H eff = H 1 + H 2 2 H e f f = H 1 + H 2 2. Select the box with the geometry that you would like to calculate. Impedance trace widths based on Bittele's standard Stackups. 5mm pitch BGA. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion, copper roughness, phase shift, etc. The Microstrip Impedance Calculator is a vital tool in the design and analysis of microwave circuits. Share. 125; Tolerances; Certifications; RoHS - Lead Free; Electrical Test;. At times, you need to lower the copper weight to achieve a specific impedance. We recommend the software from. It is intended only as a very crude estimate, as I. Dual Stripline Trace. Figure 3 is the plot of impedance versus trace width for the three most common types of transmission lines in PCBs—surface microstrip (SMS); buried microstrip (BMS) and centered stripline (CSL). 72mil. We will also tell you by how much you can expect the temperature of your PCB trace to. per sq. It is likely that the calculated trace width will be a value that cannot be ordered, for example, 0. Where: Z 0 is the characteristic impedance of the microstrip; ε r is the relative permittivity (dielectric constant) of the substrate material; h is the height of the microstrip above the ground plane; W is the width of the microstrip trace; By knowing the values of the dielectric constant, height, and width, you can use this formula to calculate the characteristic. Microstrip Trace: Embedded Microstrip Trace: Stripline Trace: Dual Stripline Trace: Geometric Parameter Definitions. Your stackup affects your trace impedance, and you can take. However, if you select “impedance control” options when getting a quote from a manufacturer, it’s important to know that this will bring additional engineering costs. H 1 H 1 = subtrate height 1. Such a stripline is constructed with two traces referenced to the same reference planes above and below the traces with a dielectric material between them. Broadside Trace Inductance Calculator. Get latest updates and offers. spacing: 0,15mm. Some of its key features are; displays insertion. 1524 mm (OSH Park minimum), and adjust trace width (W) until you get a Zodd of about 45 Ω. The general rule is separation distance should be equal to 3 times the trace width. 68. If you need to use differential pairs, you. The board thicknesses are given in mm so it is not clear that the required units for trace width appear to be mil (0. FR4 Impedance Distortion Calc 5. This tool uses formulas from IPC-2221 to calculate the width of a copper printed circuit board conductor or "trace" required to carry a given current while keeping the resulting increase in trace temperature below a specified limit. Hello ; Considering your post " I am not sure how it's supposed to work " Since JLCPCB produces high precision PCBs then every single parameter should be controlled carefully and that's why we are providing this guide calculator to define what is the trace width and trace space to set in order to maintain a certain impedance value. 3 is the base material PP’s dielectric constant W1=>13. Cite. These calculators will return an impedance value for pairs of trace width, substrate thickness, and copper weight values. 92445. The designer can normally enter their desired impedance, and the calculator will determine the PCB trace width needed to meet that impedance goal. For your convenience, we have designed a Impedance Calculator to help you calculate the impedance and trace width you need. H 2 H 2 = subtrate height 2. 015mm. Controlled differential impedance starts with characteristic impedance. Designing trace width for HDI impedance adjustments. W represents trace width. Reflex Klystron Calculator. Note also that, if you have ground poured on the same layer, that reduces impedance. This model was originally developed by analyzing trace impedance measurements using a regression model. Using typical values of W= 9 mil, H= 24 mil, T = 1. C])^b))^ (1/c) Then, the Width is calculated:. In my layer stack manager, I have the following: Note that Altium calculates that the trace should be ~100 mil wide, which is significantly higher than what the datasheet suggests (0. 17mil is the PP thickness between impedance trace layer and reference layer,it is 0. In a controlled impedance design the designer specifies the impedance rather than the trace width. Find a Location Avnet Americas. Knowing that the test cable and the. The characteristic impedance (Z o) of coplanar waveguide with ground or microstrip lines with signal side ground plane can be calculated using the active calculator or the equations at the bottom of the page. This tool includes an industry-standard field solver that is built into your PCB layer stackup. 