panel_via_size.cpp

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 1992-2021 Kicad Developers, see AUTHORS.txt for contributors.
 *
 * 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 3
 * 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, see <http://www.gnu.org/licenses/>.
 */

/* All calculations are based on this [1] online calculator:
 *
 * References:
 *
 * [1]: The CircuitCalculator.com Blog - PCB Via Calculator
 * http://circuitcalculator.com/wordpress/2006/03/12/pcb-via-calculator/
 *
 * [2]: Constructing Your Power Supply - Layout Considerations
 * https://www.ti.com/seclit/ml/slup230/slup230.pdf
 *
 * [3]: Current Carrying Capacity of Vias - Some Conceptual Observations
 * https://www.ultracad.com/articles/viacurrents.pdf
 *
 * [4]: IPC-2221A - Generic Standard on Printed Board Design
 * http://www.sphere.bc.ca/class/downloads/ipc_2221a-pcb%20standards.pdf
 *
 * [5]: Copper - online catalogue source - Goodfellow
 * http://www.goodfellow.com/E/Copper.html
 *
 * [6]: Thermal Conductivity of Metals, Metallic Elements and Alloys
 * https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
 *
 * [7]: Johnson & Graham, High Speed Digital Design: A Handbook of Black Magic
 */

#include <cmath>
#include <wx/choicdlg.h>

#include <bitmaps.h>
#include <calculator_panels/panel_via_size.h>
#include <common_data.h>
#include <pcb_calculator_settings.h>
#include <units_scales.h>


extern double DoubleFromString( const wxString& TextValue );


PANEL_VIA_SIZE::PANEL_VIA_SIZE( wxWindow* parent, wxWindowID id,
 const wxPoint& pos, const wxSize& size,
 long style, const wxString& name ) :
 PANEL_VIA_SIZE_BASE( parent, id, pos, size, style, name )
{
 m_viaResistivityUnits->SetLabel( wxT( "Ω⋅m" ) );
 m_viaTempUnits->SetLabel( wxT( "°C" ) );
 m_viaResUnits->SetLabel( wxT( "Ω" ) );
 m_viaThermalResUnits->SetLabel( wxT( "°C/W" ) );
 m_viaReactanceUnits->SetLabel( wxT( "Ω" ) );

 m_viaBitmap->SetBitmap( KiBitmap( BITMAPS::viacalc ) );

 // Needed on wxWidgets 3.0 to ensure sizers are correctly set
 GetSizer()->SetSizeHints( this );
}


PANEL_VIA_SIZE::~PANEL_VIA_SIZE()
{
}


void PANEL_VIA_SIZE::ThemeChanged()
{
 m_viaBitmap->SetBitmap( KiBitmap( BITMAPS::viacalc ) );
}


void PANEL_VIA_SIZE::OnViaEpsilonR_Button( wxCommandEvent& event )
{
 //Shows a list of current relative dielectric constant(Er) and select a value.
 wxArrayString list = StandardRelativeDielectricConstantList();

 wxString value = wxGetSingleChoice( wxEmptyString, _("Relative Dielectric Constants"),
 list).BeforeFirst( ' ' );

 if( !value.IsEmpty() )
 m_textCtrlPlatingPermittivity->SetValue( value );
}


void PANEL_VIA_SIZE::OnViaRho_Button( wxCommandEvent& event )
{
 wxArrayString list = StandardResistivityList();

 // Shows a list of current Specific resistance list (rho) and select a value
 wxString value = wxGetSingleChoice( wxEmptyString, _( "Electrical Resistivity in Ohm*m" ),
 list ).BeforeFirst( ' ' );

 if( !value.IsEmpty() )
 m_textCtrlPlatingResistivity->SetValue( value );
}


void PANEL_VIA_SIZE::onUpdateViaCalcErrorText( wxUpdateUIEvent& event )
{
 // Update the Error message if a via has a external diameter
 // bigger than the clearance area diameter
 // (therefore the via is inside a copper zone and some parameters cannot be calculated)
 double clearanceDia = std::abs( DoubleFromString( m_textCtrlClearanceDia->GetValue() ) );
 clearanceDia *= m_choiceClearanceDia->GetUnitScale();
 double padDia = std::abs( DoubleFromString( m_textCtrlViaPadDia->GetValue() ) );
 padDia *= m_choiceViaPadDia->GetUnitScale();

 m_staticTextWarning->Show( clearanceDia <= padDia );
}


void PANEL_VIA_SIZE::OnViaResetButtonClick( wxCommandEvent& event )
{
 #define DEFAULT_UNIT_SEL_MM 0
 #define DEFAULT_UNIT_SEL_OHM 0

