1 panel).
Rick
Reply by ●July 17, 20082008-07-17
--- In A..., akselii@... wrote:
>
> I have been thinking of designing an AT91SAM9261 based board, it
will have NAND flash as storage and SDRAM as memory. It will also
have an lcd and will be running linux.
>
> Im only a hobbyist so and im not sure if i can do the BGA
reflowing, practice makes perfect.
>
> Anyways, my first question is that would i be able to run an 4.2"
420x272 TFT LCD without too much of performance hit?
>
> Second, would i be able to design a board with only 2 layers for
this chip, or do i need to do a 4 layer pcb?
>
> Any suggestions for NAND and SDRAM ics would be greatly
appriciated, i was thinking of like 512mb of nand and 64 or 128mb of
sdram.
>
> Thank you!
>
You can make routing with this chip on 2 layers, it's easily routed
with 10/10 mils spacing/trace width. Only 217 balls 0.8 pitch here ;)
As nand - buy some USB Flash stick and got chip from there :-D 2GiB
is cheap ;) SDRAM can be found in old videocards ;)
WBR TiN
ICQ 86080981
>
> I have been thinking of designing an AT91SAM9261 based board, it
will have NAND flash as storage and SDRAM as memory. It will also
have an lcd and will be running linux.
>
> Im only a hobbyist so and im not sure if i can do the BGA
reflowing, practice makes perfect.
>
> Anyways, my first question is that would i be able to run an 4.2"
420x272 TFT LCD without too much of performance hit?
>
> Second, would i be able to design a board with only 2 layers for
this chip, or do i need to do a 4 layer pcb?
>
> Any suggestions for NAND and SDRAM ics would be greatly
appriciated, i was thinking of like 512mb of nand and 64 or 128mb of
sdram.
>
> Thank you!
>
You can make routing with this chip on 2 layers, it's easily routed
with 10/10 mils spacing/trace width. Only 217 balls 0.8 pitch here ;)
As nand - buy some USB Flash stick and got chip from there :-D 2GiB
is cheap ;) SDRAM can be found in old videocards ;)
WBR TiN
ICQ 86080981
Reply by ●July 18, 20082008-07-18
--- In A..., "Rick Collins"
wrote:
>
> --- In A..., "chipburnssc" wrote:
> >
> > The chances of success with any less than 6 layers is remote.
You'll
> > probably need to use 3 x 3 mil trace/space to get all the inner
pins
> > out from under the package.
>
> 3/3 trace/space is awfully fine. I can't imagine that will be
needed.
> 0.8 mm is 32 mil. Assuming that half of that is used for pad that
> leaves plenty of room for 5/5 rules. Still, that is not something
> that the low cost fab houses do at a low price. This will also
> require a fine drill diameter, but I don't think it will require
blind
> or buried vias.
> > You'll also have to learn about blind/buried vias. Not sure if
> > anyone has found a fab shop that can do a prototype volume (3-5
pcs.)
> > for less than $300/board but if anyone has please let me know. I
use
> > Sierra Express in Sunnyvale, CA, and their quotes are on the
order of
> > $300 ea. even if I panelize the board.
>
> When I price boards I usually find that there is a minimum total
they
> want for running the batch. It can be no more money to get 10
boards
> as it is to get 1. But there is an outfit that does small quantity
by
> sharing a panel with other customers. There are restrictions on the
> stackup and some other things and it is very slow, a couple of
weeks I
> think. But it can be cheap. I can't recall the name of the
outfit.
>
> I used Sunstone for my last job and I would not recommend them. On
> two boards they screwed up three times!!! It cost me a lot of time
in
> my schedule and I will never use them again. But they were cheap.
A
> lot of 5 large, 4 layer boards (8" x 10") was under $1000. They
also
> priced the other boards lower by using panels. They worked out to a
> pretty good price, but I ordered 132 (6 panels) of them. It was
only
> a couple hundred more than getting 22 (1 panel).
>
> Rick
>
Rick,
You should check out Sierra Proto Express and their "No Touch"
service:
http://www.protoexpress.com/
You may need to create an account. They will make 4-layer 100 sq/in
PCBs for ~$100 ea. There are some restrictions (min 6/6 width/space)
but for medium sophistication boards they're a really good deal.
They also have a pretty good tech support group. It was from them
that I learned about the epoxy back-fill and overplate processes
required for BGA pads.
Lastly I got the 3/3 suggestion from a board designer from
Flextronics. As I recall Sierra & I came up with the 5/5 spec but I
have yet to build a BGA board myself yet so I deferred to the
experience of a guy who designs for high volume/quality.
Chip
wrote:
>
> --- In A..., "chipburnssc" wrote:
> >
> > The chances of success with any less than 6 layers is remote.
You'll
> > probably need to use 3 x 3 mil trace/space to get all the inner
pins
> > out from under the package.
>
> 3/3 trace/space is awfully fine. I can't imagine that will be
needed.
> 0.8 mm is 32 mil. Assuming that half of that is used for pad that
> leaves plenty of room for 5/5 rules. Still, that is not something
> that the low cost fab houses do at a low price. This will also
> require a fine drill diameter, but I don't think it will require
blind
> or buried vias.
> > You'll also have to learn about blind/buried vias. Not sure if
> > anyone has found a fab shop that can do a prototype volume (3-5
pcs.)
> > for less than $300/board but if anyone has please let me know. I
use
> > Sierra Express in Sunnyvale, CA, and their quotes are on the
order of
> > $300 ea. even if I panelize the board.
>
> When I price boards I usually find that there is a minimum total
they
> want for running the batch. It can be no more money to get 10
boards
> as it is to get 1. But there is an outfit that does small quantity
by
> sharing a panel with other customers. There are restrictions on the
> stackup and some other things and it is very slow, a couple of
weeks I
> think. But it can be cheap. I can't recall the name of the
outfit.
>
> I used Sunstone for my last job and I would not recommend them. On
> two boards they screwed up three times!!! It cost me a lot of time
in
> my schedule and I will never use them again. But they were cheap.
A
> lot of 5 large, 4 layer boards (8" x 10") was under $1000. They
also
> priced the other boards lower by using panels. They worked out to a
> pretty good price, but I ordered 132 (6 panels) of them. It was
only
> a couple hundred more than getting 22 (1 panel).
>
> Rick
>
Rick,
You should check out Sierra Proto Express and their "No Touch"
service:
http://www.protoexpress.com/
You may need to create an account. They will make 4-layer 100 sq/in
PCBs for ~$100 ea. There are some restrictions (min 6/6 width/space)
but for medium sophistication boards they're a really good deal.
They also have a pretty good tech support group. It was from them
that I learned about the epoxy back-fill and overplate processes
required for BGA pads.
Lastly I got the 3/3 suggestion from a board designer from
Flextronics. As I recall Sierra & I came up with the 5/5 spec but I
have yet to build a BGA board myself yet so I deferred to the
experience of a guy who designs for high volume/quality.
Chip