8. IPC 6012 CLASS 2. This form of microstrip is composed of two traces. Typ e, V ref and, if needed, I a d j , select the field you want to calculate (one of the resistors or the output voltage) and enter the other two values. Now I'd like to get into this topic and the first task would be to create a ~ 10cm board to board interconnect flex PCB with 90 ohm (USB) and 100 ohm (LVDS) controlled impedance traces on it. Calculations are made using the formula below: Where: Enter the frequency and inductance into the calculator, choose the. For example, with a thickness of 0. 76mm Rogers4350B substrate at a certain frequency and with 35 micron. Gaps in signal traces impact the entire test waveform, and its single-point impedance is too high, making the entire waveform uneven. A coplanar waveguide with groundplane distance H = 1. If the ratio is about 0. A 3D view of a complex impedance controlled PCB in Altium Designer. 0; 1 < εr < 15 ) Select the units for all dimensions: mm mils. Figure 2. 7563 mm (~30 mils). 020. Modeling approximation can be used to understand the impedance of. The required inputs are the Dk value for the dielectric constant of the PCB substrate, and the. 30967mm) is slightly larger the size of the smallest pad (0. There are many factors that go into calculating the width of an impedance controlled trace. Maintain consistent trace widths to ensure controlled impedance. 05; The manufacturer provides a stack up as well as a 2D calculator for determining trace width: here The manufacture's calculator computes 3. Using this calculator, based on my earlier question I'll need to make sure to approach 90Ohms with the "Impedance (differential)". h : Trace thickness, t (input3) : Impedance, Zo (input4) : OUTPUT Microstrip Width, mils : EXAMPLE: Inputs: Relative dielectric permittivity = 3. 0. to select appropriate isolation materials, layer thickness, trace width, distance between traces,. Using an impedance control PCB calculator, the engineer determines that 50-ohm single-ended traces require a width of 6 mils and a spacing of 10 mils. Fabricators give trace impedance tables as guides to designers that need to implement controlled impedance in their PCBs. Single Ended Impedance Ω. What is the width of a trace for 100 ohm impedance? The width of a trace for a specific impedance depends on the dielectric constant, height above the reference plane, and other parameters. In a controlled impedance design the designer specifies the impedance rather than the trace width. 378 [mils/oz]) For IPC-2221 internal layers: k = 0. For this example, we will use 2. Dielectric constant = 3. Stripline Trace. Select a Configuration. 66, the trace height is 1. The aim of the Impedance Calculator is to support the. Equations Altium Designer includes a PCB trace impedance calculator, PCB trace width calculator under IPC 2152, and a plethora of other important design tools. How to calculate PCB Impedance? First, determine the dielectric constant. Sierra Circuits Impedance Calculator. Stripline Impedance. PCB Trace Width Calculator. trace width for a characteristic impedance of 50 Ohms on Dk = 4. The CircuitCalculator. This form of microstrip is composed of two traces. Twisted-Pair Impedance Calculator; Stripline Trace Width Calculator; Embedded Microstrip Impedance Calculator; Microstrip Wavelength Calculator; Stripline Crosstalk Calculator;. A temperature rise in PCB trace width calculator is a tool or software that helps engineers and designers estimate the temperature rise in a PCB trace based on the trace width, current, and other parameters. Optimize power transfer with our Impedance Matching Calculator. Microstrip lines have three parameters that we can change to achieve 50 ohm impedance: copper thickness (T) substrate thickness (T) track width (W) Due to design constraints, there is only one parameter (track width,) left to achieve 50 ohm. Most CAD systems provide an impedance calculator for this. This Mantaro calculator tells me that I need a trace width of 11. . The fabricator will advise what material thicknesses are available and what precision they can achieve for trace widths. Calculate the pcb trace impedance of. Select a Configuration. Figure 2. The new version includes: Additional dielectric materials. TransLine. The characteristic impedance is given by: Eq. View All Tools. Embedded Microstrip Impedance Calculator. Best is 5mils, but 4mils is OK, too. R. Call us: +1 (800) 763-7503. A calculator designed to calculate the trace width of a stripline based on the maximum current rating Embedded Microstrip Impedance Calculator This calculator helps you compute the characteristic impedance of an embedded. In a controlled impedance design the designer specifies the impedance rather than the trace width. Since impedance traces are not specified here, the manufacturing focus is completely upon building a board within +/-10% tolerance of the specified dielectric thickness from layer to layer. 