Project 2 - SiC/IGBT isolated gate driver reference design with thermal diode and sensing FET
- How will you decide the layer stack up.
Answer:
A stackup is the arrangement of layers of copper and insulators that make up a PCB before designing the final layout of the board. Stack-up refers to the arrangement of copper layers and insulating layers that make up a PCB prior to board layout design. While a layer stack-up allows you to get more circuitry on a single board through the various PCB board layers, the structure of PCB stack-up design confers many other advantages.Maintain a minimum distance between power and ground planes. Avoid placing two signal layers adjacent to each other. For such a designe a 4 or 6 stack layer will be chosen for the simplicity of the circuit and because the output delivered current is not of hight but ±10A drive strength for the gates of the IGBT .
2.How do you calculate the trace width, via size and trace length.
Ans:-
The important factors to consider when selecting a trace width include:
- The current capacity of the trace
- Space availability and manufacturing limitations
- Trace termination
- Impedance
Area [mils⊃2;] = (Current [Amps] / (k* (Temp_Rise [°C])^b))^ (1/c)
Width [mils] = Area [mils⊃2;]/ (Thickness [oz]*1.378 [mils/oz])
Then, the Width is calculated: Width[mils] = Area[mils⊃;2;] / ( Thickness[oz] * 1.378[mils/oz] ). how ever there are the Trance width could be calculated automaticaliy online after giving important parameters such as current, temperature, trace length. For this example we will assume the 6 layer stackup PCB with a thicknes of 1.6mm.
Absolute via sizes are not really specified according to industry standards. Instead, only the minimum sizes are specified based on the size of the component that will be mounted on the via. These standards must be followed if your PCB is to be compliant. The IPC-2222 standard specifies minimum hole diameters for plated through-hole vias for different classes of vias as follows:
- Minimum hole size = Maximum lead diameter + 0.25 mm (Level)
- Minimum hole size = Maximum lead diameter + 0.20 mm (Level B)
- Minimum hole size = Maximum lead diameter + 0.15 mm (Level C)
L = a + 2b + c
Propagation delay (t pd) = Trace Length / Signal Speed
Trace Length = Propagation delay * Signal Speed
where signal speed in a vacuum or through the air equals 85 picoseconds/inch (ps/in).
Propagation delay = 85 ps/in * sqrt(Er)
In addition to standard via sizes, there are also standardized pad sizes that should be used in compliant PCBs. The IPC-2221A standard defines minimum pad sizes for vias as a + 2b + c, where a is the maximum hole diameter, minimum annular ring size, and c is the fabrication tolerance. The fabrication tolerance depends on whether the vias are mechanically drilled or laser drilled, as well as individual process and machining parameters.The maximum fabrication tolerances are defined as 0.6 mm for Level A, 0.5 mm for Level B, and 0.4 mm for Level C. If the manufacturer’s tolerance is less than 0.4 mm, then the vias can meet the highest level of certification. Manufacturers usually have different processes that are designed to meet each level.Each of the levels above refers to a particular “density level.” Level A is used for boards component with low density and components with a large footprint. Level B is a standard density level that is suitable for reflow, wave, drag, or dip soldering. Finally, Level C is used for HDI board with very small, dense components.
3.What all you do to avoid heating of component in a 4 layer PCB.
Ans:-
4.Advantage of multilayer PCB?
Ans:-
Multilayer PCBs are the core of the assembly of modern devices. From a technical point of view, they possess several design advantages.
Small Size: The most prominent benefit of using multilayer PCBs is in their size. The layered design of multilayer PCBs is inherently smaller than other PCBs with identical functionality. This serves as a major benefit to modern electronics, as the current trend is headed towards smaller, more compact yet more power-packed gadgets like smartphones, laptops, tablets, and wearables.
Lightweight Construction: Smaller the size lesser the weight in PCB. In the case of single-layered and double-layered PCB, multiple connectors are required to interlink separate single and double-layered PCBs. This is eliminated in multilayered design making it more compact. Being compact in nature it becomes beneficial for modern electronics that is geared more toward mobility.
High-Quality: Due to the investment of more work and planning that has to go into the creation of multilayer PCBs, multilayer PCBs tend to be better in quality than single and double-layer PCBs. Due to the investment of more time and energy in the making of multilayer PCBs, these tend to be more reliable.
Increased Durability: Multilayer PCBs also come with high durability as they are capable to withstand the heat and pressure that is applied to them. Multilayer PCBs use multiple layers of insulation between circuit layers, binding it all together with a bonding agent and protective materials which just increases there durability.
Single Connection Point: Multilayered PCBs are beneficial for gadgets where size and weight are constraints. As they possess a single connection point they become compact.
Powerful: Multilayer PCBs mostly are high density and have a greater capacity as well as speed in comparison to other variants of PCBs.
Multilayer PCBs are highly useful due to these benefits in most of the devices especially mobile phones and high functioning electronics. With the new norm of high functionality and smaller size, multilayered PCBs are highly preferred in the market.
This is another reason adding functionality through additional layers is preferable to increase the dimensions of a single layer.but how ever Multilayer PCB boards manufacturing is more expensive as compared to double layer and single layer PCBs. Multilayer PCB board design is difficult so we need more time to work out any possible problems. They have a complex manufacturing process so there are high labor costs.