 m_textCtrlHoleDia->SetValue( wxString::Format( "%g", 0.4 ) );
 m_choiceHoleDia->SetSelection( DEFAULT_UNIT_SEL_MM );
 m_textCtrlPlatingThickness->SetValue( wxString::Format( "%g", 0.035 ) );
 m_choicePlatingThickness->SetSelection( DEFAULT_UNIT_SEL_MM );
 m_textCtrlViaLength->SetValue( wxString::Format( "%g", 1.6 ) );
 m_choiceViaLength->SetSelection( DEFAULT_UNIT_SEL_MM );
 m_textCtrlViaPadDia->SetValue( wxString::Format( "%g", 0.6 ) );
 m_choiceViaPadDia->SetSelection( DEFAULT_UNIT_SEL_MM );
 m_textCtrlClearanceDia->SetValue( wxString::Format( "%g", 1.0 ) );
 m_choiceClearanceDia->SetSelection( DEFAULT_UNIT_SEL_MM );
 m_textCtrlImpedance->SetValue( wxString::Format( "%g", 50.0 ) );
 m_choiceImpedance->SetSelection( DEFAULT_UNIT_SEL_OHM );
 m_textCtrlAppliedCurrent->SetValue( wxString::Format( "%g", 1.0 ) );
 m_textCtrlPlatingResistivity->SetValue( wxString::Format( "%g", 1.72e-8 ) );
 m_textCtrlPlatingPermittivity->SetValue( wxString::Format( "%g", 4.5 ) );
 m_textCtrlTemperatureDiff->SetValue( wxString::Format( "%g", 10.0 ) );
 m_textCtrlRiseTime->SetValue( wxString::Format( "%g", 1.0 ) );
}


void PANEL_VIA_SIZE::LoadSettings( PCB_CALCULATOR_SETTINGS* aCfg )
{
 m_textCtrlHoleDia->SetValue( aCfg->m_ViaSize.hole_diameter );
 m_choiceHoleDia->SetSelection( aCfg->m_ViaSize.hole_diameter_units );

 m_textCtrlPlatingThickness->SetValue( aCfg->m_ViaSize.thickness );
 m_choicePlatingThickness->SetSelection( aCfg->m_ViaSize.thickness_units );

 m_textCtrlViaLength->SetValue( aCfg->m_ViaSize.length );
 m_choiceViaLength->SetSelection( aCfg->m_ViaSize.length_units );

 m_textCtrlViaPadDia->SetValue( aCfg->m_ViaSize.pad_diameter );
 m_choiceViaPadDia->SetSelection( aCfg->m_ViaSize.pad_diameter_units );

 m_textCtrlClearanceDia->SetValue( aCfg->m_ViaSize.clearance_diameter );
 m_choiceClearanceDia->SetSelection( aCfg->m_ViaSize.clearance_diameter_units );

 m_textCtrlImpedance->SetValue( aCfg->m_ViaSize.characteristic_impedance );
 m_choiceImpedance->SetSelection( aCfg->m_ViaSize.characteristic_impedance_units );

 m_textCtrlAppliedCurrent->SetValue( aCfg->m_ViaSize.applied_current );
 m_textCtrlPlatingResistivity->SetValue( aCfg->m_ViaSize.plating_resistivity );
 m_textCtrlPlatingPermittivity->SetValue( aCfg->m_ViaSize.permittivity );
 m_textCtrlTemperatureDiff->SetValue( aCfg->m_ViaSize.temp_rise );
 m_textCtrlRiseTime->SetValue( aCfg->m_ViaSize.pulse_rise_time );
}


void PANEL_VIA_SIZE::SaveSettings( PCB_CALCULATOR_SETTINGS* aCfg )
{
 aCfg->m_ViaSize.hole_diameter = m_textCtrlHoleDia->GetValue();
 aCfg->m_ViaSize.hole_diameter_units = m_choiceHoleDia->GetSelection();
 aCfg->m_ViaSize.thickness = m_textCtrlPlatingThickness->GetValue();
 aCfg->m_ViaSize.thickness_units = m_choicePlatingThickness->GetSelection();
 aCfg->m_ViaSize.length = m_textCtrlViaLength->GetValue();
 aCfg->m_ViaSize.length_units = m_choiceViaLength->GetSelection();
 aCfg->m_ViaSize.pad_diameter = m_textCtrlViaPadDia->GetValue();
 aCfg->m_ViaSize.pad_diameter_units = m_choiceViaPadDia->GetSelection();
 aCfg->m_ViaSize.clearance_diameter = m_textCtrlClearanceDia->GetValue();
 aCfg->m_ViaSize.clearance_diameter_units = m_choiceClearanceDia->GetSelection();
 aCfg->m_ViaSize.characteristic_impedance = m_textCtrlImpedance->GetValue();
 aCfg->m_ViaSize.characteristic_impedance_units = m_choiceImpedance->GetSelection();
 aCfg->m_ViaSize.applied_current = m_textCtrlAppliedCurrent->GetValue();
 aCfg->m_ViaSize.plating_resistivity = m_textCtrlPlatingResistivity->GetValue();
 aCfg->m_ViaSize.permittivity = m_textCtrlPlatingPermittivity->GetValue();
 aCfg->m_ViaSize.temp_rise = m_textCtrlTemperatureDiff->GetValue();
 aCfg->m_ViaSize.pulse_rise_time = m_textCtrlRiseTime->GetValue();
}