25 Ohms and is therefore out of the limit. Coil Inductance Calculator. Impedance calculationFinally, the impedance calculations will give you the correct trace width to work with to hold the impedance value that you need for your sensitive high-speed trace routing. H (Dielectric thickness) : The Smith Chart graphically maps S11=reflection coefficient= (ZL-Z0)/ (ZL+Z0) to Load Impedance (ZL), normalized to Z0 (source impedance = center of chart). H1=> 8. 035mm and Er = 4. ( 0. It's open-source to download. Flex thickness x 6. The dimensions of traces and their spacing significantly affect impedance values. At the point of bending, the trace width is 1. For this reason, trace width is important in the design of striplines. PCB Trace Width Calculator & PCB Trace Resistance Calculator per IPC-2152. (Trace width) : mm mils:To help you achieve this feat, Sierra Circuits has introduced the Bandwidth, Rise Time and Critical Length Calculator. The impedance of a trace is decided by its width and height from a reference plane. The microstrip is a very simple yet useful way to create a transmission line with a PCB. RF Attenuators. T. For example: Yellow Violet Red Gold: 4 7 x100 ±5% = 4700 Ohm, 5% tolerance. Just enter the given values for trace thickness, substrate heights, trace width and substrate dielectric in the calculator above and press the "calculate" button. By inputting the dielectric constant, trace width, trace height, and trace thickness, the calculator provides a quick and reliable way to determine the required trace geometry. This is good enough so we can now switch to the “Coupled Microstrip Line” calculator. 03) it gives me almost 160 Ohm - and even if use 53mil conductor height or. Understanding coax can be helpful when working with it. T is the trace thickness [oz/ft 2], W is the trace width [mils], R is the resistance [Ω], ρ is the resistivity parameter, whose value for copper is 1. You can use the following PCB impedance trace formula to calculate its circuit impedance: εr : The dielectric constant of the material;. Tuning the Width and Gap Settings. Useful calculators and converters for PCB layout engineers and designers. These calculators give us essential trace spacing and differential pair spacing if needed. 0; 1 <. To calculate the proper trace width for routing, PCB layout designers must add these parameters to the circuit's impedance specifications. Provide values for the four parameters H 1, H, T, W, and the relative permittivity of the dielectric. 63mils via height. The ground plane separation is 6 mils for layers 1 and 2 and 8 mils for. Trace Spacing Calci 3. W: trace width: T: trace thickness: H (/H1)Once these decisions are made, a designer needs to determine the PCB trace width required to hit their required PCB transmission line impedance. The Calculator. 0; 1 < ε r < 15 ) Select the units for all dimensions: mm mils. 49. 7E-6 to 2. Embedded Microstrip Trace. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. You can calculate maximum current by using the formula A = (T x W x 1. Input Your Specs to Get Started. You’ll need to know the dielectric constant of your substrate at the relevant frequency and some parameters in your. 024, b = 0. 4 mm, trace spacing S = 0. The new IPC-2152 standard is a significant improvement over the previous IPC-2221 standard. The efficiency of transmission of the embedded microstrip greatly depends on its characteristic impedance. There are a few points to note about this. The aim of the Impedance Calculator is to support the designer in such a pre-layout design phase. The information should include the impedance value, the trace width, the spacing for. To use it, specify the trace dimensions and the ambient temperature. 25 mils , t = 1. Changing the stack-up will affect the calculated trace width for impedance-controlled traces; however it will not automatically update existing traces. In the case where there is a plane present, a correction factor is applied to determine the required copper. g. The impedance Z 0 of a transmission line consisting of a circular signal conductor having a diameter d and centered between parallel ground planes separated by a distance h is given by: Eq. You can use our trace width calculator to design the right traces for your boards. You can use our trace width calculator to design the right traces for your boards. What is the width of a trace for 100 ohm impedance? The width of a PCB trace for a specific impedance depends on factors like dielectric material and thickness. 949. PCB Trace Width Calculator. What are the limits of the trace width calculator? The formulas used in the calculator are based off IPC-2221 (formerly IPC-D-275), which covers up to 35 Amps, trace widths up. copper trace on a 4-layer board with 8 mil thick dielectric and Dk = 4. 254mm, spacing between both is required 0. . 