MEDICAL ELECTRONICS & DEVICES
THINK AHEAD THERMALLY
USA: 1.855.322.2843
EUROPE: 39.051.764002
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Think Ahead Thermally - Medical
www.boydcorp.com/aavid
September 2016
Thinking Ahead Thermally:
A Guide to Thermal Management Considerations for Medical Devices
The medical device and engineering industry continues to grow and evolve year over year. As technology improves, the
population expands, and the depth and breadth of medical knowledge and treatments grow, so does our need for better
devices and equipment. As such, current trends that span all industries, such as electronics getting smaller and more
powerful, as well as increased focus on improved customer experience, have greater implications and challenges for the
medical industry. Should a device fail, a patient’s well-being could be endangered. Additionally medical devices need to
be portable, costs need to be judiciously managed so that treatment can be made available to the populace, and
reliability is crucial.
Aavid has been designing and manufacturing thermal solutions
for over 50 years and has worked with medical design partners
across the globe ranging from large corporations to small
startups. In doing so, we have identified and assessed the
major design flaws that lead to poor thermal management
and product performance. Not planning for your thermal
solution can cost time, money, and resources as well as cause
a large amount of rework or even massive device failures.
Planning ahead during your initial product design to allow for
appropriate cooling will make a significant difference to your
device’s success. This paper evaluates key thermal
considerations to take into account during the development
process to ensure that your design is safe and effective.
Start with the End User in Mind
As with most electronics, the number one priority is the end user. This is especially true for the medical device and
equipment industry, as the health and safety of both caregivers and patients are at stake. Engineers must determine
exactly who will be using the device and how. Usage dictates requirements which heavily impact your thermal
management choices.
Questions to address:
Will the patient or caregiver be in in direct contact with the device? If so, will they be near enough to the heat source to
feel it?
This is perhaps the most obvious consideration. If they touch the device or are exposed to it while running will it be
uncomfortably hot or even burn them? Finding a safe heat dissipation path and moderating touch temperatures are
Estimated US Medical Electronics Growth in USD.
Image Source: Grand View Research, Inc. 2016
MEDICAL ELECTRONICS & DEVICES
THINK AHEAD THERMALLY
USA: 1.855.322.2843
EUROPE: 39.051.764002
ASIA: 86.21.6115.2000 x8122
imperative if the end user will be in close contact with the device. In these
cases, you will need to set your requirements to account for safety and comfort
rather than the device’s operating limits.
For example, if a device were to feature a power intensive sensor that comes
into proximity with the patient, heat pipes might be a requirement to quickly
and safely remove the heat from the device, even if the device itself can handle
the heat load.
For higher power electronics, no matter where the heat is being dissipated, one
must account for the user’s safety. If using an enclosure, heat must be
dissipated through one of the sides or through a heat exchanger. The user
should be prevented from contacting these surfaces by use of a guard that still
allows airflow but prevents wayward fingers from contact.
How often and for how long will the equipment be in use?
Equipment use must be carefully considered in conjunction with the device’s rejected heat. Devices that are used for
longer stretches of time or with more frequency will likely need more powerful cooling. Constant use devices are likely
going to need active thermal solutions as the device will consistently be generating heat with little to no cooldown
period. Devices used intermittently but often will have a very different set of thermal requirements; as will devices used
infrequently but with high heat loads that need to be cooled quickly.
With smaller heat loads, even if used regularly, a thermal mass might be all that is necessary to conduct the heat away
from the device and dissipate the heat slowly and naturally. If the heat load is considerable, the device will require a
more complex system to dissipate the heat as quickly as possible. High, instantaneous loads may be too much for a
typical thermal solution to handle before the device reaches maximum junction or case temperatures. Heat pipes or
higher power cooling systems, such as liquid solutions, may be required to safely dissipate these loads.
With intermittent use devices, frequency is also a key consideration. When a device is operated so frequently that it
does not have time to fully cool down
between uses, inconsistent power
dissipation must be taken into account. This
is when the heat essentially adds up over
time, causing a higher average operating
temperature than what the device should
be exposed to. These transient loads are
often overlooked in the design phase and
result in inadequate cooling. Additional
analysis may be required prior to solution
design and product layout if there is the
potential for high transient heat loads. The
final cooling solution may be drastically
different when these are taken into
account.
Fan with Finger Guard
0
1
2
3
4
5
6
7
8
0 5 10 15 20
Watts or K
Time
Example Temperature Rise Response to Transient Power Loads
Power
Temperature
Rise
Think Ahead Thermally - Medical
www.boydcorp.com/aavid
September 2016