The advance of modern medical devices is making medical service delivery super easy and comfortable. These modern medical devices are built on medical PCBs, thereby making medical PCBs super important in the medical field.This article will help you fully understand medical PCBs and the huge role they play in modern medical equipment. We will look at the meaning of medical PCB, its benefits, and the design and fabrication processes of medical PCB. We will further dive into the prototyping process of medical PCBs, their types, and applications.
Ready? Let’s dive in.
Medical PCB is a type of PCB used for making medical equipment and facilities. Because of the sensitivity of the medical field, medical equipment and facilities should be precise and accurate. This is mainly because the lives of people are at stake when these equipment and facilities are used on them. To have precise and accurate medical equipment, it needs to be built on accurate and highly reliable medical PCBs.
Below are some applications of medical PCBs in the medical field: Heart monitors, blood glucose monitors, blood pressure monitors, X-ray computed tomography, and heart pacemakers.
Benefits of Medical PCB
As we’ve already looked at, Medical PCBs are used for making various medical equipment and machines. This makes medical PCBs very important in the medical field. In this section, we want to look at some of the major benefits of medical PCB.
Smartphones, tablets, and watches have inbuilt capabilities that make it possible to measure people’s health status accurately.The availability of smartphones and IPad have made it super easy for medical officers to send and receive information.What’s more? You can order drugs with these smart devices. Medical officers can document drugs and conduct various medical research easily with smartphones and Ipads.
Figure 1. Blood pressure checking device
Health Record Management
The use of Medical PCBs in medical devices has allowed for easy record-keeping in the medical field. Before this, medical officers had to keep records manually and this slowed down patient treatment processes. This problem resulted in many deaths. But now, with the availability of electronic records, you can get records for important medical data with ease. This has helped fasten the medical service processes, thereby saving more lives.
With the availability of medical PCB-powered medical systems, you can send and receive important medical information more conveniently. This includes receiving lab tests results at the comfort of your home. This is possible because these medical systems use mobile devices and web-based applications. You can find nearby hospitals, pharmacies, and other medical facilities easily with these applications.
Medical PCBs ensure easy and faster production of medical drugs. This is because drugs are produced using the data of a particular group of people. Some medical devices help in collecting data easily for faster drug manufacturing.
Medical PCBs are used for making wearables that are used for accurate monitoring of the health status of users. These wearables can check various health conditions of users and give medical officers powerful information that helps them to treat users effectively.Athletes, footballers, and various sportsmen use different gadgets that track and record their motion, heart pulse rate, etc.
Figure 2. Tablet for Medical Research
How to Design and Fabricate Medical PCB
Medical PCBs should be carefully designed and fabricated to ensure it works perfectly. Various considerations should be made to ensure a high-quality, reliable, strong, and durable medical PCB.
Below are the step-by-step processes used for designing and fabricating a medical PCB.
Create Initial Schematic Design
Creating an initial schematic design is the first step of the design and the fabrication process of the medical PCB. Here, all the relevant information of the PCB is taken from the client and used to create a basic drawing. Some of the important details required here are the application of the PCB, type of PCB, power requirement, and material to be used. All these details must be accurate and used for the initial design of the medical PCB.
After the initial schematic design, the next step is to prepare a layout for the PCB. Here, you can upload the initial drawing on PCB software. The required details of the client should be added.
Consider and Add Crucial factors
To produce an accurate and effective Medical PCB, several critical factors need to be considered during the design stage. Some of these critical factors include the split planes, sequencing, and the number of pins, and their selection.
Split Power Properly
Splitting of power is done at this stage of the design process to ensure the level of noise and crosstalk are reduced in the board. This diversification of power should be done properly for effective results.
Allow Multiple Layers
To help reduce the level of SNR and noise, there is a need to have multiple layers for the PCB base. Multiple layers also make the medical PCB reliable and increase its performance.
Review BOM (BOM) List
The next step is to review the bill of material BOM for the medical PCB. The Bill of Material is a list that captures all the materials and parts of the Medical PCB.
To ensure the various parts of the medical PCB meet design requirements, they are checked thoroughly at this stage.
Prepare and Verify an Alternative Component Lists
Sometimes, certain components of the PCB may fail or fail to meet design requirements. To address this issue beforehand, a secondary list of components is prepared. This helps to save time in the designing process.
Make a Drawing for the Assembly
Assembling medical PCBs is a complicated process. In addition, since Medical PCBs are used for a sensitive medical field, they need to be very accurate. This means there should be no room for error when designing and assembling the PCB. To ensure the accuracy of the PCB assembly, a drawing of the assembling process is created and followed diligently.
Show Test Points in the Design
As said earlier, medical devices need to be accurate and precise since they work on the human body. This also means the Medical PCB used for making such devices must be accurate or free from errors. To achieve this, all possible test points should be shown during the design for efficient testing of the Pcb.
Medical PCB Prototyping
Before a medical PCB is produced in large quantities, there is the need to produce its prototype. The prototype helps the PCB manufacturer to predict the success of the board. Various functionality tests are done on the prototype to determine its shortfalls.
Figure 3. Medical PCB prototyping
With this, several designs and fabrication adjustments are done to produce a final PCB that meets the medical field’s standard requirements. This helps to avoid losses during mass production and makes the production cost-effective. Below are the processes involved in medical PCB prototyping.
