For modern detonation systems, molded tantalum (MnO2) capacitors have two main advantages. Firstly, unlike aluminum electrolytic capacitors, they possess the high capacitance required by these small-scale systems. Secondly, unlike multilayer ceramic chip (MLCC) capacitors, tantalum capacitors are highly stable in performance under voltage, temperature, and mechanical stress.
Introduction
Detonation systems are crucial components in mining, demolition, and quarrying.
For decades, traditional detonators have been the preferred solution. Although these systems are reliable and relatively inexpensive, they have significant drawbacks, including long setup times and the potential to pose safety risks to users and manufacturers if deployed improperly. With the advancement of new technologies, electronic mining detonation systems have emerged, greatly reducing setup times and enhancing safety.
The next-generation detonation systems currently under development are equipped with wireless communication technologies that can be used by submarines hundreds of meters below the sea surface. These next-generation systems are no longer restricted by physical connections and can reliably transmit detonation signals wirelessly through rock, water, and air. Like any electronic device, detonation systems require an internal power source to supply power to the system controller (MCU) and charge the ignition capacitor. To ensure correct timing and reliable detonation, capacitors are needed as energy storage devices for the detonation elements.
Compared with other capacitor technologies, molded tantalum (MnO2) capacitors can store charge (with low leakage current) and have a high energy density, making them an ideal choice for electronic detonation systems, allowing more time and releasing higher voltages to ensure correct detonation. For companies developing and manufacturing electronic detonation systems to meet the needs of mining applications, this article will introduce the advantages of tantalum capacitor technology.
Detonator Design
Modern electronic detonators include delay modules that are suitable for various explosive applications and can detonate precisely and consistently. With improved controllability, the safety of detonation at the optimal time is also enhanced accordingly. The simple structure of a wired electronic detonator is shown in the figure below.
Inside the delay module, the MCU transmits signals to each capacitor to trigger ignition.
Depending on the design, one or two energy storage capacitors can be used to provide ignition. Therefore, capacitors play an important role. However, there are various capacitor technologies. So, how should capacitors for electronic detonators be selected?
It is impractical to use bulky DC/DC converters to convert high voltages (28 V or higher) into low voltages (3.3 V to 5 V) for the operation of the MCU, and capacitors are the ideal choice. Due to issues such as size, cost, and/or stability, technologies like aluminum, film, high-current power film, and liquid tantalum are not the best options. Therefore, we recommend two capacitor technologies: solid tantalum or multilayer ceramic chip (MLCC) capacitors.
However, although MLCCs have a variety of capacitance values and are small in size, their capacitance-voltage (CV) volumetric efficiency is insufficient to support typical detonator applications.
In addition to having a high CV, the capacitance value of tantalum capacitors remains stable throughout the entire operating voltage and operating temperature range, which means that the DC voltage output is consistent. Tantalum capacitors also have strong resistance to mechanical shock. Finally, low leakage current (DCL) is another characteristic that makes tantalum capacitors an ideal choice.
In contrast, in a 12 V application, the leakage current of MLCCs is almost twice that of equivalent tantalum capacitors, depending on the materials and capacities. Taking a 25 V, 22 μF capacitor as an example, which is the maximum CV that MLCCs can achieve, according to Ohm's law, DCL(I) = V / IR (R).
MLCC performance is as follows:
The insulation resistance (R) of MLCC: 50 ΩF ÷ (22 x 10-6F) = 2.27 MΩ
DCL(I) = V / IR (R) = 12 V ÷ 2.27 MΩ = ~ 5.2 μA
Low leakage current tantalum capacitor:
DCL(I) = 0.005CV = 0.005 x 12 V x (22 x 10-6F) = 1.3 μA
These calculations are based on the properties of commercial materials with an insulation resistance ranging from 50 ΩF to 1000 Ω*F.
UF Capacitors supplies high-performance tantalum capacitors that can be applied to electronic detonator products for precise blasting.
For inquiries, please contact: carey@ufcapacitors.com
Website: www.ufcapacitors.com