276 lines
12 KiB
C++
276 lines
12 KiB
C++
/*
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* This program source code file is part of KICAD, a free EDA CAD application.
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*
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* Copyright (C) 1992-2019 Kicad Developers, see AUTHORS.txt for contributors.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 3
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/* All calculations are based on this [1] online calculator:
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*
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* References:
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*
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* [1]: The CircuitCalculator.com Blog - PCB Via Calculator
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* http://circuitcalculator.com/wordpress/2006/03/12/pcb-via-calculator/
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*
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* [2]: Constructing Your Power Supply - Layout Considerations
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* https://www.ti.com/seclit/ml/slup230/slup230.pdf
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*
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* [3]: Current Carrying Capacity of Vias - Some Conceptual Observations
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* https://www.ultracad.com/articles/viacurrents.pdf
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*
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* [4]: IPC-2221A - Generic Standard on Printed Board Design
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* http://www.sphere.bc.ca/class/downloads/ipc_2221a-pcb%20standards.pdf
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*
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* [5]: Copper - online catalogue source - Goodfellow
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* http://www.goodfellow.com/E/Copper.html
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*
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* [6]: Thermal Conductivity of Metals, Metallic Elements and Alloys
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* https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
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*
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* [7]: Johnson & Graham, High Speed Digital Design: A Handbook of Black Magic
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*/
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#include <cmath>
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#include <wx/wx.h>
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#include <wx/config.h>
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#include <pcb_calculator_frame_base.h>
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#include <pcb_calculator.h>
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#include <UnitSelector.h>
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#include <units_scales.h>
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#include <common_data.h>
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extern double DoubleFromString( const wxString& TextValue );
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// Key words to read/write some parameters in config:
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#define KEYWORD_VS_HOLE_DIA wxT( "VS_Hole_Dia" )
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#define KEYWORD_VS_HOLE_DIA_UNIT wxT( "VS_Hole_Dia_Unit" )
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#define KEYWORD_VS_THICKNESS wxT( "VS_Plating_Thickness" )
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#define KEYWORD_VS_THICKNESS_UNIT wxT( "VS_Plating_Thickness_Unit" )
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#define KEYWORD_VS_LENGTH wxT( "VS_Via_Length" )
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#define KEYWORD_VS_LENGTH_UNIT wxT( "VS_Via_Length_Unit" )
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#define KEYWORD_VS_PAD_DIA wxT( "VS_Pad_Dia" )
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#define KEYWORD_VS_PAD_DIA_UNIT wxT( "VS_Pad_Dia_Unit" )
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#define KEYWORD_VS_CLEARANCE_DIA wxT( "VS_Clearance_Dia" )
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#define KEYWORD_VS_CLEARANCE_DIA_UNIT wxT( "VS_Clearance_Dia_Unit" )
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#define KEYWORD_VS_CH_IMPEDANCE wxT( "VS_Characteristic_Impedance" )
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#define KEYWORD_VS_CH_IMPEDANCE_UNIT wxT( "VS_Characteristic_Impedance_Unit" )
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#define KEYWORD_VS_CURRENT wxT( "VS_Current" )
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#define KEYWORD_VS_RESISTIVITY wxT( "VS_Resistivity" )
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#define KEYWORD_VS_PERMITTIVITY wxT( "VS_Permittivity" )
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#define KEYWORD_VS_TEMP_DIFF wxT( "VS_Temperature_Differential" )
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#define KEYWORD_VS_PULSE_RISE_TIME wxT( "VS_Pulse_Rise_Time" )
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/**
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* Shows a list of current relative dielectric constant(Er)
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* and set the selected value in main dialog frame
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*/
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void PCB_CALCULATOR_FRAME::OnViaEpsilonR_Button( wxCommandEvent& event )
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{
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wxArrayString list = StandardRelativeDielectricConstantList();
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wxString value = wxGetSingleChoice( wxEmptyString,
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_("Relative Dielectric Constants"), list).BeforeFirst( ' ' );
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if( ! value.IsEmpty() )
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m_textCtrlPlatingPermittivity->SetValue( value );
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}
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/**
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* Shows a list of current Specific resistance list (rho)
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* and set the selected value in main dialog frame
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*/
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void PCB_CALCULATOR_FRAME::OnViaRho_Button( wxCommandEvent& event )
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{
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wxArrayString list = StandardResistivityList();
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wxString value = wxGetSingleChoice( wxEmptyString,
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_("Specific Resistance"), list).BeforeFirst( ' ' );
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if( ! value.IsEmpty() )