● Creating a design for the medical PCB
● Drawing a schematic design for the PCB
● Create a routing design
● Create a Photo film
● Printing the inner layers of the board
● Fusing the layers
● Drilling holes
● Imaging of outer layers
● Copper Plating
● Tin Plating
● Applying solder mask
● Provide a surface finish
● Put on a silkscreen
Assembling Medical PCB
After designing and fabricating the PCB, the next step is the assembling of the PCB. During the PCB assembly process, various electronic components are soldered onto the fabricated board. This is done so that the PCB can function to achieve its intended purpose. This is because the fabricated PCB board by itself cannot perform its intended function.
Certain important factors need to be considered before starting the PCB assembling process. These vital factors include the type of circuit board, the characteristics of the PCB parts, and the function of the board.By then, before assembling, you need some vital tools to aid you in the process. Some of the vital assembling tools you would need include testing equipment, soldering machine, SMT equipment. Other important materials needed are solder wire and solder paste.
Due to the sensitive nature of the medical field, it is super important to conduct a design for manufacturability test before assembling the board. Design for manufacturability test is done to identify and correct any challenges with the design before starting the real assembling. The main goal of DFM is that the final medical board would function as required after the assembling.
Below are the assembling processes for the medical PCB:
Solder Paste Stencilling
The first step in the assembling process is solder paste stenciling. Here, a stencil is used to cover the board such that only the part that would be mounted with a component is left. This helps to apply the solder paste only at places where the components would be mounted.
To achieve this, the board and solder stencil is held in a mechanical fixture. The solder paste is then applied at designated places with an applicator. The solder paste is spread uniformly over the exposed areas. The stencil is then removed and the solder paste remains at the designated places.
Pick and Place
Here, the various electronic components of the medical PCB are mounted accurately. Due to the high accuracy needed for the assembling of medical PCB, a robotic device is used for this purpose. The robot picks surface mount devices and puts them on the board. The mounting device accurately places the components on the solder paste.
Soldering overflow is done to ensure the joints between the board and the electronic components are strong. To achieve this, the board is moved through a large reflow oven with the help of a conveyor belt. The solder paste is melted in the process by heating the PCB to about 2500°C. From the oven, the medical PCB is passed through coolers to solidify the solder paste thereby forming strong joints between the parts and board.
It is important to note that stenciling and reflowing of double-layered medical PCBs are done separately. The side with fewer and smaller electronic parts is done first.
Inspection and Quality Control
The assembled Medical PCB is inspected to detect and correct any flaws and connectivity issues that may have resulted from movements during the reflow. Some of the checks and inspections are done on the board include Manual Checks, X-ray Inspection, Automatic Optical Inspection.
Last Inspection and Functionality Test
The last step of the Medical PCB assembling process is to inspect and test the manufactured board. Here, a thorough functionality test is done to ensure the board performs as required and meets the high medical field standards. When the board is tested and approved, it is washed to remove oil, flux, and other dirt from it. This makes the medical board clean and suitable for making medical devices. Depending on the type of medical equipment that will make use of the Medical PCB, special tests can be done on the board.
Applications of Medical PCB
Medical PCBs have several applications in the medical field. Some of the applications of medical PCB includes:
● Internal medical devices
● Scanning technology
● Wireless Communication
● Scientific Instrumentation
● Control Systems
Figure 4. CT Scan
Types of Medical PCB
There are different types of Medical PCB. Depending on the type of application a specific type of medical PCB can be used. Let us look at the types of medical PCB.
Single Layer Medical PCBs
A single layer Medical PCB is the most basic form of all medical PCBs. It has one layer with all circuit components mounted on one side of the layer. A single layer medical PCB has one substrate layer that forms the main structure of the board. A copper layer is placed on top of the substrate layer. A silkscreen is placed on the board to capture vital details of the board.
To ensure the smooth flow of current through the board’s circuit, a solder mask is applied to the copper layer. These PCBs are common because they have lower production costs. They are used for making simple medical devices. A typical example of a single layer Medical PCB application in the medical field is the circuit of power sensors.
Double Layer Medical PCBs
Double layer Medical PCBs have two layers. Both sides of the layers are copper coated. Holes are made on both sides of the board so that you can mount electronic components on both sides.
Multiple Layer Medical PCBs
Multiple layer medical PCB has two or more layers. Each layer of the multilayer PCB is mounted with circuit parts. These medical PCBs have enough space on them and are relatively heavy. This makes it suitable for making complex and high-speed medical devices.
Rigid Medical PCB
Rigid Medical PCBs are produced with rigid materials. Because of this, you cannot bend their base. You can build several multi-faceted circuits from these PCBs. Rigid medical PCBs can be easily preserved when compared to other forms of PCBs.
Flexible Medical PCB
Flexible medical PCBs are made of a flexible material and hence their base can be bent. Flexible medical PCB comes in different forms. They can be single, double, and multi-layered, etc.
Rigid-Flex medical PCBs
Figure 5. Rigid-Flex Medical PCB
Rigid-flex medical PCBs are composed of both rigid and flexible PCBs. Depending on the application of the PCB, they are made of a certain number of flexible and rigid boards. Rigid-flex medical PCBs are most suitable because of their limited space usage and lightweight.
In this article, we looked at the meaning of medical PCBs, their benefits, and their design and fabrication processes. We further explored the prototyping process of medical PCBs, their types, and applications.
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