Mark/Lisa,

I think not, component manufacturers are good at making
components and not so for recommending land patterns for their
components.  They don't count in everything that goes on to
solder a simple SMT comp from the begining to the end.

When designing land patterns, Some of things you should
consider:
- component tolerance
- board fabrication tolerance
- pick/place accuracy
- which end of component pin/lead the formation of solder fillet
  ocurrs
- amount of extra land area to set aside for robust solder fillet
  formation and good wetting.

By the time, all tolerances are added in, accuracy could be off as
much as 0.2mm.  My recommendation is talk to your mfg
engineer.  Professional SMT Component and Land Pattern Book
by SMT Plus is a good place to start, however my preference is
IPC-SM-782.  Look into the last page of each IPC land pattern
section and the figure will explain tolerance and solder fillet req's

regards
Matthew Park
SMT Manufacturing Engineer
NII - Norsat International Inc.



>>> Lisa Anderson <[log in to unmask]> July 30,
1998  5:32 am >>>
Mark,

Try an inquiry to the manufacturer.  In most cases they have a
suggested land pattern to use for the
product on the specification sheet.

Lisa Anderson
Paradyne Corp
Largo FL

Mark Ross wrote:

> We just bought the land pattern standard, IPC-SM-782 and
found that many
> of the components we are planning to design are not in here
and appear
> (?) to be unregistered.
>
> For instance SOT23-5 is not in the book.  Can anyone
recommend a good
> source for ALL or most land patterns.  A source that has a
proven land
> pattern track record?
>
> I do not want to use the IPC calculator and waste my time on
many
> patterns.  I would like a good resource for this information.  Or
does
> one not exist yet?
>
> Do I understand the process correctly that first a component
must be
> registered with JEDEC and then at some point somehow an
IPC land pattern
> for the component is established?
>
> We do not want to design surface mount products that fail
because of
> poor land pattern definition.  Thanks in advance.
>
> Mark Ross
> Senior Design Engineer
> Whistler Auto-Mation Products.
>
>
################################################################
> TechNet E-Mail Forum provided as a free service by IPC using
LISTSERV 1.8c
>
################################################################
> To subscribe/unsubscribe, send a message to
[log in to unmask] with following text in the body:
> To subscribe:   SUBSCRIBE TechNet <your full name>
> To unsubscribe:   SIGNOFF TechNet
>
################################################################
> Please visit IPC's web site (http://www.ipc.org) "On-Line
Services" section for additional information.
> For technical support contact Hugo Scaramuzza at
[log in to unmask] or 847-509-9700 ext.312
>
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################