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m_textCtrlPlatingResistivity->SetValue( value );
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}
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void PCB_CALCULATOR_FRAME::VS_Init( wxConfigBase* aCfg )
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{
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int tmp;
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wxString msg;
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#define DEFAULT_UNIT_SEL_MM 0
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// Read parameter values
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aCfg->Read( KEYWORD_VS_HOLE_DIA, &msg, wxT( "0.4" ) );
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m_textCtrlHoleDia->SetValue( msg );
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aCfg->Read( KEYWORD_VS_HOLE_DIA_UNIT, &tmp, DEFAULT_UNIT_SEL_MM );
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m_choiceHoleDia->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_THICKNESS, &msg, wxT( "0.035" ) );
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m_textCtrlPlatingThickness->SetValue( msg );
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aCfg->Read( KEYWORD_VS_THICKNESS_UNIT, &tmp, DEFAULT_UNIT_SEL_MM );
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m_choicePlatingThickness->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_LENGTH, &msg, wxT( "1.6" ) );
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m_textCtrlViaLength->SetValue( msg );
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aCfg->Read( KEYWORD_VS_LENGTH_UNIT, &tmp, DEFAULT_UNIT_SEL_MM );
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m_choiceViaLength->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_PAD_DIA, &msg, wxT( "0.6" ) );
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m_textCtrlViaPadDia->SetValue( msg );
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aCfg->Read( KEYWORD_VS_PAD_DIA_UNIT, &tmp, DEFAULT_UNIT_SEL_MM );
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m_choiceViaPadDia->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_CLEARANCE_DIA, &msg, wxT( "1.0" ) );
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m_textCtrlClearanceDia->SetValue( msg );
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aCfg->Read( KEYWORD_VS_CLEARANCE_DIA_UNIT, &tmp, DEFAULT_UNIT_SEL_MM );
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m_choiceClearanceDia->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_CH_IMPEDANCE, &msg, wxT( "50" ) );
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m_textCtrlImpedance->SetValue( msg );
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aCfg->Read( KEYWORD_VS_CH_IMPEDANCE_UNIT , &tmp, DEFAULT_UNIT_SEL_MM );
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m_choiceImpedance->SetSelection( tmp );
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aCfg->Read( KEYWORD_VS_CURRENT, &msg, wxT( "1" ) );
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m_textCtrlAppliedCurrent->SetValue( msg );
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aCfg->Read( KEYWORD_VS_RESISTIVITY, &msg, wxT( "1.72e-8" ) );
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m_textCtrlPlatingResistivity->SetValue( msg );
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aCfg->Read( KEYWORD_VS_PERMITTIVITY, &msg, wxT( "4.5" ) );
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m_textCtrlPlatingPermittivity->SetValue( msg );
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aCfg->Read( KEYWORD_VS_TEMP_DIFF, &msg, wxT( "10" ) );
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m_textCtrlTemperatureDiff->SetValue( msg );
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aCfg->Read( KEYWORD_VS_PULSE_RISE_TIME, &msg, wxT( "1" ) );
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m_textCtrlRiseTime->SetValue( msg );
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}
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void PCB_CALCULATOR_FRAME::VS_WriteConfig( wxConfigBase* aCfg )
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{
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// Save current parameters values in config
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aCfg->Write( KEYWORD_VS_HOLE_DIA, m_textCtrlHoleDia->GetValue() );
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aCfg->Write( KEYWORD_VS_HOLE_DIA_UNIT, m_choiceHoleDia->GetSelection() );
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aCfg->Write( KEYWORD_VS_THICKNESS, m_textCtrlPlatingThickness->GetValue() );
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aCfg->Write( KEYWORD_VS_THICKNESS_UNIT, m_choicePlatingThickness->GetSelection() );
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aCfg->Write( KEYWORD_VS_LENGTH, m_textCtrlViaLength->GetValue() );
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aCfg->Write( KEYWORD_VS_LENGTH_UNIT, m_choiceViaLength->GetSelection() );
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aCfg->Write( KEYWORD_VS_PAD_DIA, m_textCtrlViaPadDia->GetValue() );
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aCfg->Write( KEYWORD_VS_PAD_DIA_UNIT, m_choiceViaPadDia->GetSelection() );
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aCfg->Write( KEYWORD_VS_CLEARANCE_DIA, m_textCtrlClearanceDia->GetValue() );
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aCfg->Write( KEYWORD_VS_CLEARANCE_DIA_UNIT, m_choiceClearanceDia->GetSelection() );
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aCfg->Write( KEYWORD_VS_CH_IMPEDANCE, m_textCtrlImpedance->GetValue() );
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aCfg->Write( KEYWORD_VS_CH_IMPEDANCE_UNIT, m_choiceImpedance->GetSelection() );
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aCfg->Write( KEYWORD_VS_CURRENT, m_textCtrlAppliedCurrent->GetValue() );
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aCfg->Write( KEYWORD_VS_RESISTIVITY, m_textCtrlPlatingResistivity->GetValue() );
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aCfg->Write( KEYWORD_VS_PERMITTIVITY, m_textCtrlPlatingPermittivity->GetValue() );
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aCfg->Write( KEYWORD_VS_TEMP_DIFF, m_textCtrlTemperatureDiff->GetValue() );
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aCfg->Write( KEYWORD_VS_PULSE_RISE_TIME, m_textCtrlRiseTime->GetValue() );
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}
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void PCB_CALCULATOR_FRAME::OnViaCalculate( wxCommandEvent& event )
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{
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// Load parameters
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double finishedHoleDia = std::abs( DoubleFromString( m_textCtrlHoleDia->GetValue() ) );
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double platingThickness = std::abs( DoubleFromString( m_textCtrlPlatingThickness->GetValue() ) );
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double viaLength = std::abs( DoubleFromString( m_textCtrlViaLength->GetValue() ) );
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double padDia = std::abs( DoubleFromString( m_textCtrlViaPadDia->GetValue() ) );
