58: 100:. First, calculate the area according to the following formula: A = (T · W · 1. calculate the impedance and capacitance of PCB traces. Copper Temp_Co = 3. 37) If H1<1. For a typical 1 oz copper PCB, approximate widths are: 10 mils (0. Frequency Keeping high speed. Traces such as these are found on adjacent planes with the return being identical to the trace both in length and in. 21 STRAY INDUCTANCE 12. Inductance is the ability to store energy in a magnetic field, and coils are a common way to create inductance. Ale kalkulačky trasovací indukčnosti PCB v těchto případech porušují pravidla. Wire Microstrip Impedance Calculator. 44, c = 0. The microstrip is a very simple yet useful way to create a transmission line with a PCB. Just enter the given values for trace thickness. Trace Inductance calculator for wide traces over a ground plane with trace width (W) much larger than substrate thickness (T). 54. Impedance in your traces becomes a critical parameter to consider during stackup design for high-speed PCBs, but the. This tool will also compute the resistance of the microstrip, the voltage drop, and the power. For this calculation the diameter and length units are in cm. 2: traces 12. Build a model from experimental data of impedance vs. In other words, this is the impedance the signal actually experiences as it travels on an individual line. Sierra Circuits’ Via Impedance Calculator uses the physical dimensions of a via to calculate its capacitance, inductance, and impedance. 023mV/A. You can see the input HV connector that goes through the DC blocking HV cap and the HV reed relay. Choose a calculator to tune your PCB design. A picosecond is 1 x 10^-12 seconds. However, if you bring some copper near a trace, their will be some additional mutual capacitance and inductance that will modify the impedance of the trace. Lcoil = μrμ0N 2A l = μrμ0N 2πr2 l L c o i l = μ r μ 0 N 2 A l = μ r μ 0 N 2 π r 2 l. The calculator uses the current sheet approximation formula. The trace resistance of a microstrip is important in determining how much power it dissipates. Microstrip inductance calculator. Using Equation 6, we calculate loop inductance as L=65. Eddy-current sensors are widely used for precise displacement sensing and non-destructive testing. The term “transmission line” refers to the behavior of a trace on a PCB rather than its construction. HELP. PCB Trace Resistance Calculator. 15mm). Air Core Flat Spiral Inductance. What is the rule of thumb for trace inductance? A common rule of thumb for trace inductance is that wider and shorter traces have lower inductance. Where: H is the height of the PCB above the ground plane. 56 MHz the impact of stray capacitance cannot be neglected and. Mounting inductance can be minimized by choosing smaller capacitor packages. It should also be noted that blind and buried vias involve a higher production cost, so it is advisable to plan their use in advance in order to respect the budget allocated to the PCB. Always, ensure symmetry of the build-up. µr (mu-r) is the relative permeability of the PCB material. The current-carrying capacity of a piece of copper is determined, to a first-order approximation, by two factors — the rate of heat generation and the rate of heat dissipation. inductance of the signal–ground loop, as the effective inductance associated with a large ground plane can be neglected (see the expression of the effective inductance L e gnd in Table A. Stack Exchange network consists of 183 Q&A. formulas to calculate the self inductance L. 378 [mils/oz/ft2]) (I) Then, calculate the maximum current: IMAX = (k · TRISEb) · Ac (II) Where: A is the cross-section area [mils 2 ] T is the trace thickness [oz/ft 2 ] W is the trace width [mils] I MAX is the maximum current [A] T RISE. If the bottom of the board (Or any other layer) was a groung plane, it may be ok, but on a single layer PCB, it would be an antenna for parasitic signals. One commonly used formula for calculating the characteristic impedance of a PCB trace or transmission line is the capacitance per unit length formula: Z0 = 1 / (C / L) where Z0 is the. This phase shift found between the current and voltage in the inductive circuit, nevertheless, prevents them from being exact. You can access these calculators in the CAD software or online. Output voltage = 0. N = Number of turns. As the coil is suddenly demagnetized, the. Select a configuration: Microstrip Trace. W. External Copper Thickness: Copper weight for the top and bottom layers. This formula is from the following reference. One commonly used formula for calculating the characteristic impedance of a PCB trace or transmission line is the capacitance per unit length formula: Z0 = 1 / (C / L) where Z0 is the. For an embedded (internal) microstrip, the formulas provided in paragraph 4. Coplanar traces are common in printed circuit boards. l = Coil length in inches. 