99:. Dual Stripline Impedance Calculator: Provide values for four of the five parameters H, C, T, W, Zo and the relative permittivity of the dielectric. 98mil. 7563 mm (~30 mils). Note that vias are made out of plated copper which typically has a resistivity of 1. PCB Trace Width Calculator. These important design features are incorporated into your design rules, making impedance-controlled routing quick and easy. 2. Tightly coupled pairs (within a pair) are quite common and this has the advantage of having a somewhat higher single ended impedance on a per track basis within a differential pair which is often easier to implement. This type of PCB impedance calculator provides the most accurate results for any geometry. Convert psi to bar, kgf/cm2 to psi, bar to kgf/cm2, and other units like pa, mmH2O, inches H2O, psf and atmosphere with the pressure measurement conversion calculator. 906mil. Just as important as determining an appropriate trace width for a single-ended trace is determination of an appropriate spacing between two traces in a differential pair. Reference: R. input values trace thickness: 1 oz/ft^2; substrate height: 1. Figure 24. Sierra Circuits’ Trace Width, Current Capacity and Temperature Rise Calculator is an advanced PCB tool that works based on the latest IPC-2152 standard. 19mm) traces with 7. 7mil. 7 pages of equations to evaluate the impedance. 6mils that is the same as given in the stack-up. For example, if you wish to input "25000000", just type "25M" instead. 4mil; Dielectric Thickness: 3. 1 of the Microstrip Calculator using H2 in place of h, εr,eff can be computed as specified in Eq. To use this tool, enter the values for trace thickness, substrate height, trace width, trace spacing and subtrate dielectric in the calculator above and press the "calculate" button. There are many other free calculators available. The shortcomings of crosshatch or mesh as a high frequency return path. EEWeb provides a suite of Microstrip Impedance Calculators as follows: Microstrip Impedance Calculator; Embedded. Thermal. Tool calculations are based on the IPC-2152. 7 x 10-6 ohm-cm αcopper (temperature coefficient). 031. What is Microstrip Impedance? For my results, I find that the minimum inductance is 292 nH per meter when ( w/h) = 1. You can build your own board layer stack or you can choose to work with one. There are four different types of impedance used in characterizing differential trace impedances. Fabricators give trace impedance tables as guides to designers that need to implement controlled impedance in their PCBs. ViaMin. 6 mm is used) can anybody help me how to calculate 100 ohm impedance. 75 mm=30 mil). INPUT DATA. This is the structure that the freeware impedance calculator analyzed and incorrectly reported the impedance to be 50 ohms. Use an impedance calculator to determine the trace width (W) and spacing (S) required for the specific board stack-up being used. The Fairchild application note also says that the differential characteristic impedance of the D+ and D- lines should be 90 ohms. 6 ohms. o use this calculator, enter the parameters of the regulator . It calculates the trace width as 13. The calculator is set up to handle an asymmetric arrangement, where traces are not centrally located in the PCB layer stack. Determining trace impedance and propagation delay in PCB traces takes a trace length calculator and impedance profiler tool, and these features work best when they are integrated into your PCB design software. Most designers take the controlled impedance approach and devise a target for their trace width/spacing for single-ended and differential channels. For a 0. ε: Dielectric constant of the PCB material. Altium Designer includes a PCB trace impedance calculator, PCB trace width calculator under IPC 2152, and a plethora of other important design tools. PCB Trace Width Calculator. This time I am trying something new. See below for the definition of these impedances. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a calculated impedance according to the IPC-2141 standard. To calculate one of these quantities, the other two must be known. 92. T. W: Width of the microstrip trace. There are four different types of impedance used in characterizing differential trace impedances. Ω. 3. This online microstrip impedance calculator calculates the characteristic impedance of the microstrip (Ω), W/H ratio, and effective dielectric constant (εe) by entering the value of dielectric material relative permittivity (εr), the width of the copper trace (W), and dielectric height (H). Enter the values of trace width (w), trace thickness (t), trace dielectric thickness (h), overall dielectric thickness (h1), and the dielectric constant (er). It’s a three-in-one. T T = trace. From the target impedance and target tolerance, the software calculates the Trace Width. You will see the trace width is 5. