I have to say that matching component orientation is nice to see and
easy to work with, but correct library design is way more important. If
any one has had a chance to write a SMT program they know exactly what I
am talking about. The component manufacturer has a data sheet that
basically breaks down where pin one should be on a polarized part, not
all designers or librarians understand that this is crucial to getting
that design right the first time. It takes a programmer hours just to
sift through all the polarized parts to determine if the thetas are
correct. Matching the part in the reel to what the CAD is telling you is
correct is very time consuming, not to mention that you are depending on
the programmer to get it right. Also like to point out that not all
OEM's stay the same contract manufacturer so when you move that design
form one place to the other you will forcing another programmer to do
the same work that has already been completed once before.
Regards,
Ted T.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Thursday, March 01, 2007 9:32 AM
To: [log in to unmask]
Subject: Re: [TN] Component Orientation Survey
Chris,
When you are squeezing 10 pounds into a 5 pound bag I think you're
right. In many of our designs we have the luxury of 5 pounds in a 10
pound bag.
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Ball
Sent: Thursday, March 01, 2007 10:28 AM
To: [log in to unmask]
Subject: Re: [TN] Component Orientation Survey
So... no way around this... it does depend.
For high volume, high automated content, zero re-work policy (heh heh),
very stringent performance requirements, and much pressure for low cost,
I
don't worry much about matching orientations. I know it upsets some
people
some times, but the way I have come to see it, my job is to achieve
minimum upset rather than the total avoidance of upset. Clean routing,
layer count, and PCB size, are just some of the factors that are a
higher
priority.
Solderability is a separate issue. I'm talking about component
orientation
of reflowed SMT parts.
We avoid leaded (leed not led) parts and hand insert ops as much as
possible. When a hand inserted part has potential for misplacement, we
often pay extra for a pokeyoke feature of some sort.
If the orientation does not affect throughput and is an automated
process,
I don't see the need for same orientation as a high priority at all. It
is
certainly something to strive for, but in my environment it is one of
the
first things to throw out the window. Your environment may differ...
BR,
-Chris
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Green, Mike
Sent: Wednesday, February 28, 2007 6:59 PM
To: [log in to unmask]
Subject: [TN] Component Orientation Survey
When you design boards, do you:
-lay out similar polar components oriented in the same direction for
ease of manufacture regardless of the shortest routing
or
-lay out each component oriented in the best position for routing
regardless of the orientation of other similar parts?
We have a difference of opinion as to which is more prevalent practice.
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