10. 1 of the Microstrip Calculator using H2 in place of h, εr,eff can be computed as specified in Eq. Log In No account yet? You can Sign Up for free!. 002 * (w/d) * (ln(2w/d) + 0. Assumptions and Limitations. Modeling approximation can be used to understand the impedance of. Trace width is an important design parameter in PCB design. This calculator computes the trace width of a microstrip given the following information: maximum current, trace thickness, temperature rise, ambient temperature, and length. Trace over a ground plane: microstrip line. This impedance is dominated by the physical separation between your power rails, traces, and internal planes in your board. However, these prospects depend on the uniformness of the. Impedance matching is the way of configuring the input impedance of a load or the output impedance of its signal source. Multi-Layer Coil Inductance Calculator. This calculator will convert voltage or power gains into decibels. First, calculate the area according to the following formula: A = (T · W · 1. This online electrical calculator helps you determine the microstrip crosstalk on PCB based on the trace spacing and substrate height. 24 pH, where pH is units of microhenries. If the Length, l, to diameter, d, ratio is known, you can calculate the Inductance, L, series resistance, Rs and the aspect ratio l/d is related to Q = L/Rs for a given conductor material. 0pF per inchBlackCoffee August 12, 2022, 4:44pm 2. The power plane pair between the capacitor and the IC adds to the effective inductance. Coplanar Waveguide Calculator. A PCB impedance calculator uses field solvers to accurately approximate impedance values. As rise times increase, the resulting impedance becomes more noticeable. This online tool helps calculate the maximum current through the PCB trace, voltage drop, inductance,. The surface finish is neglected. Discover a multitude of applications with EMWorks specialized electromagnetic simulation software, transforming solutions for engineering and design challenges. The Track Width tool calculates the trace width for printed circuit board conductors for a given current and temperature rise. A very quick and helpful tool. By the same token, each trace has capacitance distributed along the trace and the return path signal, which is a. 1427·10 -9 H = 1. All the units are in SI (Iternational System): [m] = meter. Figure 3 shows an example current loop that the signal trace and its return path created. Learn how to use a PCB Trace Calculator that can help you design compact and efficient printed circuit boards. The result will be displayed. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. L is inductance in uH. If you care about the inductance of the inductor (rather than the inductance of the circuit) then do your best to keep those to a minimum, at least by using the shortest possible wires. The PCB Designers specify the copper plating weight in oz. section 12. What is typical PCB trace inductance? Typical PCB trace inductance can vary depending on the trace geometry, but as a rough estimate, it might range from a few nanohenries (nH) to a few microhenries (µH) for typical PCB traces. In this case, there will be both an IR component due the small trace resistance (RM) and an L*dI/dT term due to the trace inductance (LM). 26. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. Here, = resistivity at copper. We specialize in both Small quantity, Quckturn, and Production printed circuit board Quantities. For a 1 inch trace, this value would have a total inductance of ~7. Traces on PCBs are small and therefore have small inductance levels. Jensen, “Accurate Models for Microstrip Computer-Aided Design,” 1980 IEEE MTT-S Digest, pp. 36) Co Equation: IPC-D-317A (Eq. A copper Thickness of 1 oz/ft^2 = 0. An open-source tool that allows for a fast and precise analytical calculation of multi-layer planar coils self-inductance, without any geometry limitation is proposed here. Brad - January 29, 2008 Ivan, Inductance requires a few more input parameters, so I have a separate calculator:PARAMETERS of inductor traces: witdh = 0. (2) Where: H = thickness of dielectric T = thickness of microstrip conductor W = width of microstrip conductor Valid for 0. I believe that some friends have been able to guess what factors affect the circuit impedance from the above PCB trace impedance calculation formula. This phase shift found between the current and voltage in the inductive circuit, nevertheless, prevents them from being exact. 2. 