Good points, there are other considerations.
For example if designing for mixed technology, through hole inserters have
clinch heads that fly near component leads. SMT parts that are too close
will be damaged. Wave solder shadows are a concern. Proximity to BGAs may
prevent rework tools from being used properly, same with those component
removal tools for soldering irons. Then there is design for test and design
for inspection which are subsets of DFM. And as Shawn mentioned, these must
consider neighboring components.
Setting up a good DFM rule set is invariably specific to the manufacturing
equipment and the service environment of the assembly.
DFMA anyone?
Guy
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Upton, Shawn
Sent: Tuesday, October 18, 2011 8:36 AM
To: [log in to unmask]
Subject: Re: [TN] SMD Component spacing guideline -- help required
Pick and place can get tighter; but rework considerations would tend to push
out parts.
My rule of thumb: my layout software has an IPC footprint generator, and on
most "short" components I live with whatever the automatically generated
courtyard it makes. Typically, just a silkscreen box, manually drawn around
the component, makes enough space for manual soldering-the space taken up by
the designator makes it even better.
I haven't come up yet with a good rule of thumb for taller components
(relays for example). The shorter the component the closer it can be to a
tall one. Often, if I can, I will use a "short" 1206 package between "tall"
relays, as it acts as a natural spacer, keeping the tall relays apart-yet
everything can be soldered. But I don't know how to formulize a rule that
is conditional on the height of the components in question.
Just my general observations from the mostly hand soldered boards that I
design.
[One note: I've long been of the mindset that PCB layout engineers really
ought to learn how to solder. It'd keep some of the more basic mistakes
from happening.]
Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
[log in to unmask]
603.626.2429/fax: 603.641.5336
From: prashant chopra [mailto:[log in to unmask]]
Sent: Tuesday, October 18, 2011 8:18 AM
To: Upton, Shawn
Subject: RE: [TN] SMD Component spacing guideline -- help required
pick and place
--- On Tue, 18/10/11, Upton, Shawn <[log in to unmask]> wrote:
From: Upton, Shawn <[log in to unmask]>
Subject: RE: [TN] SMD Component spacing guideline -- help required
To: "TechNet E-Mail Forum" <[log in to unmask]>, "prashant chopra"
<[log in to unmask]>
Date: Tuesday, 18 October, 2011, 5:46 PM
Hand solder or pick and place?
Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
[log in to unmask]<http://in.mc1373.mail.yahoo.com/mc/compose?to=supton
@allegromicro.com>
603.626.2429/fax: 603.641.5336
-----Original Message-----
From: TechNet
[mailto:[log in to unmask]<http://in.mc1373.mail.yahoo.com/mc/compose?to=TechNe
[log in to unmask]>] On Behalf Of prashant chopra
Sent: Tuesday, October 18, 2011 8:12 AM
To:
[log in to unmask]<[log in to unmask]" target="_blank">http:[log in to unmask]
G>
Subject: [TN] SMD Component spacing guideline -- help required
Hi,
I am working on putting together a spacing guideline for the SMD Component
spacing. I need help and suggestions as to what should be the standard and
minimum spacing requirements for different packages of components? Does
anybody has any guideline document in place for this which can be shared?
example --- I would like to put in spacing required say between two 0603
components, or between a 1206 and 0805 packages or between a SOIC and nearby
SMD component.
Your inputs and comments are valuable.
Thanks.
Regards
Prashant
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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 or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
