kicad-developers team mailing list archive

[Mikael Arguedas <mikael.arguedas@xxxxxxxxx>]

Hi guys,

Here is an updated version of this new qfn wizard.
Changes:
 - fixed thermal pad numbering when no subdivision are requested (epad
subdiv x= 0|1 or epad subdiv y =0|1). thanks to Peter Horvath testing.
- set the attribute to SMD
- round the courtyard to land on a 0.05mm grid (this feature relies on the
patch of this thread
<https://lists.launchpad.net/kicad-developers/msg23062.html>)

Could you please let us know if you want to integrate/support wizards for
components having thermal pads? I noticed that Maurice worked on similar
kind of plugins in the past but they have never been merged.

If you do want to integrate them, Peter and I are willing to add several
features to this plugin and it's equivalent for SON footprints "son_wizard"
plugin:
- placing thermal vias centered on the thermal pad array
- add a possibility of "outward extension" of the pad for people willing to
generate HandSoldering version of the footprints

Thanks!
Mikael

On Thu, Feb 11, 2016 at 2:13 PM, Mikael Arguedas <mikael.arguedas@xxxxxxxxx>
wrote:

> Hi,
>
> This patch adds a qfn_wizard.py plugin for footprint generation.
> This is a copy of the qfp_wizard with a few changes allowing to center the
> pads on the package outline and to add an array of exposed pads in the
> center.
>
> I've seen similar works online from several people so I'm not sure if this
> is a feature that you actually want to implement or already rejected in the
> past
>
> Regards,
> Mikael Arguedas
>

=== modified file 'pcbnew/scripting/plugins/PadArray.py'
--- pcbnew/scripting/plugins/PadArray.py	2015-10-31 11:54:48 +0000
+++ pcbnew/scripting/plugins/PadArray.py	2016-02-11 22:01:28 +0000
@@ -169,6 +169,12 @@
                 self.AddPad(pad)
 
 
+class EPADGridArray(PadGridArray):
+
+  def NamingFunction(self, nx, ny):
+    return self.firstPadNum
+
+
 class PadZGridArray(PadArray):
 