1. O. With the RF Attenuator utility you can calculate the values of the resistors needed for different types ofThe Coil32 program is coil inductance calculator, that computes inductors and chokes on different cores and also calculate LC circuit parameters. Additionally, using a ground plane underneath the trace can help reduce inductance. Use stripline routing for better far end crosstalk performance and a tight impedance tolerance, and keep trace lengths shorter than the maximum allowed length limited by the full-channel IL and eye diagram simulation results. l= 4. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. 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. calculate the pcb impedabce and capacitance of stripline. 8mm (0. First choice: Don't. Spread the love Trace Capacitance Calculator Trace Capacitance Calculator Trace Length (in meters): Trace Width (in meters): Dielectric Constant: Calculate Capacitance FAQs What is the capacitance per inch of a trace?. What's the edge rate or rise time of your pwm signal going to. Equation. Internal traces : I = 0. 2. 725 For IPC-2221 external layers: k = 0. At some point the amplitude will stay constant. Coils produce a magnetic field when current flows through them, storing energy in their magnetic field. Plug in the values into the inductance formula: L = N²/R. 949. The target impedance value of a design is given by the equation: Z = ( V x ripple%) / ( 50% x Imax) The formula represents a combination of voltage fluctuation and transient current. By determining its trace resistance, the contribution of a microstrip to the overall circuit resistance can be evaluated. 2dB (at the power level) Configuration of the circuitry ranges from 50Hz to 1kHz . Traces such as these are found on adjacent planes with the return being identical to the trace both in length and in. 0 9 / 15 2011-04-28 0. 5. Using the Neumann integral formula, the expression of inductance is obtained. Enter the values and hit Width Button to calculate the required trace. How much inductance is in PCB trace? The inductance of a PCB trace depends on its. 19 inductance 12. 031”) trace on 0. I am also told my trace is to be 1000 micrometers long (1mm) and 45nm wide. Calculations provided on this page are a simplified subset from EMI Analyst models. A number of months ago I used your calculator in reverse to determine the current carrying capability of traces on my PCB. See more . Using the example numbers: L = 20 x 10^-3 * 12 x 10^-12 = 240 x 10^-15 henries or 0. 3. Current and heat considerations: Depending on which. 5 voltage drop in signal leads—"kelvin feedback" 12. Also see the via calculator. The formula for mm to mils is simply the reverse . It is interesting to note the following. The PCB Impedance Calculator in Altium Designer. The multi-turn inductors are used for higher inductance value design. Conductor is assumed to have zero thickness and to have uniform height. 3 can then be used to design a PCB trace to match the impedance required by the circuit. Trace inductance - traces that bring power to components also contribute some inductance to the PDN. 031”) thick PCB (FR-4) has: ˜ 4nH and 0. Traces carrying high speed signals should be as short and straight as possible. Advanced Circuits is MIL-PRF-31032, MIL-PRF-55110G, AS9100C, ISO 9001:2008 Certified, IPC 6012 Class 2, 3 and 3A Qualified, and ITAR Registered. This tool is designed to calculate the inductance introduced by an edge-coupled trace. This tool is designed to calculate the inductance of a square loop of wire given its dimensions (width, height and diameter of the wire used). NOTE: numbers are in scientific notation (e. Bringing the GND plane closer to the high dV/dt. PCB Coil Calculator. Here’s how you can size your traces correctly and ensure they have sufficiently low PCB trace inductance. The transmission line geometries are cross sections and the. The mutual inductance equation is: The terms in the denominator state that the odd-mode and even-mode capacitances must be evaluated at epsilon = 1. In this case, there will be both an IR component due the small trace resistance (RM) and an L*dI/dT term due to the trace inductance (LM). A trace is a conductive path on a PCB that carries electrical signals between components. FIGURE 2: PCB COPPER LOOP 34mmx12mmx1mm Using Equation 4, we calculate radiation resistance at 434 MHz as Rrad = 0. L is inductance in uH. 435A. Very typical/basic knowledge…. Generally, when we talk about the. In other words, for proper impedance control, the load impedance must be equal to the characteristic impedance of. Place the ground plane 1 dielectric away from signal and power planes. Assumptions and Limitations. PCB Impedance and Capacitance of Asymmetric Stripline. This calculator computes the inductance of a microstrip etched on a PCB. Knowing that the test cable and the test output are 50 ohms, it is possible to use Equation 3 to calculate the impedance of the trace under test. 8pF per cm ˜ 10nH and 2. The characteristic impedance is given by: Eq. Optimize power transfer with our Impedance Matching Calculator. effect on the equivalent inductance. Conditions: W>>H, H>T. STRIPLINE CALCULATORS, APPLETS, ANIMATIONS &. The inductance of the coplanar trace calculation requires 4 variables: W - Trace Width; S - Trace Seperation; L - Trace Length Inductance: L =. 