The Influence of Ambient Temperature on the Cooling Module

Article By : T-Global Technology Co. Ltd

Amid the ceaseless need for semiconductors in advanced applications across different industries, thermal management concerns are never far behind.

Something that doesn’t come as a shock to professionals in the semiconductor industry is change. Pursuant to what is now commonly known as Moore’s Law, based on an observation made in 1965, the number of transistors on an integrated circuit has doubled roughly every two years for more than 50 years. The sheer magnitude and variety of products that are pivotal to daily life today is a direct consequence of the never-ending technological advancement. With each passing year, semiconductors continue following the trend, in accordance with Moore’s Law, due to the demand for even smaller, lighter, and more powerful semiconductors.

Amid the ceaseless need for semiconductors in advanced applications across different industries, thermal management concerns are never far behind. If optimal semiconductor performance and reliability are desired, thermal management is an absolute necessity. A characteristic that is shared by semiconductors is that, while in operation, they produce a large amount of excess heat which, if left unmanaged, would diminish their performance. The management of said heat comes in the form of heat dissipation techniques, transferring the heat from the semiconductor and ultimately to the ambient environment. The crux of the matter is that with the ever-decreasing size of semiconductors comes an ever-increasing magnitude of heat flux densities that have to be contended with. That being said, design engineers in various industries will have to be innovative in the identification of thermal management solutions to resolve the thermal quandary associated with semiconductors.

“More Innovation. Less heat.” That is the most accurate summation of T-Global Technology’s ideology, which also happens to be the company’s slogan. It is an ethos that reverberates across the whole company in the provision of comprehensive thermal products and services, helping companies find the thermal solution(s) they’re in need of for current products, as well as technologies of the future. At T-Global, we have a complete production factory and R&D department located in Taiwan. We are committed to consistently exploring innumerable innovations for the purpose of keeping up with the rapid change in market and customer demands. We offer the total thermal solution for the customer in industries such as, but not limited to, information, communication, electronic, optronics, automotive, lighting, and medical devices. Not only do we have an experienced innovation and design team, but T-Global also provides customized design services to fit a customer’s specific needs.

It is worth mentioning that T-Global has already obtained ISO9001, ISO14001, and IECQ certification. Furthermore, with the high-quality product management and machinery, our products also obtained the RoHS, REACH and, UL certification, enabling T-Global to offer a wide range of high-quality, reliable thermal dissipation products. Said products include flexible absorbent material, thermoelectric cooling chips, heat sinks, thermal interface material, heat pipes, and vapor chambers, whose implementation depends on the customer’s needs. Another notable service is the thermal simulation. A thermal simulation helps T-Global’s R&D department identify the best way to resolve a customer’s heat dissipation needs. In cooperation with the Flotrend Corporation, T-Global is able to offer thermal management solutions to customers during a product’s initial conceptualization. This allows customers to then develop reliable products that will function without excessive and expensive aftercare. A brief explanation of how T-Global’s R&D department may utilize the thermal simulation service for the customer’s benefit is described below.

Assuming that a customer presents a heat dissipation problem as follows:

Figure 1: Customer’s product.

Figure 2: Cross-section of customer’s product.

Table 1: An example of customer specifications.

In this particular scenario, the customer would be in need of an analysis regarding their product’s heat dissipation capabilities. T-Global’s R&D department is well-equipped to offer such an analysis, an analysis that would involve:

  • Studying and understanding the parameters and specifications provided by the customer, as shown in the table above.
  • Investigate how the heat problem is or isn’t solved, upon receiving the customer’s model design (SolidWorks, STP, etc.), before T-Global makes any modifications. This allows the engineers to assess the possible routes that can be taken in order to reach a solution that will best satisfy the customer’s initial parameters.
  • Exploring the possible solutions and compiling a report to be presented to the customer, and offering the best recommendation for a way forward.

In the figure below, what can be seen is a result of a thermal simulation (using FloTherm XT) of the customer’s selected processor, assuming that no heat dissipation mechanism has been implemented. This allows the engineers to observe how well the customer’s heat dissipation solution would work (given the knowledge of the processor’s junction temperature when a thermal dissipation module has not been implemented) in a real-life setting, and whether it would satisfy the processor’s junction temperature requirements.

Figure 3: Processor (and PCB) temperature without a heat dissipation implementation.

Thereafter, a simulation of the customer’s complete product is then carried out, remembering to abide by the customer’s specifications. That particular simulation’s results are shown below.

Figure 4: Processor temperature with a heat dissipation implementation.

From the above results, the engineers make an analysis and make inferences, one of which would be the product’s case’s ability to absorb and dissipate heat to the surrounding air thus reducing the processors to 111.55 ⁰C from 202.54 ⁰C. In addition to that, the engineers can also identify why the customer’s design fails to work as desired (satisfying the processor’s maximum operating temperature parameter):

  • A notable shortcoming of this thermal dissipation problem is the customer’s stipulated ambient temperature. It is too close, in magnitude, to the processor’s (junction) maximum operating temperature. That small difference between the two temperatures, under natural convection conditions, is a hindrance to the customer’s product heat dissipation capabilities.
  • Another possible issue would be the use, and size, of the heat spreader. The heat spreader adds thermal resistance to the flow of heat from to processor to the fins located at the surface of the product’s cover. This means that a small amount of heat is transferred to fins, while most of the heat is absorbed by the PCB as well as the air circulating inside the customer’s product.

Having identified the aforementioned obstacles, possible solutions may then be contrived and explored. The heat spreader is explored first due to the stipulation made by the customer about the ambient temperature being a variable that cannot be changed. However, if need be, it can also be explored and recommendations can be made to customers.

As regards the heat spreader, two possible solutions are explored:

  1. Reducing the thickness of the heat spreader, and subsequently raising the PCB’s position to account for the proposed change.
  2. Foregoing the heat spreader altogether, and subsequently “dropping” the base of the central fins to account for the proposed change.

The relevant results are given below:

1.

Figure 5: Processor temperature with a modified heat spreader thickness.

 

2.

Figure 6: Processor temperature with no heat spreader.

The results shown above indicate that the modifications made to the heat spreader have little effect on the processor’s (junction) temperature. Furthermore, the results also suggest that the initial supposition regarding the relatively small difference between the ambient and junction temperature was, in fact, correct. This then prompts the exploration of the ambient temperature as a variable, as opposed to a constant. The expectation is that the junction temperature will show a more significant change once the ambient temperature is lowered, in contrast to the relatively small changes that have been observed up to this point. The results of the aforementioned investigation are given below.

Figure 7: Customer’s original design with ambient temperatures lower than 70°C: a.) 60°C, b.) 50°C and c.) 40°C.

Figure 8: Modified heat spreader thickness with ambient temperatures lower than 70°C: a.) 60°C, b.) 50°C and c.) 40°C.

Figure 9: No heat spreader modification with ambient temperatures lower than 70°C: a.) 60°C, b.) 50°C and c.) 40°C.

Table 2: Summary of thermal simulation results.

From these results, it can be observed lowering the ambient temperature allows for a larger temperature

gradient which, in turn, means that more heat can be transferred from the processor to the case and ultimately to the surrounding air. Furthermore, lowering the ambient temperature without any changes to the customer’s original product design results in a junction temperature that satisfies the processor’s operating requirements.

At this point, the engineers at T-Global will then compile a report detailing the results of the different thermal simulations and offer the best possible solution. The customer would be advised to reevaluate the conditions surrounding the initial ambient temperature specifications before sending their product to market.

For more information on how T-Global can help you solve your thermal dissipation predicament reliably, feel free to visit our website at https://www.tglobalcorp.com.

 

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