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double clearanceDia = std::abs( DoubleFromString( m_textCtrlClearanceDia->GetValue() ) );
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double charImpedance = std::abs( DoubleFromString( m_textCtrlImpedance->GetValue() ) );
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double appliedCurrent = std::abs( DoubleFromString( m_textCtrlAppliedCurrent->GetValue() ) );
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double platingResistivity = std::abs( DoubleFromString( m_textCtrlPlatingResistivity->GetValue() ) );
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double relativePermitivity = std::abs( DoubleFromString( m_textCtrlPlatingPermittivity->GetValue() ) );
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double temperatureDiff = std::abs( DoubleFromString( m_textCtrlTemperatureDiff->GetValue() ) );
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double pulseRiseTime = std::abs( DoubleFromString( m_textCtrlRiseTime->GetValue() ) );
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// Normalize units
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finishedHoleDia *= m_choiceHoleDia->GetUnitScale();
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platingThickness *= m_choicePlatingThickness->GetUnitScale();
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viaLength *= m_choiceViaLength->GetUnitScale();
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padDia *= m_choiceViaPadDia->GetUnitScale();
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clearanceDia *= m_choiceClearanceDia->GetUnitScale();
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charImpedance *= m_choiceImpedance->GetUnitScale();
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platingResistivity = platingResistivity / 100; // Ohm-cm to Ohm-m
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// Calculate cross-sectional area of the via's cylindrical structure [3]
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double area = M_PI * (finishedHoleDia + platingThickness) * platingThickness; // m^2
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double viaResistance = platingResistivity * viaLength / area; // Ohms
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// Using thermal resistivity value 2.49e-3 meter-Kelvin/Watt, equivalent to
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// thermal conductivity of 401 Watt/(meter-Kelvin) [5][6]
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const double thermalResistivity = 2.49e-3; // m K/W
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double thermalResistance = thermalResistivity * viaLength / area; // deg C/W
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double voltageDrop = appliedCurrent * viaResistance;
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double powerLoss = appliedCurrent * voltageDrop;
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// Estimate current carrying capacity of the via
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// See comment #17 in [1] for a brief discussion on the formula
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// This formula from IPC-2221 [4] is also used in the Track Width calculator
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area /= pow( UNIT_MIL, 2 ); // m^2 to mil^2
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const double k = 0.048;
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const double b = 0.44;
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const double c = 0.725;
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double estimatedAmpacity = k * pow( temperatureDiff, b ) * pow( area, c );
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// Equation 7.6 in [7]
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double capacitance = 55.51 * relativePermitivity * viaLength * padDia;
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capacitance /= clearanceDia - padDia;
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// Equation 7.8 in [7]
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double timeDegradation = 2.2 * capacitance * charImpedance / 2;
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// Equation 7.9 in [7]
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double inductance = 200 * viaLength;
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inductance *= log( 4 * viaLength / finishedHoleDia ) + 1;
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// Equation 7.11 in [7]
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double reactance = M_PI * inductance / pulseRiseTime;
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// Update the display
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VSDisplayValues( viaResistance, voltageDrop, powerLoss, estimatedAmpacity,
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thermalResistance, capacitance, timeDegradation, inductance, reactance );
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}
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void PCB_CALCULATOR_FRAME::VSDisplayValues( double aViaResistance, double aVoltageDrop,
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double aPowerLoss, double aEstimatedAmpacity, double aThermalResistance,
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double aCapacitance, double aTimeDegradation, double aInductance, double aReactance )
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{
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wxString msg;
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msg.Printf( "%g", aViaResistance );
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m_ViaResistance->SetLabel( msg );
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msg.Printf( "%g", aVoltageDrop );
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m_ViaVoltageDrop->SetLabel( msg );
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msg.Printf( "%g", aPowerLoss );
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m_ViaPowerLoss->SetLabel( msg );
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msg.Printf( "%g", aEstimatedAmpacity );
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m_ViaAmpacity->SetLabel( msg );
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msg.Printf( "%g", aThermalResistance );
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m_ViaThermalResistance->SetLabel( msg );
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msg.Printf( "%g", aCapacitance );
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m_ViaCapacitance->SetLabel( msg );
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msg.Printf( "%g", aTimeDegradation );
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m_RiseTimeOutput->SetLabel( msg );
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msg.Printf( "%g", aInductance );
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m_Inductance->SetLabel( msg );
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msg.Printf( "%g", aReactance );
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m_Reactance->SetLabel( msg );
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}
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