With the rapid development of technology, the world we live in is gradually becoming digitized, thanks to the application of various types of sensors. As a sensing device, sensors can be used for real-time monitoring, measurement, and recording of specific physical quantities or environmental parameters, such as industrial, medical, military, environmental and other fields of monitoring, and are known as the Eye of the Internet of Things.
According to the different substrate materials, the sensors are divided into metal sensors, ceramic sensors and flexible sensors. In the production, thick film printing technology has been widely applied. Thick film printing technology is a key technology for producing thick film circuits, with a history of more than 50 years. It uses thick film screen printing technology and is sintered or baked in a high-temperature tunnel furnace. It has the advantages of density, sturdiness, and relatively low cost, and is widely used in fields such as automotive electronics, air conditioning, and missile navigation systems. Let's take a look at the specific application of thick film printing technology in sensor production together!
1. Metal sensors
A metal sensor is a device that utilizes the physical or chemical properties of metal materials to detect, measure, or respond to external environmental changes. These sensors can perceive specific physical quantities or environmental changes through the resistance, capacitance, magnetism, and other characteristics of metals. Metal sensors can be seen that common types of metal sensors include magnetic sensors, inductive sensors, capacitive sensors, resistive sensors, pressure sensors, and photosensitive sensors. In the production process, thick film screen printing technology can be used for printing protective coatings on all metal sensors and producing metal thick film pressure sensors.
(1). Metal sensor protective coating
After the production of metal sensors, it is usually necessary to print a protective layer to avoid external corrosion and isolate moisture. However, due to the small printing area and high film thickness requirements, many companies have repeatedly tried various printing methods such as inkjet and thick film screen printing during the experimental stage, but ultimately chose thick film screen printing. As a typeless printing method, inkjet printing uses an inkjet print head to directly spray onto the substrate and form an image on the surface of the substrate. But it requires high performance of the ink, so it is difficult to control the film thickness, and it cannot guarantee that the coating will not cause damage to the sensor surface. Thick film screen printing uses the force of a scraper to allow the paste to pass through the mesh holes of the screen and reach the surface of the substrate. As a relatively simple, low-cost, and batch printing technology, it can print various inks, pastes, adhesives, and glass glazes on substrates, with controllable printing accuracy and film thickness. The micrometer level film thickness achieves a protective and isolation effect without causing damage to the surface of the substrate. Therefore, thick film screen printing is currently the most practical and mature technology for printing sensor protective coatings.
(2).Metal thick film pressure sensor
Metal thick film pressure sensor is a type of sensor based on thick film printing technology. Its working principle mainly utilizes the piezoresistive effect of thick film resistance. When pressure is applied to a metal thin film, the film bends or deforms, causing changes in electrical properties such as resistance, capacitance, or inductance. During the preparation process, it is necessary to use a high-precision automatic alignment thick film printing machine to ensure printing accuracy and film thickness uniformity. As it is a metal substrate, it is necessary to first print an insulation layer (also known as a dielectric layer), and then print a resistance layer and a glass glaze protective layer.
2.Ceramic sensors
A ceramic sensor is a type of sensor made from ceramic materials as a substrate, used to detect and measure various physical or chemical quantities. Common ceramic sensors include ceramic pressure sensors, ceramic temperature sensors, ceramic acceleration sensors, ceramic humidity sensors, and ceramic oil level sensors. In the production process, thick film screen printing technology is mainly used for printing protective coatings and making ceramic thick film pressure sensors and automotive oil level sensors.
(1).Ceramic sensor protective coating
The printing purpose of ceramic sensor protective coating is the same as that of metal sensor protective coating, which is to protect the sensor from external corrosion and pollution. Unlike metal sensors, which typically print a layer covering the entire surface to be protected, ceramic sensors may also need to print a graphic protection layer corresponding to the sensor's graphics, requiring the use of an automatic alignment thick film printing machine for printing to ensure the accuracy of the overlay graphic position.
(2). Ceramic thick film pressure sensor
The process principle of ceramic thick film pressure sensor is consistent with that of metal thick film pressure sensor, but it has more advantages compared to metal thick film pressure sensor because the matching between ceramic substrate and slurry is higher, and the viscosity after sintering is better. However, the production process of ceramic substrates is complex and the cost is relatively high. During the preparation process, a high-precision automatic alignment thick film screen printing machine is required to print the electrode layer, resistance layer, and glass glaze protective layer, and each layer needs to be dried and sintered after printing.
(3). Automobile oil level sensor
A car oil level sensor is a sensor device used to detect and measure the oil level in the fuel tank of a vehicle. Its main function is to ensure that the driver is aware of the fuel level in the vehicle's fuel tank and provides accurate oil level information to the dashboard or vehicle control system. During the preparation process, a high-precision automatic alignment printing machine needs to be used to print the electrode layer, resistance layer, and protective layer separately, ensuring the accuracy of the printed graphics while also ensuring uniform line width.
3. flexible sensor
Flexible sensor refers to a type of sensor made by printing technology on a flexible material substrate.
Common flexible substrates include polyimide film (PI), polyester film (PET), etc. Due to its good toughness, ductility, and ability to bend freely, it can meet more application scenarios. Common flexible sensors include blood glucose meter test strip sensors, subcutaneous implantable blood glucose meter sensors, temperature sensors, pressure sensors, humidity sensors, and smart label sensors. Due to the fact that flexible sensors are a type of sensor made based on printing technology, thick film screen printing technology can be used for printing all types of flexible sensors. Such as common blood glucose meter test paper sensors and subcutaneous implantable blood glucose meter sensor conductive layer printing.
(1). Blood glucose meter test strip sensor
A blood glucose test strip sensor is a medical device used to measure blood glucose levels, used to measure blood glucose index. Mainly composed of substrate, electrode (carbon coating, silver coating), insulation coating, enzyme coating (enzyme, electronic medium, stabilizer), double-sided adhesive, hydrophilic film, and cover plate, high-precision automatic alignment thick film printing machine is required to print electrode layer, insulation coating, and enzyme coating on polyester film (PET) material.
(2). Subcutaneous implantable blood glucose sensor
Subcutaneous implantable blood glucose sensor, as a new type of blood glucose monitoring medical device, can continuously monitor blood glucose and transmit data to mobile phones by implanting micro sensors into the body. The thick film screen printing machine technology is mainly used to print the conductive layer of the electrode part of the probe that is truly implanted in subcutaneous tissue. The substrate material is generally polyimide film (PI).
In the specific application of high-precision thick film screen printing technology in sensor manufacturing, we have gained a deep understanding of the key role played by thick film screen printing technology in the preparation process of metal sensors, ceramic sensors, and flexible sensors. The widespread application of this technology enables sensors to play a more precise and reliable role in various fields. Overall, the specific application of high-precision thick film screen printing technology in sensor manufacturing provides reliable solutions for the production of various sensors, promoting continuous innovation in sensing technology in industrial, medical, military, and environmental fields.