     def __init__(self, pad, pad_count, line_count, line_pitch,

=== added file 'pcbnew/scripting/plugins/qfn_wizard.py'
--- pcbnew/scripting/plugins/qfn_wizard.py	1970-01-01 00:00:00 +0000
+++ pcbnew/scripting/plugins/qfn_wizard.py	2016-02-16 23:12:04 +0000
@@ -0,0 +1,161 @@
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+#  MA 02110-1301, USA.
+#
+
+from __future__ import division
+import pcbnew
+
+import HelpfulFootprintWizardPlugin as HFPW
+import PadArray as PA
+
+class QFNWizard(HFPW.HelpfulFootprintWizardPlugin):
+
+    def GetName(self):
+        return "QFN"
+
+    def GetDescription(self):
+        return "Quad Flat No-lead footprint wizard"
+
+    def GenerateParameterList(self):
+        self.AddParam("Pads", "n", self.uNatural, 100)
+        self.AddParam("Pads", "pad pitch", self.uMM, 0.5)
+        self.AddParam("Pads", "pad width", self.uMM, 0.25)
+        self.AddParam("Pads", "pad length", self.uMM, 1.5)
+        self.AddParam("Pads", "oval", self.uBool, True)
+        self.AddParam("Pads", "epad subdiv x", self.uNatural, 2)
+        self.AddParam("Pads", "epad subdiv y", self.uNatural, 2)
+
+        self.AddParam("Package", "package width", self.uMM, 14)
+        self.AddParam("Package", "package height", self.uMM, 14)
+        self.AddParam("Package", "courtyard margin", self.uMM, 1)
+
+    def CheckParameters(self):
+        self.CheckParamInt("Pads", "*n", is_multiple_of=4)
+        self.CheckParamBool("Pads", "*oval")
+
+    def GetValue(self):
+        return "QFN_%d" % self.parameters["Pads"]["*n"]
+
+    def BuildThisFootprint(self):
+        pads = self.parameters["Pads"]
+
+        pad_pitch = pads["pad pitch"]
+        pad_length = pads["pad length"]
+        pad_width = pads["pad width"]
+
+        v_pitch = self.parameters["Package"]["package height"]
+        h_pitch = self.parameters["Package"]["package width"]
+
+        pads_per_row = pads["*n"] // 4
+
+        row_len = (pads_per_row - 1) * pad_pitch
+
+        pad_shape = pcbnew.PAD_SHAPE_OVAL if pads["*oval"] else pcbnew.PAD_SHAPE_RECT
+
+        h_pad = PA.PadMaker(self.module).SMDPad( pad_length, pad_width,
+                                                 shape=pad_shape, rot_degree=90.0)
+        v_pad = PA.PadMaker(self.module).SMDPad( pad_length, pad_width, shape=pad_shape)
+
+        #left row
+        pin1Pos = pcbnew.wxPoint(-h_pitch / 2, 0)
+        array = PA.PadLineArray(h_pad, pads_per_row, pad_pitch, True, pin1Pos)
+        array.SetFirstPadInArray(1)
+        array.AddPadsToModule(self.draw)
+
+        #bottom row
+        pin1Pos = pcbnew.wxPoint(0, v_pitch / 2)
+        array = PA.PadLineArray(v_pad, pads_per_row, pad_pitch, False, pin1Pos)
+        array.SetFirstPadInArray(pads_per_row + 1)
+        array.AddPadsToModule(self.draw)
+
+        #right row
+        pin1Pos = pcbnew.wxPoint(h_pitch / 2, 0)
+        array = PA.PadLineArray(h_pad, pads_per_row, -pad_pitch, True,
+                                pin1Pos)
+        array.SetFirstPadInArray(2*pads_per_row + 1)
+        array.AddPadsToModule(self.draw)
+
+        #top row
+        pin1Pos = pcbnew.wxPoint(0, -v_pitch / 2)
+        array = PA.PadLineArray(v_pad, pads_per_row, -pad_pitch, False,
+                                pin1Pos)
+        array.SetFirstPadInArray(3*pads_per_row + 1)
+        array.AddPadsToModule(self.draw)
+
+        lim_x = self.parameters["Package"]["package width"] / 2
+        lim_y = self.parameters["Package"]["package height"] / 2
+        inner = (row_len / 2) + pad_pitch
+
+        # epad
+        epad_width = self.parameters["Package"]["package height"] - (2*pad_length)
+        epad_length  = self.parameters["Package"]["package width"] - (2*pad_length)
+        epad_subdv_x = pads["*epad subdiv x"]
+        epad_subdv_y = pads["*epad subdiv y"]
+
+        if (epad_subdv_y != 0 and epad_subdv_x != 0) and (epad_subdv_y != 1 or epad_subdv_y != 1):
+          px = pcbnew.FromMM(0.1); py = pcbnew.FromMM(0.1)
+          esubpad_size_x = epad_length / epad_subdv_x - px
+          esubpad_size_y = epad_width / epad_subdv_y - py
+          epad1_pos = pcbnew.wxPoint(-(esubpad_size_x*(epad_subdv_x-1)/2), -esubpad_size_y*(epad_subdv_y-1)/2)
+          epad = PA.PadMaker(self.module).SMDPad( esubpad_size_y, esubpad_size_x,
+                  shape=pcbnew.PAD_SHAPE_RECT, rot_degree=0.0)
+          array = PA.EPADGridArray(epad, epad_subdv_x, epad_subdv_y, esubpad_size_x + px, esubpad_size_y + py, pcbnew.wxPoint(0,0))
+          array.SetFirstPadInArray(pads["*n"]+1)
+          array.AddPadsToModule(self.draw)
+
+        else:
+          epad = PA.PadMaker(self.module).SMDPad(epad_length, epad_width)
+          epad_pos = pcbnew.wxPoint(0,0)
+          array = PA.PadLineArray(epad, 1, 1, False, epad_pos)
+          array.SetFirstPadInArray(pads["*n"]+1)
+          array.AddPadsToModule(self.draw)
+        
+        #top left - diagonal
+        self.draw.Line(-lim_x, -inner, -inner, -lim_y)
+        # top right
+        self.draw.Polyline([(inner, -lim_y), (lim_x, -lim_y), (lim_x, -inner)])
+        # bottom left
+        self.draw.Polyline([(-inner, lim_y), (-lim_x, lim_y), (-lim_x, inner)])
+        # bottom right
+        self.draw.Polyline([(inner, lim_y), (lim_x, lim_y), (lim_x, inner)])
+
+        # Courtyard
+        cmargin = self.parameters["Package"]["courtyard margin"]
+        self.draw.SetLayer(pcbnew.F_CrtYd)
+        sizex = (lim_x + cmargin) * 2 + pad_length/2.
+        sizey = (lim_y + cmargin) * 2 + pad_length/2.
+        # round size to nearest 0.1mm, rectangle will thus land on a 0.05mm grid
+        sizex = self.PutOnGrid(sizex, 0.1)
+        sizey = self.PutOnGrid(sizey, 0.1)
+        # set courtyard line thickness to the one defined in KLC
+        thick = self.draw.GetLineThickness()
+        self.draw.SetLineThickness(pcbnew.FromMM(0.05))
+        self.draw.Box(0, 0, sizex, sizey)
+        # restore line thickness to previous value
+        self.draw.SetLineThickness(pcbnew.FromMM(thick))
+
+        #reference and value
+        text_size = self.GetTextSize()  # IPC nominal
+        text_offset = v_pitch / 2 + text_size + pad_length / 2
+
+        self.draw.Value(0, text_offset, text_size)
+        self.draw.Reference(0, -text_offset, text_size)
+
+        # set SMD attribute
+        self.module.SetAttributes(pcbnew.MOD_CMS)
+
+QFNWizard().register()
+
+