Any significance to the shape of the solder pads on a PCB?

N

Nelson

Guest
I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one. Is
there any significance to that?

--
Nelson
 
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?
Click to expand...

Perhaps it indicates the polarity of diodes, LEDs, etc.
 
Back when I worked with Tango (jurassic era) the pins had a name to match up with the pads in PCB. For non-polar components like resistors the pads were A and B. All the through hole footprints had 1 square terminal. The schematic component had the same name for the pins to match up with the pad name. Failing name matching would cause a net list error and you want NO net errors if you expect it to work.

G˛
 
I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
Click to expand...

Commonly a "pin 1" designation, entered as part of the "footprint"
artwork for the part in whatever PCB-design package was used to do
the layout. You'll almost always see these used on IC footprint
patterns (the through-hole ones at least). I imagine that in
commercial PCB design packages, it's usually a convention to
identify Pin 1 in any footprint where it's practical, since these
footprints may be used both for polarized and non-polarized
components.
 
On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!
Click to expand...

Paul
 
On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article <kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul
Click to expand...

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.

--
Nelson
 
On 8/21/2013 2:27 PM, Nelson wrote:
On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article<kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.
Click to expand...
I thought you were referring to the silk screen art work. Are you saying
you took all the components off the board and sucked the solder out of
the holes so you can now see that some holes were drilled and some were
punched with a square punch?

A properly soldered board will not show any hole if they are
plated-through holes.

Paul
 
"Paul Drahn" wrote in message news:kv3h16$bab$1@dont-email.me...

I thought you were referring to the silk screen art work. Are you
saying you took all the components off the board and sucked the
solder out of the holes so you can now see that some holes were
drilled and some were punched with a square punch?
Click to expand...

He's referring to the shape of the metal pad, not the hole.
 
On Wed, 21 Aug 2013 17:27:10 -0400, Nelson wrote
(in article <0001HW.CE3AA8EE011F018FB02919BF@news.astraweb.com>):

On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article <kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.
Click to expand...

Well, maybe not all the resistors, but quite a few of them. Here's a
photo:

http://www.deejr.net/pbp/2013/08/21/PowerBoardFront.jpg

--
Nelson
 
On 08/21/2013 5:46 PM, Nelson wrote:
On Wed, 21 Aug 2013 17:27:10 -0400, Nelson wrote
(in article <0001HW.CE3AA8EE011F018FB02919BF@news.astraweb.com>):

On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article <kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.



Well, maybe not all the resistors, but quite a few of them. Here's a
photo:

http://www.deejr.net/pbp/2013/08/21/PowerBoardFront.jpg
Click to expand...

Those square holes are for the ground plane end of the resistor (and
other similar parts). This is so the solder will wet properly and thus
connect the leg of the device to the feedthrough hole. The feedthrough
hole is separated from the copper plane mass except for four corners
otherwise the copper plane will sink too much of the heat. More
important on boards that are hand soldered instead of wave-soldered...

John :-#)#



--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
On Thu, 22 Aug 2013 00:55:54 -0400, John Robertson wrote
(in article <JdOdnc5gOJ9HBIjPnZ2dnUVZ_jOdnZ2d@giganews.com>):

On 08/21/2013 5:46 PM, Nelson wrote:
On Wed, 21 Aug 2013 17:27:10 -0400, Nelson wrote
(in article <0001HW.CE3AA8EE011F018FB02919BF@news.astraweb.com>):

On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article <kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.



Well, maybe not all the resistors, but quite a few of them. Here's a
photo:

http://www.deejr.net/pbp/2013/08/21/PowerBoardFront.jpg


Those square holes are for the ground plane end of the resistor (and
other similar parts). This is so the solder will wet properly and thus
connect the leg of the device to the feedthrough hole. The feedthrough
hole is separated from the copper plane mass except for four corners
otherwise the copper plane will sink too much of the heat. More
important on boards that are hand soldered instead of wave-soldered...

John :-#)#
Click to expand...

Thanks! I'm having a hard time visualizing this, however. I have
researched "thermal relief" which is what I think you are referring to
but I can't find any discussion of square pads contacting only at the
corners. In particular, in this case, the ground plane or "copper
flow" appears to be an interior layer. I can't visualize how the
through holes connect to this or pass through without connecting.

Here is an image of the back of the board showing the embedded ground
plane:

http://www.deejr.net/pbp/2013/08/22/PowerBoardBack.jpg

As you can see there are quite a few square pads which don't appear to
connect to the ground plane.


--
Nelson
 
On 08/22/2013 4:48 AM, Nelson wrote:
On Thu, 22 Aug 2013 00:55:54 -0400, John Robertson wrote
(in article <JdOdnc5gOJ9HBIjPnZ2dnUVZ_jOdnZ2d@giganews.com>):

On 08/21/2013 5:46 PM, Nelson wrote:
On Wed, 21 Aug 2013 17:27:10 -0400, Nelson wrote
(in article <0001HW.CE3AA8EE011F018FB02919BF@news.astraweb.com>):

On Wed, 21 Aug 2013 15:54:13 -0400, Paul Drahn wrote
(in article <kv35t8$98n$1@dont-email.me>):

On 8/21/2013 12:02 PM, William Sommerwerck wrote:
"Nelson" wrote in message
news:0001HW.CE3A82C6011701D6B01029BF@news.astraweb.com...

I am trying to create a schematic from a PCB and I notice each
component has one square solder pad hole and one circular one.
Is there any significance to that?

Perhaps it indicates the polarity of diodes, LEDs, etc.
100% correct!

Paul

But all the resistors are that way too :) The board appears to have a
plane sandwiched between the top and bottom. I'm guessing it is either
a ground plane or a V+ plane. I thought maybe one or the other
indicated a plated through hole that connected to the mid plane.



Well, maybe not all the resistors, but quite a few of them. Here's a
photo:

http://www.deejr.net/pbp/2013/08/21/PowerBoardFront.jpg


Those square holes are for the ground plane end of the resistor (and
other similar parts). This is so the solder will wet properly and thus
connect the leg of the device to the feedthrough hole. The feedthrough
hole is separated from the copper plane mass except for four corners
otherwise the copper plane will sink too much of the heat. More
important on boards that are hand soldered instead of wave-soldered...

John :-#)#

Thanks! I'm having a hard time visualizing this, however. I have
researched "thermal relief" which is what I think you are referring to
but I can't find any discussion of square pads contacting only at the
corners. In particular, in this case, the ground plane or "copper
flow" appears to be an interior layer. I can't visualize how the
through holes connect to this or pass through without connecting.

Here is an image of the back of the board showing the embedded ground
plane:

http://www.deejr.net/pbp/2013/08/22/PowerBoardBack.jpg

As you can see there are quite a few square pads which don't appear to
connect to the ground plane.
Click to expand...

It may then be an artifact of the PCB CAD software - the first pin of a
series (2 is a series in this case) is always square. I like the thermal
relief term (thanks!) and for some parts it is probably still valid.

John :-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
SIL patterns invariably have one end with a square solder pad. This just helps you recognize which end is which when you turn your board over. I don't think it has a functional significance.
 
On 9/23/2017 8:16 AM, ss.chelsc@gmail.com wrote:
> SIL patterns invariably have one end with a square solder pad.

The square pad is simply identification.
Pin-1, Cathode, (+) etc.



--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
 
On Saturday, 23 September 2017 14:16:52 UTC+1, ss.c...@gmail.com wrote:
> SIL patterns invariably have one end with a square solder pad. This just helps you recognize which end is which when you turn your board over. I don't think it has a functional significance.

We never used that convention. They were either all square or all rounded.


NT
 
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