Happy’s Tech Talk #37: New Ultra HDI Materials
It’s Only Common Sense: When Data Isn’t Enough, Trust Your Gut
Marcy’s Musings: Fueling the Workforce Pipeline
How to Streamline PCB Thermal Design
April 1, 2015 | John Parry, Mentor Graphics CorporationEstimated reading time: 2 minutes
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.
Share on:
Suggested Items
Flexible Thinking: Mind-tapping into January
02/05/2025 | Joe Fjelstad -- Column: Flexible ThinkingIt’s January again, and our beleaguered planet has completed yet another trip around the sun. The Romans named January in honor of their god Janus, who is usually depicted as a bearded old man with two faces—one looking back to the past and the other looking forward to the future. People venerated Janus as the god of beginnings and endings, transitions, and the passage of time. With that in mind, I’ll look 10 years into the future—hopefully with a bit of inspiration from Janus—and prognosticate what might be happening in electronic design.
AMETEK Acquires Kern Microtechnik
02/04/2025 | PRNewswireAMETEK, Inc. announced the acquisition of Kern Microtechnik, a leading manufacturer of high-precision machining and optical inspection solutions.
ITW EAE to Showcase Latest Electronic Assembly Equipment Developments at IPC APEX
02/04/2025 | ITW EAEITW EAE will be showcasing its latest developments at IPC APEX, March 18 - 20 in Anaheim. The ITW EAE booth #2400 will have MPM, Camalot, Electrovert, Vitronics Soltec and Despatch Applications Experts on hand as well as Sales and Management to answer questions and offer solutions.
Building on DesignCon’s 30th Anniversary Momentum
02/04/2025 | Marcy LaRont, I-Connect007With three decades of technological advancements, DesignCon has established itself as a premier conference for electronics design. Susan Deffree, the group event coordinator, reflects on the event's rich history and the exciting developments for its 30th anniversary.
DesignCon 2025, Day 2: It’s All About AI
01/30/2025 | Marcy LaRont, I-Connect007It’s hard to get away from the topic of artificial intelligence, but why would you? It’s everywhere and in everything, and my time attending presentations about AI at DesignCon 2025 was well worth it. The conference’s agenda featured engaging presentations and discussions focused on the technological advancements in AI, big data centers, and memory innovations, emphasizing the critical relationship between processors and circuit boards.