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. This tool will also compute the resistance of the stripline, the voltage drop on it, and the resulting power dissipation. Features: Three-in-one calculator. The Calculator has the following tools:. The IPC-2221 standard and IPC-2152 standard both include this guidance on designing for thermal reliability, and there has been some debate as to the applicability of each standard. As you adjust the width of the line, you can eventually get the microstrip impedance calculator to converge on the desired impedance value, and you have finished designing the microstrip trace. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. To reach 90Ohms, there are 2 ways (or there is another, please advise!): 1. So, the dielectric at my 5-6GHz frequency range is 3. 0683mm. Impedance and PCB Stacking The trace impedance is affected by many factors such as the width of the trace, th e thickness of the copper,Here are the steps to validate your design using Better DFM: 1. 062. Trace impedance is detrimental to high-frequency signals, especially when the. This procedure produces the result ( w/h) = 1. PCB Trace Impedance Calculator. Note: ρcopper = 1. Also for differential LVDS signals the tool can calculate the trace width and spacing for 100 ohm impedance for a given stack up setting. Sierra Circuits’ Via Thermal Resistance Calculator is an advanced PCB design tool that expedites the process of designing thermal vias. 3mm. Patch Antenna Calculator. 4. Using this application, you can quickly identify the thermal resistance of a single or a combination of vias. 5 oz. ) Dramatically decrease the spacing in between differential pairs: I know:In any case, you do not want to use the Altium estimate for the trace width to achieve a given impedance to design an antenna. Off the top of my head, I can think of Polar and z-calc but I never liked these. After changing W to 14 mil click “Analyze” and you can see Zo is now calculated to be 49 ohms. Used by PCB manufacturers to refer to selection of dielectrics and thicknesses to hit a trace width/spacing specification, or modification of trace geometry, to hit an impedance target. 3 is a plot of impedance versus trace width for the three most common types of transmission lines in PCBs-- surface microstrip (SMS), buried microstrip (BMS) and centered stripline (CSL). Correct track impedance is the first point usually made in various online sources I've found on the subject, so I tried to get the microstrip impedance calculator to get as close the desired 100 Ohm. A standard trace width for an ordinary signal (no special requirements) may be in the 7-12 mil range and be as long as a few inches, but there are many things that should be considered when defining the width and length of a trace. That structure is called a coplanar waveguide. Microstrip Trace Impedance Calculator PCB Trace Width Calculator. 6mm thick PCB with 4 different traces on it, 8, 10, 12 and 14 mil wide. Use our online tool to calculate the minimum trace width for a given current and copper weight. ] Internal Layer Results: Copper Area: External Layer Results: [Mils] [Square Mils] [Volts] Trace Width Calculator Results: Via Current. Differential Impedance Ω. Having carefully specified the board/prepreg material, I also ask for tolerances and based on that calculate the widths for eg. These important design features are. they normally use 7. On a typical high speed multilayer board you may have something around. 50 Ohms and then specifically sets this trace width as a qualifier. W: Width of the microstrip trace. The minimum trace widths and spacing are manufacturer and process dependent and usually vary between 3mils. See below for the definition of these impedances. Er1=>4. Currently, thermal calculators for computing the trace width are based on IPC-2152 and IPC-2221. Use the following guidelines. 393 mm, the required trace width for this particular inductance value is w = 0. To use this tool, enter the values for trace thickness, substrate height, trace width. 3. A PCB. First, the Area is calculated: Area [mils²] = ( Current [Amps] / (k* ( Temp_Rise [°C] )^b) )^ (1/c) Then, the Width is calculated: Width [mils] = Area [mils²] / ( Thickness [oz] * 1. Track width (w) = 137 micron. The Track Width tool calculates the trace width for printed circuit board conductors for a given current and temperature rise. e. So, you need to calculate how much resistance a PCB trace can provide. One of the most common inquiries that we encounter at Bittele electronics are regarding our standard trace widths for a given board thicknesses and copper weight. If a signal encounters impedance discontinuity, it will generate jitters in PCBs and hampers the signal integrity. passive-filter-calc-js. 8W + T)] Where: Z: Characteristic impedance of the microstrip trace. Microstrip Impedance Calculator. dh-calculators-head-americas. A A is the cross section area, in mils 2; and. Click on Setup -> Constraints > Electrical Constraints Set - > Differential Pair Value - > Calculator > If you put 10 in the Line Width, the calculator calculates the single ended as well as differential impedance. Calculators Capacitor charge Impedance Matching Calculator Inductance Conversion Op amp voltage & gain Passive Filter Calculator PCB trace width Pull up Pull down resistors Transformer Turns Calculator Twisted pair impedance. 