2. Since the goal of trace design in a PCB is generally to get close to an impedance target, designers will need to use some equation to calculate the impedance of a trace or a transmission line impedance calculator to properly size a trace in a PCB layout. L = Inductance in microhenrys (μH) Coil dimensions for calculating inductance. The inductance of a path depends on the area of the loop created by the current flow. The vias were placed in order to further reduce impedance but since we are talking AC here, the signal path will be. 561235. 6e-3 m and 1″ = . PCB coils refer to coils that are directly fabricated onto printed circuit boards using conductor traces on the board layers. One should always check carefully whether a calculator implements these equations under the appropriate approximations. In English units, ( h, s, and r in inches, L in nH) the constant μ/2π equals 5. Specific designs may require adjustments based on factors like temperature rise and copper weight. The inductance calculated in this tool is the loop inductance created with the wire and its return path on the ground plane. For a given form, an inductance is characterized, as shown in Fig. Now consider a sine wave coming into the trace. •Based on the PCB manufacturing rules, set: –a. PCB Assembly only $30 High quality PCB. A number of months ago I used your calculator in reverse to determine the current carrying capability of traces on my PCB. 0227 Ω. The equation is as follows-. 031”) trace on 0. In order to acquire inductance parameters of the coils on PCB, a method is proposed to calculate the self-inductance and mutual inductance based on the Neumann formula. 8. Although JLCPCB can produce boards with 2 oz external copper, the calculator only supports 1 oz because (1) the wider. A series of simulation studies are conducted in ANSYS to analyse the relationship between the overlapping area, winding loss, magnetizing inductance, core loss, and parasitic capacitance. Advanced Circuits is MIL-PRF-31032, MIL-PRF-55110G, AS9100C, ISO 9001:2008 Certified, IPC 6012 Class 2, 3 and 3A Qualified, and ITAR Registered. Exaple reflection and crosstalk data in a routed net. µr (mu-r) is the relative permeability of the PCB material. The resistance of a trace on a PCB depends on several factors, including the width and thickness of the trace, the length of the trace. 7*10 7). 33. $egingroup$ Also, beware of added inductance from the wiring in the rest of your circuit. And as the PCB circuit complexity. Coplanar traces where one trace is the signal and the other trace is the return path apply to this inductance calculator. You can then check this PCB trace width against. So a PCB trace . 2mm trace width, 45 turns, inductance= 20uH and 0. 508mm via will addA track starts behaving reactively at the point where the wavelength of your signal approaches the order of magnitude of the size of the track. With t = 0. How to Do PCB Modeling For a Power Converter Figure 2. It is important to note that in industry we can find that some differential pairs are routed this way for a strong coupling, but the actual return for the signal is on a. Enter one of the three values and the calculator will output the other two. The method to calculate inductance was proved by the simulation using finite element analysis and measurement using an LCR meter (20 Hz–1 MHz). ant. An edge coupled trace inductance calculator is a tool used to calculate the inductance of an edge coupled trace on a printed circuit board (PCB). com +86-159-8660-8719; Send Your Inquiry Today. Don’t Use a Via Inductance Rule of Thumb. Conductor is assumed to have zero thickness and to be uniformly spaced between the ground planes. Note: µ0 = 4¶·10 -7 [Hm -1 ] (Absolute Permeability)The wavelength of the signal that can propagate effectively inside a microstrip is called the guided wavelength. This shows that widening a trace will reduce the inductance of. In these PCBs, the PDN should be arranged with at least one power/ground plane pair placed closely to. A coil inductance formula is based on the basic loop inductance. E. Here’s a simple guide to PCB trace inductance and sizing trace widths for your board. *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. Inductance is a property of an electrical circuit that describes the amount of energy stored in the magnetic field created by the current flowing through the circuit. If the trace will not be used to route high-speed or RF signals, then we worry less. w is the Width in cm. For high-frequency signals such as GHz bands, PCB traces don’t act like simple connections. Usually, the lower minimum widths tend to be much more expensive compared to higher minimum widths. