-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueSolder Printing
In this issue, we turn a discerning eye to solder paste printing. As apertures shrink, and the requirement for multiple thicknesses of paste on the same board becomes more commonplace, consistently and accurately applying paste becomes ever more challenging.
A Culture of Thriving
One cannot simply command thriving; it must be nurtured, developed, and encouraged. In this issue, we explore strategies to improve your working relationship model—both internally and externally. In this culture of thriving, your business will grow in the process.
Certifications
Certifications have historically been seen as a cost of doing business, but how do we turn them into a positive ROI and a value to both customer and vendor?
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
How to Streamline PCB Thermal Design
April 1, 2015 | John Parry, Mentor Graphics CorporationEstimated reading time: 2 minutes
![](https://iconnect007.com/application/files/4416/3116/3154/MentorGraphics1.jpg)
Thermal issues with a PCB design are mostly determined during the component selection and layout phases. After this point, only remedial actions are possible if components are found to run too hot. Addressing thermal issues early in PCB design, starting at the system or enclosure level to understand the flow environment critical for air-cooled electronics, can streamline the process. Assumptions about the airflow uniformity in early design that subsequently prove unachievable can have a disastrous effect on the commercial viability of the product and meeting the market window.
Begin Before Placement and Layout
Substantial work can be done well before layout is completed within the electrical design flow. A simple representation of the enclosure can provide information about the air flow profile over the board. Start by smearing the total board power over the total board surface, which will provide a temperature map that will show any hot regions that are caused by a badly distributed air flow. Treat the board as a block with an isotropic conductivity of between 5 W/mK and 10 W/mK to optimize enclosure-level air flow ahead of the PCB design.
Components inject heat locally into the board so the heat flux density into the board below a component will be higher than the average for the board. As a result, the local board temperature will be higher than that predicted in the simulation. Refine the model before using the board temperature to estimate component temperatures. If the board temperature at any point is close to the maximum component case temperature, this limit will be exceeded once the component heat sources are represented discretely.
Guesstimate Component Power
At this stage, make a best-guess estimate of the individual power budgets for the main heat dissipating components that will be used in the design and the approximate size of those packages. This will enable describing them as footprint heat sources in the simulation, smearing the remainder of heat uniformly over the board surface.
Before Selecting the Package, Use 3D Component Models
Include some form of 3D component model in the simulation before the component selection is finalized. By feeding the thermal results back before this milestone is reached, the thermal performance will more likely be considered in the package selection criteria. Some ICs are available in more than one package style, and not all package styles perform equally well from a thermal point of view. The need for a heatsink later may be eliminated by appropriate package selection.
Component temperature, either in the form of a case temperature or junction temperature depending on how the manufacturer has specified the component, is the key measure used to indicate whether the design is thermally acceptable.
Editor's Note: This article originally appeared in the March issue of SMT Magazine.
Suggested Items
I-Connect007 Editor's Choice: Five Must-Reads for the Week
09/06/2024 | Nolan Johnson, I-Connect007This week’s Top 5 starts with steps you can take to cultivate a culture of thriving. We also have bullish news from the global semiconductor sector, advice on how to tease out hidden cost drivers during the PCB design cycle, how the Altium-Ansys collaboration will affect design, and Happy Holden’s version of Occam’s Razor—three simple tools to keep your wet processes in line.
Impact of the Altium-Ansys Partnership on PCB Design
09/05/2024 | Josh Moore, AltiumThere’s a saying in electronics hardware design: “There are two types of electronics designers: those who have signal integrity problems and those who will.” This adage emphasizes the inevitability of encountering and the need to address signal integrity (SI) and power integrity (PI) issues.
Hidden Cost Drivers in PCB Design
09/05/2024 | Cherie Litson, CID+, Litson1 ConsultingI recently taught a CID+ course, and if you’ve ever taken a CID or CID+ course, you know that we discuss cost adders quite a bit. When I asked the class of 15 design engineers their ideas on the biggest cost adders, the first and strongest response: the project manager. Are you surprised by their answer? After over 40 years in the industry, I wasn’t. If you step back and look at the process of product development, you’ll see that many decisions that affect costs down the line really do take root with the project manager.
Altium, Mouser Team Up to Advance Electronics Education and Careers Worldwide
09/05/2024 | AltiumAltium LLC, a global leader in software and solutions for the electronics industry, and Mouser Electronics, a global authorized distributor of semiconductors and electronic components, are excited to announce a strategic partnership aimed at advancing electronics education and careers worldwide.
Young Professionals Spotlight: Process Engineer Kevin Dial, American Standard Circuits
09/05/2024 | Dan Beaulieu, D.B. Management GroupWhen I heard that my friends at American Standard Circuits had hired a new, fresh-out-of-college process engineer, I was anxious to meet him. Now, you get to read this interview. It’s a rare perspective of a young man new to our industry.