void PANEL_VIA_SIZE::OnViaCalculate( wxCommandEvent& event )
{
 // Load parameters
 double finishedHoleDia = std::abs( DoubleFromString( m_textCtrlHoleDia->GetValue() ) );
 double platingThickness = std::abs( DoubleFromString( m_textCtrlPlatingThickness->GetValue() ) );
 double viaLength = std::abs( DoubleFromString( m_textCtrlViaLength->GetValue() ) );
 double padDia = std::abs( DoubleFromString( m_textCtrlViaPadDia->GetValue() ) );
 double clearanceDia = std::abs( DoubleFromString( m_textCtrlClearanceDia->GetValue() ) );
 double charImpedance = std::abs( DoubleFromString( m_textCtrlImpedance->GetValue() ) );
 double appliedCurrent = std::abs( DoubleFromString( m_textCtrlAppliedCurrent->GetValue() ) );
 double platingResistivity = std::abs( DoubleFromString( m_textCtrlPlatingResistivity->GetValue() ) );
 double relativePermitivity = std::abs( DoubleFromString( m_textCtrlPlatingPermittivity->GetValue() ) );
 double temperatureDiff = std::abs( DoubleFromString( m_textCtrlTemperatureDiff->GetValue() ) );
 double pulseRiseTime = std::abs( DoubleFromString( m_textCtrlRiseTime->GetValue() ) );

 // Normalize units
 finishedHoleDia *= m_choiceHoleDia->GetUnitScale();
 platingThickness *= m_choicePlatingThickness->GetUnitScale();
 viaLength *= m_choiceViaLength->GetUnitScale();
 padDia *= m_choiceViaPadDia->GetUnitScale();
 clearanceDia *= m_choiceClearanceDia->GetUnitScale();
 charImpedance *= m_choiceImpedance->GetUnitScale();
 // platingResistivity is ok: it is in Ohm*m in tables

 // Calculate cross-sectional area of the via's cylindrical structure [3]
 double area = M_PI * (finishedHoleDia + platingThickness) * platingThickness; // m^2

 double viaResistance = platingResistivity * viaLength / area; // Ohms

 // Using thermal resistivity value 2.49e-3 meter-Kelvin/Watt, equivalent to
 // thermal conductivity of 401 Watt/(meter-Kelvin) [5][6]
 const double thermalResistivity = 2.49e-3; // m K/W
 double thermalResistance = thermalResistivity * viaLength / area; // deg C/W

 double voltageDrop = appliedCurrent * viaResistance;

 double powerLoss = appliedCurrent * voltageDrop;

 // Estimate current carrying capacity of the via
 // See comment #17 in [1] for a brief discussion on the formula
 // This formula from IPC-2221 [4] is also used in the Track Width calculator
 area /= pow( UNIT_MIL, 2 ); // m^2 to mil^2
 const double k = 0.048;
 const double b = 0.44;
 const double c = 0.725;
 double estimatedAmpacity = k * pow( temperatureDiff, b ) * pow( area, c );

 // Equation 7.6 in [7]
 double capacitance = 55.51 * relativePermitivity * viaLength * padDia;
 capacitance /= clearanceDia - padDia;

 // Equation 7.8 in [7]
 double timeDegradation = 2.2 * capacitance * charImpedance / 2;

 // Equation 7.9 in [7]
 double inductance = 200 * viaLength;
 inductance *= log( 4 * viaLength / finishedHoleDia ) + 1;

 // Equation 7.11 in [7]
 double reactance = M_PI * inductance / pulseRiseTime;

 // Update the display
 VSDisplayValues( viaResistance, voltageDrop, powerLoss, estimatedAmpacity,
 thermalResistance, capacitance, timeDegradation, inductance, reactance );
}

void PANEL_VIA_SIZE::VSDisplayValues( double aViaResistance, double aVoltageDrop, double aPowerLoss,
 double aEstimatedAmpacity, double aThermalResistance,
 double aCapacitance, double aTimeDegradation, double aInductance,
 double aReactance )
{
 wxString msg;

 msg.Printf( "%g", aViaResistance );
 m_ViaResistance->SetLabel( msg );

 msg.Printf( "%g", aVoltageDrop );
 m_ViaVoltageDrop->SetLabel( msg );

 msg.Printf( "%g", aPowerLoss );
 m_ViaPowerLoss->SetLabel( msg );

 msg.Printf( "%g", aEstimatedAmpacity );
 m_ViaAmpacity->SetLabel( msg );

 msg.Printf( "%g", aThermalResistance );
 m_ViaThermalResistance->SetLabel( msg );

 msg.Printf( "%g", aCapacitance );
 m_ViaCapacitance->SetLabel( msg );

 msg.Printf( "%g", aTimeDegradation );
 m_RiseTimeOutput->SetLabel( msg );

 msg.Printf( "%g", aInductance );
 m_Inductance->SetLabel( msg );

 msg.Printf( "%g", aReactance );
 m_Reactance->SetLabel( msg );
}