Both of my grandfathers served in the military. One in the Army and one in the Navy. I am tremendously proud of them for this. I remember well when one of them was struggling with cancer, he insisted on going to the Veteran’s Administration (VA) hospital. In those days, VA hospitals set the standard for medical care and had the most advanced medical equipment. Today, advanced medical equipment can be found in various medical facilities, which includes clinics, physician's offices, research labs, and universities.
Medical testing equipment
The proliferation of medical equipment is due, in large part, to advances in medical technology as well as the methods and tools used to design and manufacture medical electronic devices. One area that has benefited greatly is diagnostic and test equipment, which are virtually all comprised of electronic devices and PCBs. Today, these systems are smaller, faster, and more accurate than their predecessors due to the smaller, more precise and capable boards that drive them. Building these boards requires adhering to strict regulatory control and a design strategy that includes manufacturing concerns. Let’s take a look at the manufacturing considerations and how to incorporate them into your design of medical electronic devices.
Considerations for Medical Electronic Devices Manufacturing
There are more than 1,700 different medical device types in the FDA database, All medical devices, including electronic, must be listed here and classified according to usage and safety concern. However, some manufacturing concerns are board-specific. For example, flex and rigid-flex PCBs face specific issues that must be addressed during board construction. Nevertheless, we can explore the manufacturing considerations by looking at a common medical equipment type, a magnetic resonance imaging or MRI machine, that consists of several types of PCBs. In the figure below, a general diagram of the key electronic elements for an MRI is shown.
MRI electronics diagram
As shown in the diagram above, several types of PCBs are required for MRI machines. These include high-speed for the RF signal, which can extend up to 300MHz, processing and imaging, complex for the processor and data storage, and high power to drive the coils and amplifiers. In addition to these, the system has a power supply and most likely utilizes a dedicated power distribution (PDN) board. Manufacturing considerations for these board types are as follows:
- High-speed - The primary concern for high-speed boards is a constant impedance on the traces.
- High density - This is usually accompanied by compact, which means small multilayer boards. For these boards via types is a major consideration, as is the size and location of other drill holes.
- High power - Boards with high power present routing issues, as the high currents require heavy copper or wide traces. This can also present thermal issues as board temperatures may be excessive.
- Complex PDN - Power distribution presents problems, especially when multiple rails are present. Grounding and plane separation for the stackup become very important in these cases.
Now, let’s see how these concerns impact your design decisions.
Design of Medical Electronic Devices for PCB Manufacturing
As described above, the boards that comprise medical electronic devices can present a number of concerns for PCB manufacturing. Fortunately, these can be successfully addressed during design, by doing the following:
For high-speed boards or boards with high-speed traces, you can use controlled impedance to manage signal integrity. Trace impedance can be controlled by your choices for length and copper weight.
Choosing via type(s) can be a challenge. However, to achieve a design that will aid your board build, you should follow the tips for via selection; beginning with simple is better than complex for manufacturing.
For high power boards, it is essential that you employ tips for your PCB layout that target manufacturing. This will ensure adequate numbers of layers and grounding are included for your power and signals. It is also important that you incorporate good thermal design solutions to ensure board temperature doesn’t exceed acceptable levels.
Distributing power is making sure that all PDN loads are satisfied. This requires coordination between your PCB layout and stackup trace; and plane separation is important.
When designing boards for medical electronic devices there are essential steps that should be followed to ensure that the fabrication and assembly of your PCB are incorporated into your design decisions. Tempo Automation is the industry leader for fast, precise, and high-quality PCB development. Our expertise includes building medical electronic device boards for major medical researchers and OEMs. We will put our services to work for you to ensure that your devices meet your design objectives and the regulatory requirements of the medical industry.
|Tempo's Advanced Custom PCB Manufacturing Service for Complex Medical Systems Development
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on incorporating manufacturing considerations into the design of medical electronic devices, contact us.