PCB News - Exploration of Design Technology of High Power Circuit Board

Safety and will not interfere with other electronic equipment is the primary focus of the design of high-power PCB printed circuit boards. The so-called safety includes that the circuit does not have the risk of burning and electric shock. In addition, it will not cause other circuits to malfunction or interfere with other electronic equipment in the same chassis. The normal action of the robot is also a basic item that must be paid attention to. Regarding safety and interference with other electronic equipment, in fact, UL and EMC specifications have detailed regulations. In order to comply with UL and EMC specifications, when designing printed circuit boards, it is necessary to fully grasp the details of the safety regulations, especially It is the malfunction of the circuit caused by noise, which causes frequent post-event countermeasures, which is often caused by the failure to conduct pre-review when designing the printing pattern. If the circuit design and the printed pattern design belong to different units, the circuit designer must communicate fully with the printed pattern designer in advance. Past experience shows that pattern designers simply follow common sense and often lead to serious design frustrations when interpreting items that are not explained in detail. In view of this, this article will discuss in depth the design techniques of high-power printed circuit boards.

Ten basic design essentials for high-power printed circuit boards
Avoid stretching the pattern, try to reduce excess copper foil

Cut excess copper foil
It is generally believed that the so-called pattern design is intuitively just a simple pattern layout. However, designing the pattern of a high-power printed circuit board is not a simple pattern layout. When a voltage is applied to the circuit, the interval between the patterns on the circuit board is designed, That is, how to reduce the excess copper foil is the main technique for designing high-power printed circuit boards.

Reduce pattern impedance
The main purpose of why the pattern is not laid is to reduce the impedance of the pattern. By reducing the excess copper foil, the width of the pattern becomes thicker, and the area of the copper foil becomes larger and the DC impedance becomes smaller. In addition, the area surrounding the pattern becomes smaller, the impedance of the relative pattern becomes smaller, and the impedance as a whole can be greatly reduced.

Design with stubby pattern
When compared with small-signal digital circuits, since high-power printed circuits target high voltages and large currents, it is necessary to fully grasp the characteristics of the circuit current to determine the width of the pattern.

Calculate the width of the pattern according to the current effective value
According to past experience, the allowable current per 1mm of the pattern width is about 1A. However, it must be noted that the above empirical value is applicable to DC power supplies with less current changes, such as switching power supplies, where current changes and peak currents are extremely large. For the circuit, if the above experience value is directly used, it will cause serious consequences such as malfunction and reduced efficiency. Since the current of the switching power supply flows into the circuit intermittently, the effective value of the current will be larger than the average value. At this time, the effective value of the current must be used to determine the width of the pattern. The effective value IRMS[ARMS] of the current waveform shown in Figure 1 is calculated according to formula (1) as 0.5ARMS, which means that the width of the pattern must be greater than 0.5mm.

The above is an introduction to the exploration of high-power circuit board design technology. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology.