foot prints and protel

[Chris]

Hi,
Im doing board layout for the first time, little more to it than i first
thoght. I have a couple questions that am hoping someone can answer.

1. Do all these different foot prints follow much of any standard? Should
most foot prints be already available in protel or do must have to be made?
For example, I cant really find all the different SMT resistor footprints
anywhere. But I also dont really recognize the strange names most foot
prints seem to have.

2. When using protel, is it best to copy all schematic parts and foot
prints into your own libraries?

3. Is there some reason the supplied libraries have a different schematic
part for every package? I through you would just have the part once and
then choose either DIP,PLCC etc..

4. I copied the resistor from the internal library to my own library (cause
i wanted to give it SMT footprints (how come these aren't already supplied,
why are the caps and resistors all through hole?)) but now for some reason
the pin numbers refuse to stay hidden . The 'show all pins on sheet (even
if hidden)' option in the properties dialog is always checked true, and
refuses to remember me unchechking it. Whats the deal?

Many thanks for any help,
Chris

 

[Brad Velander]

Chris,
here are my comments.
1) Supposedly Protel libraries are made to IPC standards, they are also
supposedly done to an ISO standard within Protel. Does that make them
correct and error free, not a chance.

2) It would be best to review each symbol or footprint you plan to use
and then move them to a custom library. If you later update a library your
checked or corrected parts will not get overwritten.

3) Each different package has either a different pin number scheme or
different pin numbers for the same pin. If they truly were identical than
one symbol would be sufficient, however this is usually not the case. At the
very least there are usually different GND or VCC pins and possible
additional GNDs or other differences.

4) Not sure, never seen that check option in the library part creation.
However did you save the part after making your check box change? Does that
checkbox appear somewhere in the schematic options/config as well and it is
not similarly selected there (under Options, Defaults or some where
similar).

--
Sincerely,
Brad Velander

"Chris" <chris_becker@shaw.stuipdspam.ca> wrote in message
news:e3OAb.592588$6C4.448497@pd7tw1no...

Hi,
Im doing board layout for the first time, little more to it than i first
thoght. I have a couple questions that am hoping someone can answer.

1. Do all these different foot prints follow much of any standard?
Should
most foot prints be already available in protel or do must have to be
made?
For example, I cant really find all the different SMT resistor footprints
anywhere. But I also dont really recognize the strange names most foot
prints seem to have.

2. When using protel, is it best to copy all schematic parts and foot
prints into your own libraries?

3. Is there some reason the supplied libraries have a different schematic
part for every package? I through you would just have the part once and
then choose either DIP,PLCC etc..

4. I copied the resistor from the internal library to my own library
(cause
i wanted to give it SMT footprints (how come these aren't already
supplied,
why are the caps and resistors all through hole?)) but now for some reason
the pin numbers refuse to stay hidden . The 'show all pins on sheet (even
if hidden)' option in the properties dialog is always checked true, and
refuses to remember me unchechking it. Whats the deal?

Many thanks for any help,
Chris