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. The yellow traces that you see, exist on 5 of the 6 layers. The following will list all the factors that affect the. Loop Inductance Model. Comparison of smooth (RMS=0. 3 ohms. PCB Coplanar Waveguide Calculator RF PCBs can be complex boards that need careful interconnect design and layout. The Calculator has the following tools: Regulators. PCB Trace Impedance Calculator. of typical printed circuit board trace geometries. e. Inductance is the ability to store energy in a magnetic field, and coils are a common way to create inductance. 5+0. If you are using very fast rise/fall times (regardless of frequency) and ringing is your problem, you'll need to use a trace impedance calculator, with the trace impedance matched to the. Loop Inductance Model. 5+0. Select the box with the geometry that you would like to calculate. This calculator calculates the characteristic impedance, capacitance per unit length, effective propagation delay, inductance per unit length using relative permittivity, height of dielectric, width of trace, trace thickness values. Trace inductance that includes the current path through the ground net; Trace capacitance with respect to the ground net; Together, these values define the transmission line impedance,. Commonly fabricated with printed circuit board (PCB) technology, a microstrip antenna calculator tool is an electrical transmission line that is able to transmit RF signals. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. Resistance calculation. Inductance (in a General sense) is a function of Wire/Trace length, cross-section-area…material properties, etc. Figure 1 Cross section of a PCB 1 E. 8mm (0. The conductor and ground plane are separated by a dielectric. Adequate trace width is necessary to ensure the desired amount of current can be transported without overheating and damaging your board. Therefore it doesn't change (to a first order approximation) at different frequencies. This calculator is designed to calculate the characteristic impedance of a symmetric stripline - a flat conductor between two ground planes whose distance between the conductor and the planes is the same for both reference planes. There are many factors that go into calculating the width of an impedance controlled trace. ABOUT US. 5. F-A t t enua t o rs. See more . THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. The inductance of a PCB trace determines the strength of any crosstalk it will receive. 6uH and 0. The resistance of a trace on a PCB depends on several factors, including the width and thickness of the trace, the length of the trace. Figure 2: Types of via holes (Source: Altium). com If it. 3 shall be used. The real structure of any. Coils produce a magnetic field when current flows through them, storing energy in their magnetic field. 3 0. NOTE: For the wire radius, enter the trace width of the PCB traces. The calculator below uses Wadell’s. One challenge in designing PCB interconnects is maintaining system impedance while reducing crosstalk, which requires reducing trace inductance. Input the diameter, length, and number of turns of the coil to obtain the desired result. You’ll need to get the Trace Widths and Thickness and Length. 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. The Via Inducatance according to Howard Johnson can be given by the following formula ( which is not very accurate as it does not take into account the return path of the current). d = Winding depth in inches. Embedded Microstrip. If. The standard signal integrity tool in a PCB editor for crosstalk and reflection waveforms can help with a lot of up-front qualification of signal behavior (rise/fall time, overshoot, crosstalk, consistent impedance, and ringing) before moving into a more advanced analysis tool. 15 ohms resistance. Skin Effect Calculator June 18, 2007. 48ohms resistance. 15 inches and a length of 1/4 inch. 2235* (w+h)/b) where: w is width of the strip in inches, b is the length in inches, h is the distance between the strip and the ground plane, and. 26) Led Resistor Calculator. 4. 