Hi, Jean-Francois,
I think you meant "Land Pattern" for your question. If so, and you can't
get recommendations from either the manufacturer or from IPC-SM-782, you
are faced with calculating it for yourself. IPC-SM-782 contains a formula
for working it out, or you can download various calculators from the web,
including IPC's at http://search.ipc.org/sm782/default.asp.
Minimum annular ring depends partly on requirements. MIL spec requires 4
mils wile IPC requires 3 mils for class 3 boards. Its purpose, of course,
is to provide some anchorage for plating into holes, so you will have to
decide how much strength and support you need from a pad versus spec
requirements versus space available. Annular ring is related to drilling of
the holes, not so much for soldering components on to. Sorry, I'm no expert
in through-hole component pad design, but since your lead diameter is 0.8
mm (32 mils), I estimate you would be looking for a pad diameter of around
50 mils (1.25 mm).
It's not usual, in my limited experience in these things, to ask what is
the minimum annular ring for a particular size of hole. What I calculate is
the pad size required for a given finished (plated, if plated) hole
diameter. To the hole diameter, add twice the hole plating thickness, then
add the manufacturing tolerences that your fab house works to, then add
twice the annular ring requirement as determined from MIL/IPC specs,
customer requirements, design requirements or whatever applies.
Manufacturing tolerences include things like photo tooling tolerence,
tooling registration tolerence, lamination registration tolerence, material
shrinkage tolerence, drill bit diameter tolerence, drill positional
tolerence, etch tolerence and so on, and are usually consolidated into a
single root mean square value. Our fab houses like to have pad diameter =
finished hole diameter + 22 mils to guarantee our 4 mils annular ring
requirement, if that's any help.
Best of luck
Peter
"Bissonnette,
Jean-Francois" To: [log in to unmask]
<JBissonnette@W cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST
ABTEC.COM> Aero/ST Group)
Sent by: Subject: Re: [TN] DO-41 footprint size
TechNet
<[log in to unmask]
G>
03/12/02 09:58
PM
Please respond
to "TechNet
E-Mail Forum.";
Please respond
to
"Bissonnette,
Jean-Francois"
Maybe I used the wrong terminology here. Thanks for the dimensions but
that
I
had them already. What I need (and perhaps someone from the design council
could help here) is the pads dimension required to get proper solder joint.
What
we have from our designer at the moment is quite small and honestly it
looks
like a via more than a pad. According to IPC-2221 the minimum annular ring
requirement is only 0.002" which I find pretty small if you want to get a
good
solder fillet. What is the standard annular ring for a 0.050" drilled
hole?
-----Original Message-----
From: Tom Parkinson - Quality System Manager
[mailto:[log in to unmask]]
Sent: Monday, March 11, 2002 4:33 PM
To: [log in to unmask]
Subject: Re: [TN] DO-41 footprint size
DO-41 is THT. See the following:
http://www.ic.nec.co.jp/discrete/english/pkg/do41.html
"Bissonnette, Jean-Francois" wrote:
>
> Hi all,
>
> I need to find information on components footprints. Is there a place on
> the net
> where I could find information on DO-41 footprint? (and other parts) I
tried
> to
> find it on the Motorola website but came up with nothing. If possible
I'd
> like
> to know what is Motorola suggestion for the pad size of these diodes.
>
> Jean-François Bissonnette
> Vérificateur, Contrôle de la Qualité
> Électronique
> Produits et Procédés
> Vapor Rail Inc.
> 10655 Henri-Bourassa O.
> St-Laurent, Qc
> H4S 1A1
>
> (514) 335-4200 x2021
> (514) 335-4231 fax
>
> <<Bissonnette, Jean-Francois.vcf>>
>
> WABTEC CORPORATION CONFIDENTIALITY NOTE
> The content contained in this e-mail transmission is legally privileged
and confidential information intended only for the use of the individual or
entity named herein. If the reader of this transmission is not the intended
recipient, you are hereby notified that any dissemination, distribution, or
copying of this transmission is strictly prohibited.
>
>
----------------------------------------------------------------------------
-----
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send e-mail to [log in to unmask]:
SET Technet NOMAIL
> To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
> Search previous postings at: www.ipc.org > On-Line Resources & Databases
>
E-mail Archives
> Please visit IPC web site http://www.ipc.org/html/forum.htm for
additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
>
----------------------------------------------------------------------------
-----
----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]:
SET
Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]:
SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
---------------------------------------------------------------------------------
[This e-mail is confidential and may also be privileged. If you are not the
intended recipient, please delete it and notify us immediately; you should
not copy or use it for any purpose, nor disclose its contents to any other
person. Thank you.]
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
