The relevant FR4 material parameters are only different from polyimide by about 2%, so the IPC-2152 standards are equally applicable to PCBs on FR4. You cannot insert an arbitrary thermal conductivity value in the formula to determine the temperature rise for a given current capacity. Although the IPC-2221B results were originally defined based on data for polyimide boards, the results are still accurate for FR4 boards. If you search online, several designers have taken the time to summarize much of the IPC-2152 information into compact formulas and have built calculators that work with these formulas.įor simplicity, IPC-2152 formulas don’t account for the effect of the board material.
Working with a calculator can be a real time saver and can also prevent errors that can be made during manual calculations. I can’t count the number of times I have transposed or omitted digits when working with a handheld calculator. Online calculators vs handheld calculators Using an IPC-2152 Calculator For Design This is a great way to support the PCB design community and preserve your own sanity in the process. Anyone can obtain the IPC-2152 data and determine these formulas on their own.
Rather than peeling values off of a chart with imaging software or a ruler, you can directly calculate the appropriate trace area and current capacity for a given temperature rise. This is where an online calculator becomes a real time saver. Imaging software can be used to get an accurate value using pixel values between tick marks on a chart, but this time-consuming as you will need to measure pixel distances for every ordered pair on a chart. If you’ve ever tried to extract numerical results from a chart, you know that you will inevitably be forced to estimate. The standards also account for the distance between traces and copper planes, as well as buried and surface traces. The new IPC-2152 standard presents results that summarize how thermal conductivity, vias, board material, and thickness affect the relationship between current, trace cross-section, copper weight, and temperature. Given the number of layout possibilities in any given PCB, the original charts in IPC-2221B are not applicable to every design.
The relationship between temperature rise in a PCB, the current in the traces, and the cross-sectional area of the traces were summarized in a series of charts in the IPC-2221B standard. Calculatorsįirst some background: if you are familiar with the evolution of IPC standards, you may remember that the original trace design standards were based on 50-year-old experimental results on polyimide boards. While the standard is important for thermal management in PCBs, it wasn’t until recently that everyone agreed on the correct formula to use to size traces. Since 2009, the IPC-2152 standard became the prominent standard for sizing conductors on a PCB. While it may seem like a simple requirement, knowing the temperature rise and current carrying capacity in your PCB are outlined in the IPC standards for electronic devices. But even in this early stage, there has been little talk of designing the product according to industry standards. The visionaries abound and several talented people are working to make the devices into promising prototypes. I work with a hardware startup that is working on new light sources for microscopic imaging.