1. Strip length: 180 inches. The calculator then uses a formula to calculate the width and spacing of the trace or transmission line required to achieve the desired characteristic impedance. R 50Ω R 50Ω RM VS LM VS VI V=L V=IR d dT Scope Input I Figure 7. Inductance Conversion. Many magnetic field coupling circuits, such as chokes and transformers, take advantage of a coil’s magnetic storage properties. On my boards I use 0603 packages because I often assemble them by hand; if the board will be assembled by machines,. Edge Coupled Trace Inductance Calculator. The inductance calculated using this tool is the external inductance of the loop bounded by the flat conductor and the ground plane. There are four different types of impedance used in characterizing differential trace impedances. Using the example numbers: L = 20 x 10^-3 * 12 x 10^-12 = 240 x 10^-15 henries or 0. However, at 13. . Capacitance Time Constant Calculator_Online Calculation Tool Standard Resistance Resistance Quick Reference Table_Online ToolsThe wider a trace is, the easier it is to fabricate. The inductance of a wire loop is a common textbook example of a circuit with inductance. Introduction A coil is a common electrical component that provides inductance in circuits. 2dB (at the power level) Configuration of the circuitry ranges from 50Hz to 1kHz . Adequate trace width is necessary to ensure the desired amount of current can be transported without overheating and damaging your board. In terms of how these calculators work, the impedance of a transmission line in a PCB can be calculated in four ways: Use the R, L, C, G parameters from the Telegrapher’s equations to calculate the impedance of the transmission line. Now add a second trace in parallel (connected at each end) of the same length and dimensions, such that it also has the same inductance x x. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. Figure 2: Types of via holes (Source: Altium). Always consult PCB design guidelines for accurate. R 50Ω R 50Ω RM VS LM VS VI V=L V=IR d dT Scope Input I Figure 7. Tech Consultant Zach Peterson explores a very common issue in PCB Design: Trace Inductance and when to make traces wider. e. inductance per unit length: Z c [Ohm] effective characteristic impedance: t' pd [s/m]Advanced Circuits has been the leading PCB quick turn manufacturer since 1989. 08 mm) for 5A. Just like this foil inductor, your transmission lines have some loop inductance. Color-Code. Use our free online coil inductance. How can PCB trace inductance be. 19 INDUCTANCE 12. 44 x A0. One challenge in designing PCB interconnects is maintaining system impedance while reducing crosstalk, which requires reducing trace inductance. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . The spacing between traces is 45nm as well (and the thickness of the metal layer is 45nm). Calculates the characteristic impedance and per-unit-length parameters. Capacitance = ϵ ∗ Area/DielectricThickness C a p a c i t a n c e = ϵ ∗ A r e a / D i e l e c t r i c T h i c k n e s s. This can be set to zero, but the calculated loss will not include conductor losses. This calculator finds both odd and even transmission line impedance. The spiral Inductor is a two port multiturn planar inductor with multiple dielectric layers. 378 [mils/oz/ft2]) (I) Then, calculate the maximum current: IMAX = (k · TRISEb) · Ac (II) Where: A is the cross-section area [mils 2 ] T is the trace thickness [oz/ft 2 ] W is the trace width [mils] I MAX is the maximum current [A] T RISE. This shows that widening a trace will reduce the inductance of the trace. Permeability (µ) is assumed to be 1. For a stripline, where the electric (and magnetic) fields are in a uniform substrate, dielectric constant εr, equation (9) becomes cC Z r ε 0 = (10) where c is the velocity of light in vacuuo (or free-space). 0035 cm. Note: The results are only for approximation and rough estimation, the final values and the. Using the example numbers: L = 20 x 10^-3 * 12 x 10^-12 = 240 x 10^-15 henries or 0. This gives the PCB fab houses a bigger ring to drill through the middle of, thus decreasing the chances the your board will be fabricated with errors. h is the height of the via. The inductance allows one to understand the amount of energy that can be stored in magnetic fields. 8mm (0. 20) Resistor Color Code calculator. Relative Permeability is assumed to be 1. 24) Inductor Color Code Calculator. INTRODUCTION In the second part of this two part series on inductance calculation techniques, approximation techniques and handbook methods are shown for air-core structures that do not easily lend themselves to closed-form solutions. PCB spiral Coil. The equation is universal to microstrips, striplines, or any other pair of coupled lines with matching geometry. IPC 2221 calculator uses a single graph and an equation for determining the track current denoted by 1. So It is recommended to avoid trace widths less than 6mil, unless it's absolutely necessary.