8 PCB Design Interview Questions (With Example Answers)

Updated 20 March 2023

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Printed circuit boards (PCBs) are a medium which helps connect all components within an electronic gadget or appliance in a controlled manner. If you are planning a career as an electronic technician, you can expect some questions relating to PCB designing in your job interview. Exploring a few potential interview questions can help you prepare your responses better to deliver a confident performance in the interview. In this article, we list PCB design interview questions, discuss why interviewers ask them and share sample answers to help you understand how to prepare yours.

PCB Design Interview Questions And Sample Answers

Here are a few PCB design interview questions and their sample answers:

1. What do you need PCB?

When interviewing for the role of a PCB designer, the interviewer may expect you to have a basic understanding of why PCBs are essential for making functional and optimised electronics. You can answer this question by talking about the primary usage of a PCB and the functions it offers.

Example: "PCBs are the core components in cell phones, computers, laptops and almost every other electronic gadget. PCBs allow you to place components neatly without using wires or jumpers. PCBs support and connect the components electrically using conductive pathways, tracks or single traces moulded from copper sheets and laminated onto a non-conductive substrate. This is essential to control the electrical supply and consumption of the different components to ensure the device functions correctly. From an organisational perspective, PCBs allow the implementation of fully automated assembly processes, which reduces production time significantly."

2. Explain the flow of the complete PCB design

As a PCB designer, it is crucial for you to understand the design flow. The interviewer may confirm your understanding by asking you to explain the steps involved in PCB design. In your answer, talk about the steps included in designing a PCB. This can show the ability to design a PCB without errors.

Example: "The complete flow of designing a PCB includes steps like library creation, design rule settings, assembly settings, board outline and mechanicals, component placement, importing netlist, silk screen, Gerber settings, routing and split plans."

3. How do you plan routing, and what are the parameters you consider while routing?

By asking this question, the interviewer may try to learn about your overall design process. Routing is an important element of PCB design and a hiring manager might like to ensure that you have knowledge of the process. Explain briefly its importance and share some important tips to keep in mind when routing.

Example: "Placement routing is one of the most important steps when I design a PCB. The placement determines the quality of the board and I think that a good placement along with effective routing can reduce our fabrication cost significantly.

Usually, when I place components, I implement a routing strategy and follow a schematic flow. When I am done with the placement, I fan out all components and route the complex areas and high-speed interfaces first. In addition, for all the high-speed signals, I maintain a ground reference plane and ensure there is a reference plane for every trace. The reason I do that is that the signal's vias can change trace characteristic impedance."

4. If you wish to keep signal integrity under control, what are the design techniques you may require?

This question requires you to have a good understanding of design techniques. The interviewer expects you to talk about solutions to keep signal integrity under control. Your answer can show your ability to solve problems and come up with innovative solutions.

Example: "In my experience, excellent communication between the PCB designer, the EE design engineer, the manufacturing engineer and the test engineer is key to keeping signal integrity under control. As a PCB designer, I keep close coordination with the bare board vendor and the electronic manufacturing services (EMS) supplier. I receive good inputs from all of them and they add value to my design technique.

It is also very important to conduct digital simulation and EMI/EMC simulation. The faster you identify a potential problem, the sooner you can debug. This also usually means that there are fewer problems when you conduct compliance testing. This also means you can launch it quickly in the market."

5. Are there any mechanical issues in PCB?

Being aware of the mechanical issues for PCB can help you solve them and deliver good output. The hiring manager may ask this question to check whether you are aware of these issues and whether you might take the requisite steps to avoid them. In your answer, talk about some of these issues and steps briefly.

Example: "PCB has some mechanical issues that affect the assembly of the board. We can avoid these with proper measures. The foremost issue is the component size. If there is not a sufficient gap between the components during placement and it does not follow the datasheet, it can create issues. Another major issue is heat dissipation. If some components of PCB and RF generate heat, you can try to separate them from fluency components and low signal. In addition, you can also use a heat sink as a fix for the heat dissipated components.

In my experience, when designing a PCB, input and output are also very important. I prefer fixing the output and input connector before starting the design. Last, the mounting hole is another issue that is important to address. Without the mounting hole, it is not possible to fix it in housing or zig. Because of this, we ensure it is in the proper location and also ensure that the hole's size is as per the mechanical requirement of zig or fixing housing."

6. What are some of the parasitic issues in high-speed PCBs?

If you are applying for a senior role, it is likely that you may work on high-speed PCBs. The hiring manager can check your understanding of the tool by asking a technical question. Answer this question by mentioning some of the parasitic issues associated with high-speed PCB and how you might overcome the issues. For instance, you can discuss high-frequency circuits, shunt capacitance and inductive coupling.

Example: "High-speed PCBs are very critical to the design, as they completely depend on the placement and the routing of components. Until now, some of the parasitic issues I have come across in high-speed PCB are high-frequency circuits, inductive coupling, series inductance, shunt capacitance and capacitive coupling.

To overcome these issues, we can consider increasing the distance between conductors to provide a larger clearance, which eventually reduces parasitic capacitance. Other than that, we can be more mindful of the use of vias in our design, as an excessive amount can introduce a larger amount of parasitic capacitance."

7. Walk us through the steps of PCB fabrication

This question tries to assess how you can apply your knowledge of PCB design in a real-life situation. Answer this question in detail by talking about the steps you might take when fabricating a PCB. Try to keep the language simple and easy to understand to show you can explain technical details effectively when required.

Example: "The first step in fabricating a PCB is to refer to the Gerber provided by the PCB designer and generate the film. Next, I would select the raw material which the customer wants. It can be FR1 or FR4. After selecting the raw material, I might drill holes according to the Gerber data using a computerised numeric control (CNC) drilling machine and then apply copper to those drilling holes. After that, I select an area from the panel as per the Gerber data to take all film and apply photosensitive material.

The next step is to etch the exposed copper and tin to protect the copper circuit. I would do this after the film dries. With the help of a solder pad, I would then apply a solder mask to the entire board. The final step is to apply white letter marking through the silk screen printing process."

8. What steps do you take to ensure design compliance for EMI?

You might come across this question if the hiring manager wants to understand your design process and ability to solve problems. Talk about each of steps you can take for EMI design compliance. You can also discuss best practices and the process of testing in your answer.

Example: "I use cable connectors for all common mode chokes and ensure that we place the common mode chokes in proximity to the connector. It is also important that the ground and power planes are as close to each other as possible. When testing, the high-speed signal ideally refers to a power or ground plane and never crosses a split plane. If we use a split plane, I ensure that we also add a stitching capacitor."