I totally agree with Frank on this one.  Silkscreen legend is a
"godsend" for those techs I've spoken with.  This is even more important
as parts get smaller and closer together.  Finding a way to mark all
parts is really tough on some boards - I've seen it add more than a day
to the design cycle, but it usually saves much more than that over the
life of the product.  Of course if you are designing "throw away" boards
where no debug/repair is necessary, marking is not too much of an issue.

We are currently using 50 mil text height with 8 mil thickness.  I've
gone down to 35 mils with 6 mil thickness. We have no trouble with
legibility - but we use 35 mils only when absolutely necessary.  With
Mentor we are also able to regulate the aspect ratio so I usually cut it
to 0.8.

Mark on!!!!

Ben Davis
Systems & Electronics, Inc.
[log in to unmask]

Kimmey, Frank wrote:
>
> Now that there has been a couple of answers here is mine.
>
> I vehemently disagree with JoAnn and Mary on the necessity of silkscreen
> legend. As a QA tool it is unbeatable and inexpensive (not to mention
> the time saved in troubleshooting for rework/repair).
>
> We do high volume consumer (inexpensive, I would say cheap but that
> sounds bad) products. We also put legend on all PCBs. Depending on the
> type of design we use different text heights and weights.
>
> SMD (0805/SOIC) - I have used 35mil tall with 5mil wide lines, though I
> prefer 42mil with 8mil lines. So far I have not experienced any
> legibility problems.
>
> Leaded - I like 60mil tall with 8mil lines
>
> Call me if you want to discuss
> Hope it helps
> FNK
>
> Frank N Kimmey
> EM Designer
> C&K Systems, Inc
> 916-353-5366
> [log in to unmask]
>

################################################################
DesignerCouncil 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 DesignerCouncil <your full name>
To unsubscribe:   SIGNOFF DesignerCouncil 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################