EAGLE for Flex Circuit Design

Dear Flexible,

I have just finished (about 3 weeks and 2 boards ago) a tiny (0.265 x 0.265)

single-sided flex-brd that was far easier to layout in EAGLE than to get

consistent across-many-vendors' quotes for.  The area of developing a

flex-brd is just about backwards in development when compared to designing

and obtaining a rigid board of "normal" thicknesses.

Hind-site being 20/20, what I should have done is:

1) Obtain the "capabilities" of the 30 leading flex-houses; then,

2) Chose a working set of parameters that includes as many of the

fabrication houses as possible; including:

    a) minimum trace and space specifications

    b) minimum space between the outer dimension and the nearest copper

    c) minimum hole, pad, and via sizes

    d) any other important copper or dielectric feature for your design; and

3) The minimum and/or maximum thickness for your board (this was a driving

criteria for my design), what is often referred to as stack-up;

4) Whether the flex-brd needs to be "flexible" or just "flex-to-install"

determines many other layout requirements (like bending radius, track size

and alignment, etc.)

...to name just a few...

After all this, I set up a custom Design Rules Check (*dru) file for

developing my little-flex, and then laid it out.  It took about 5% of the

time to lay out the board compared to all of the board house research I had

to do.

post-note: after all the work, the client has now come back with the

decision that they want to change their board to a really thin rigid board.

Why?  (it's the rest of your question...)

Flexible boards can be extremely expensive (especially when dealing with

some of the exotic materials available for some of the stack layers).  Their

processes are similar in some areas, yet radically different in others

compared to rigid board development.  Interestingly, prices are starting to

drop due to competition, and because a lot more flex circuits are being

made.  Flex circuits typically have much smaller physical features

capabilities (traces and spaces down to 3 and 4 mils is very common, 5 mils

copper setback from the edges is also) compared to rigid boards.

Therefore, EAGLE design (except for the Design Rules used) is identical to

rigid board development.  Learn one, you learn them all (AND, AN EXTREMELY

STEEP LEARNING CURVE IT WAS)...

Enjoy,

Tom Gustin

"Nicholas Kinar" <n.kinar@usask.ca> wrote in message

news:4A5437D6.2070904@usask.ca...

Hello--

 

Has anyone used Eagle CAD for flex circuit design?  Is this possible or

even recommended?  If so, then what are some basic design aspects that I

should watch out for?

 

 

Nicholas

Dear Flexible,

I have just finished (about 3 weeks and 2 boards ago) a tiny (0.265 x 0.265)

single-sided flex-brd that was far easier to layout in EAGLE than to get

consistent across-many-vendors' quotes for.  The area of developing a

flex-brd is just about backwards in development when compared to designing

and obtaining a rigid board of "normal" thicknesses.

Hind-site being 20/20, what I should have done is:

1) Obtain the "capabilities" of the 30 leading flex-houses; then,

2) Chose a working set of parameters that includes as many of the

fabrication houses as possible; including:

    a) minimum trace and space specifications

    b) minimum space between the outer dimension and the nearest copper

    c) minimum hole, pad, and via sizes

    d) any other important copper or dielectric feature for your design; and

3) The minimum and/or maximum thickness for your board (this was a driving

criteria for my design), what is often referred to as stack-up;

4) Whether the flex-brd needs to be "flexible" or just "flex-to-install"

determines many other layout requirements (like bending radius, track size

and alignment, etc.)

...to name just a few...

After all this, I set up a custom Design Rules Check (*dru) file for

developing my little-flex, and then laid it out.  It took about 5% of the

time to lay out the board compared to all of the board house research I had

to do.

post-note: after all the work, the client has now come back with the

decision that they want to change their board to a really thin rigid board.

Why?  (it's the rest of your question...)

Flexible boards can be extremely expensive (especially when dealing with

some of the exotic materials available for some of the stack layers).  Their

processes are similar in some areas, yet radically different in others

compared to rigid board development.  Interestingly, prices are starting to

drop due to competition, and because a lot more flex circuits are being

made.  Flex circuits typically have much smaller physical features

capabilities (traces and spaces down to 3 and 4 mils is very common, 5 mils

copper setback from the edges is also) compared to rigid boards.

Therefore, EAGLE design (except for the Design Rules used) is identical to

rigid board development.  Learn one, you learn them all (AND, AN EXTREMELY

STEEP LEARNING CURVE IT WAS)...

Enjoy,

Tom Gustin

"Nicholas Kinar" <n.kinar@usask.ca> wrote in message

news:4A5437D6.2070904@usask.ca...

Hello--

 

Has anyone used Eagle CAD for flex circuit design?  Is this possible or

even recommended?  If so, then what are some basic design aspects that I

should watch out for?

 

 

Nicholas