What is this rectangle on a lib SMD pad


#1

HI,
I’m using V5 and trying to understand what I am looking at when I see a pad on the screen. Also how and where changes can be made (globally / locally)

I’ve opened the V5 lib footprint: R_0805_2012Metric

I see:

  1. The inner rectangle with square corners = copper pad

  2. Not shown is the mask which is the same size as 3) below but with square corners.

  3. An outer rectangle with rounded corners. I can’t identify what this represents. At first I thought it was the clearance zone it doesn’t change with changes in clearance.

My Test:
If I run a trace from a non-related net near the SMD pad it will get no closer than the rounded cornered rectangle (0.2mm)
However, If from the Pcbnew tools (setup/DesignRulesEditor/Net Classes editor) I change the minimum pad clearance from 0.2 to 0.5 mm the rectangle with the rounded corners does not change shape but now I can only bring the non-related trace to within 0.5mm

So is the rounded corner rectangle the clearance zone but doesn’t change with clearance or is it something else?

Thanks
John

WIndows 10 /64

Application: kicad
Version: (5.0.0-rc2-dev-694-g787ee62db), release build
Libraries:
wxWidgets 3.0.3
libcurl/7.54.1 OpenSSL/1.0.2l zlib/1.2.11 libssh2/1.8.0 nghttp2/1.23.1 librtmp/2.3
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
wxWidgets: 3.0.3 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.60.0
Curl: 7.54.1
Compiler: GCC 7.1.0 with C++ ABI 1011

Build settings:
USE_WX_GRAPHICS_CONTEXT=OFF
USE_WX_OVERLAY=OFF
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_SPICE=ON


#2

Short answer,
I know it shows the boundary for fill-zones.
And, if you put silkscreen inside this square, OSH Park won’t print that silkscreen element; even if the silkscreen is not over the copper.


#3

Thanks for the OSH Park info. However in today’s version of V5 the fill is limited by some other variable (haven’t looked at the fills yet).

John


#4

Yea, you need to set the fill-zone parameters to the global parameters… sorta.

If you drop the fill-zone settings below the global settings, I think the global will override the zone setting.

You can PM me for the settings I use for OSH Park, as I don’t want to publicly recommend other than they have on their web site.

Like I said, it was the short answer. Once I found out that my silkscreen went away on a purchased board, I just decided to keep everything out and not worry about it.

I’d not bet that someone has a much more technical answer, but me keeping “anything/everything” out of that defined area has resulted in otherwise perfect boards from manufacture.


#5

I think it’s solder mask clearance.


#6

Again, I had silkscreen that was not in either “pad/silk box” outline but was within the outer mentioned box, and that silk did NOT make it onto the board.

I don’t think this feature was ever in the stable version 4; so the details have not been discussed.


#7

SOLVED!

After I change the clearance for the pad (see Setup/Design Rules/Design Rules editor), I changed from the default 0.2mm to 0.5mm the rectangle with the rounded corners did not change until I clicked on it. See the attached screenshot where I clicked on the left pad but not the right pad.

I found even without the graphic changing, the clearance did change to the updated value.

John

Clipboard_Round%20increased%20clearance


#8

Hi John,

Do you have steps to reproduce the clearance line not updating until clicked? It always updates instantly for me.

Thanks,
Jeff.


#9

Hi Jeff,
Thanks for all your efforts :slight_smile:

To help me learn the footprint characteristics I created a test project (I can upload it if it would help but it is really trivial)

  1. A schematic with 2 SMD resistors each connected to itself (aka shorted out).
  2. I pair the footprints in CvPCB. (R_0805_2012Metric) Save and open a Pcbnew.
    I’m in the “mm” mode.
  3. I run a clad from R1 pad 1 to R1 pad 2
  4. I put the canvas in the outline pad mode
  5. With nothing selected I go to Setup/Design Rules
  6. In the Design Rules Editor I change the “Default” “Clearance” from 0.2 to 0.5 --> OK
  7. Back to the PCB, nothing has changed.

If I click on the component both clearance areas change
If I click on the pad only that pad changes. However when I finally click on the other R1 pad (or any other pad) they instantly change.

If I don’t click on any R1 pad but run a trace right near R1 outline, the new clearance is in force (even though the graphic is not).

F3 (redraw) doesn’t change this situation

There is no issue for me now that I know what is going on. I found it the old fashion way (trying every option and check box until I knew what each did and how to control it).

I was thinking of creating a simple graphic of a pad and annotating it with the different characteristics. If there were somewhere to upload it rather than a simple post I might just do that.

Regards
John


#10

Unlike most forums that require external hosting or multiple steps, here you can simply paste (or drag n drop, I think) graphics directly into your post while composing :slight_smile:


#11

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