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Feature #5078

round all SMD pads

Added by mschramm 7 months ago. Updated 7 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
03/17/2021
Due date:
% Done:

100%


Description

On the current design, all bigger ICs have rounded pads, but none of the smaller ones and also none of the passive parts have.

We prefer rounded pads (and rounded shapes of the respective openings in the solder cream stencil) as they both reduce the probability for solder beads and also reduce the number of stencil cleaning cycles during a production run (amongst other advantages). Of course the solder stop openings shall then adapt to the changed shapes.

Please slightly round all SMD pads which do not have a similar shape already. - While the IPC-7351B recommandation is a full radius pad (adapts to more different solder paste grain sizes, and preferred for tall and long pads like for the huge TQFP), for the simpler parts we prefer a rounded rechtangle over an oblong (see image; anim gif).

For Eagle, I usually start with these setting as a minimum (see 2nd image); maybe you also can automagically adapt it percentaged to the pad's size.

round-shaped.gif View round-shaped.gif 22 KB mschramm, 03/17/2021 12:54 PM
shapes-global.jpg View shapes-global.jpg 10.3 KB mschramm, 03/17/2021 12:58 PM
before.png View before.png 744 KB cibomahto, 03/17/2021 05:36 PM
after.png View after.png 825 KB cibomahto, 03/17/2021 05:36 PM
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History

#1 Updated by cibomahto 7 months ago

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Implemented here: https://github.com/openvizsla/ov_ftdi/pull/46/commits/86f41f925f95d7c2371435c560bed0e16a6bc2a2

  • Change all rectangular pads to rounded rect pads with a 30% corner radius
  • Geometry of pads that were already round are not modified.

Note: This was done directly on the PCB, rather than replacing individual component footprints. If components are added/modified in the future, this may need to be reapplied.

To select the rectangular pads, the following PCB filter was used:

(ObjectKind = 'Pad') And (PadShape_AllLayers = 'Rectangular')

Similarly, to select these pads (for further edits), a similar filter can be used:

(ObjectKind = 'Pad') And (PadShape_AllLayers = 'Rounded Rectangle') And (Pad_CornerRadius_AllLayers = '30%')

#2 Updated by cibomahto 7 months ago

  • Status changed from New to In Progress

#3 Updated by mschramm 7 months ago

  • Category deleted (electronics)
  • Status changed from In Progress to Resolved
  • Assignee deleted (cibomahto)
  • % Done changed from 0 to 100

solved, thanks!

#4 Updated by mschramm 7 months ago

  • Assignee set to cibomahto

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