Best Interview Questions & Answers for PCB Design Engineer.

In this tutorial, we are going to learn about Best Interview Questions & Answers for PCB Design Engineer.

In this tutorial, we are going to learn about Best Interview Questions & Answers for PCB Design Engineer.

1. What are the errors we got while importing net list?

Answer: – PCB footprint not found.

*Pins mismatch between symbol and footprint etc.

2. How do we verify schematic symbols or footprints?

Answer: – Cross verify with datasheets, print footprints and match with actual devices before production.

3. What are basic checks while laying out MCU based design?

Answer: – Power Path: Ensure that the power flow tracks have sufficient trace width. Oscillator circuit: – Ensure oscillator is placed near to MCU pins. Distance depends on specific MCU. It is done so that MCU receives stable oscillations without noise.

4. What are the inputs we need to design a PCB?

Answer: – We need schematic, BOM and net list from Hardware side and Board mechanicals from client example board outline, mounting holes etc.

*And another important thing that we need is PCB stack-up it is based on complexity of the board for example if we are using FPGA first we should etc. The color of the solder mask gives the board its appearance.

5. How do we define design rules?

Answer: – Design rules are nothing but creating trace-width, apacing, vias limitations. Generally we get trace width and spacing details from stack-up.

6. What is main reason behind PCB failure?

Answer:-

* Component Design Failure

* Incorrect placement of components

* Power failure

* Overheating due to lack of space on the PCB

7. Why are printed Circuit Boards green?

Answer: – It is due to the solder mask, which protects the copper circuits printed on the fiber glass core to prevent short circuits; soldering errors etc.The color of the solder mask gives, the board, its appearance.

8. What is DRC? What kind of DRC errors we fine in PCB Design?

Answer: – DRC stands for Design Rule Checking. A PCB should not have any electrical failure before we tape out for the manufacturing. Common DRC errors include, trace to pad violation, pad to pad violation, component keep out violation.

9. What is the difference between a blind and buried via?

Answer: – Blind vias are used to connect an inner layer to either the top or bottom layer. A buried via is used for connecting two inner layers. It does not go either to the top or the bottom layer. A regular via (different from the blind and the buried via) connects the top and the bottom layer and also passes through the inner layers.

10. Which PCB/CAD tools do free Dom CAD use for layout?

Answer: – Cadence Allegro: – We have extensive experience with the cadence Allegro tool suite: we currently support versions 15 and 16. We are proud to be one of a handful or Early Adopter program members with Cadence.

11. What is the standard PCB thickness?

Answer: – Now days, boards are made to be larger and smaller than this standard, but the standard probably remains the most common thickness for designs. Today, it is more accurate to say there is a range of common or standard PCB thickness. These include 0.03in (0.78), 0.062in (1.57mm) and 0.093in (2.36mm).

12. What is the use of a decoupling capacitor?

Answer: – A decoupling capacitor is used to smoothen the power supply noise. It should be placed as close to the ICs for which it intended as possible.

13. What material is used in PCB?

Answer: – Printed circuit boards (PCBs) are usually a flat laminated composite made from non-conductive substrate materials with layers of copper circuitry buried internally or on the external surfaces. They can be as simple as one or two layers of copper, or in high density applications they can have fifty layers or more.

14. What FR4 is used in PCB?

Answer: – FR4 is the most used material in PCB construction. Boards made from FR4 are strong, water resistant, and provide good insulation between copper layers that minimize interference and supports good signal integrity.

15. Who invented PCB board?

Answer: – Paul Eisner first developed the printed circuit board when he was working on a radio set in 1936.

16. What is the best PCB design software?

Answer: – Allegro Cadence: – Allegro cadence is a professional PCB design software that has a wide set of features.

 * PADS:- Among the more affordable solutions, PADS is one of the best PCB design software.

                        * OrCAD.

                        * Kicad.

                        * Altium Designer (PROTEL)

                        * Eagle.

                         * Easy Eda.

                          * Design Spark PCB.

17. What does FR4 stand for?

Answer: – FR-4 or FR4 is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fib rite glass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).

18. What is CTE in PCB?

Answer: – The coefficient of thermal expansion or CTS, is the rate of expansion of a PCB material as it heats up. CTE is expressed in parts per million (ppm) expanded for every degree Celsius that it is heated. The CTE of a substrate is usually much higher than copper, which can cause interconnection issues as a PCB is heated.

19. What is PCB diagram?

Answer: – A PCB schematic is a simple 2-D circuit design showing the functionality and connectivity between different components. Initially blueprint has been completed, and then PCB design comes next. The design is the layout, or physical representation of the PCB schematic and includes the copper track and hole layout.

20. What is PCB fabrication process?

Answer: – PCB fabrication is the process or procedure that transforms a circuit board in design package into a physical structure based upon the specifications provided in the design package. Creating the PCB layer stack-up by laminating (heating and pressing) board materials at high temperatures. Drilling holes for mounting holes, through hole pins and vias. Etching or removing excess copper from the surface layer to reveal traces and pads.

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