41)] * ln[5. Our current online trace width calculator is useful for clients who need to calculate the minimum/maximum trace widths for. Calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board trace geometries. Note: The trace on the inner layer need to be much wider than the trace on the outer. d – wire diameter. 3mil seems like a substantial enough difference. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. This is more than the to times trace width which is recommended (also read as close as possibly). 393 mm, the required trace width for this particular inductance value is w = 0. A stripline is similar to the microstrip except that the flat conductor is now. The trace width and spacing for a certain impedance may be obtained using impedance calculator s. The manufacturer will test the impedance on a test coupon. Back to Resources Use our free impedance calculator to ensure your design is error-free! Impedance Calculator Structure Type Single Ended. ALGEBRAIC EQUATIONS Single Track For the stripline of Figure 2 with a symmetrically centred track of zero thickness, Cohn[3] has shown that the exact value of the characteristic impedance is 4. The following formula is used to calculate the differential impedance of a microstrip: To calculate the differential impedance of a microstrip, divide the characteristic impedance of the microstrip by 2. The Simbeor impedance calculator calculates the width(s) required to achieve the specified impedance. a) JLC7628 Stackup:This page covers Microstrip Width Calculator. Here is a couple of calculator links:These calculators use a solution for the trace width in terms of impedance, or they use an iterative numerical technique to calculate the trace width from impedance. IPC-A-600 Inspectors. Going Forward with a Trace Impedance Calculator. 414 times higher than the actual trace width. 5mil clearance on a 63 mil board (1. Differential Impedance of. 6 mm; trace width: 1 mm; trace spacing: 0. The surface finish is neglected. 81. Going Forward with a Trace Impedance Calculator. Distance between tracks (s) = 254 micron. Board thickness (h) = 50 micron. Before the length-tuning section, the odd-mode impedance of the traces in each pair is 50 Ohms, so the differential impedance of each pair is 100 Ohms. Figure 24. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. The calculated impedance was 36. It is not uncommon that the calculated trace width will be a value that cannot be ordered, for. Thank you. You only need to know the resistance, the inductance, and the capacitance values connected in series or parallel. Trace width/SpacingMin. The trace width, spacing, and impedances along each trace are shown along the length of the two routes. 6mm 2. Next, determine the trace. H 2 H 2 = subtrate height 2. Board thickness (h) = 50 micron. This calculator is designed to compute the maximum allowable current that can flow through a stripline. Using the EEWeb Microscrip Impedance Calculator, I find that with 1oz/ft^2 copper and a substrate height of 0. 2-side PCB, one side with signals, the other with GND. This tool uses formulas from IPC-2221 to calculate the width of a copper printed circuit board conductor or "trace" required to carry a given current while keeping the resulting increase in trace temperature below a specified limit. When I attempted to validate this against other online calculators I find that some agree and some differ. The surface finish is neglected. The trace width required to deliver a specific impedance can be calculated as part of an impedance profile, in the Impedance tab of the Layer Stack. Impedance quality = Q = L/Rs 2. 4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6. 4 , h = 4. Calculate the width of a copper-printed circuit board conductor (internal trace) necessary to carry a specified current. The best high-speed performances are usually accomplished if the width of the component is close to the track. Cite. For more accurate numbers, you can use a trace impedance calculator online. 35 ohms. Trace top width: Trace base width – 1 mil: Nan Ya Plastics NP-155F (4 to 8 layers) Core Thickness: εr: Prepreg Type: Resin Content: Nominal Thickness: εr: 0. The characteristic impedance of the trace can be calculated using the below formula: Formula to calculate characteristic impedance of a PCB trace.