When looking for a skilled Printed Circuit Board (PCB) designer, it is important to ask the right interview questions to ensure you are finding the best candidate for the job. This blog post will offer a collection of questions that employers can use to determine an individual’s ability to complete PCB design tasks. Asking the right questions can help an employer gain a better understanding of the candidate’s proficiency in PCB design. The questions covered in this blog post are geared towards evaluating a candidate’s understanding of PCB design tools and processes, as well as their practical skills and experience with PCB design. Additionally, this post will provide employers with insight into the candidate’s knowledge of the industry and their commitment to the job.
How to Nail Any PCB Design Job Interview
If you are a skilled printed circuit board designer and an electronic technician, you are qualified to work for an electronic component manufacturer. You can browse the www to look for relevant jobs based on your qualifications and skill set. wisdomjobs. com. You can find detailed information about all available jobs for printed circuit board designers here. You will be able to use computer programs as a printed circuit board designer to work on electronic components used in computers, smartphones, and other electronic devices. Browse the wisdomjobs page and submit an application to any of the reputable companies where your skills will be most useful. To prepare for the interview process, read the Printed Circuit Board Design job interview questions and answers.
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Everything is Embedded and Integrated
With today’s hardware, more crucial processing tasks are moving from your phone or the cloud to the end device. Basically, the trend that started in 2010—where everything was connected to your phone, laptop, and some online service—is being reversed. It just means that more of the application development effort is concentrated on the embedded side of the product, and the hardware must be designed to support this. Placing processing-intensive tasks on the end device does not mean a product will never connect to the internet.
Communicating with embedded developers will be easier if you have a basic understanding of languages like C and Python.
All of this means that a modern PCB designer must have a foundational understanding of programming and software development. Although you don’t have to be working at a professional polyglot software developer level, knowing the basics of software and programming makes you more valuable. Knowing a little bit of C, Python, or another language is always beneficial so that you can at least communicate with developers on their terms. Understanding small details like timing diagrams is helpful for communicating with developers even if you’re not the best coder. Working in a multifunctional team is an important skill to have whether you’re a contractor or looking for a full-time job.
PCB Design Interview Questions
The PCB material must be selected entirely based on balancing the demands of the design, volume production, and cost. Design demand is the term used to describe the electrical components that must be considered when designing high-speed PCBs. Calculating the dielectric constant and dielectric loss also requires consideration of the frequency.
2: How can high-frequency interference be avoided?
Reduced crosstalk can be achieved by increasing the distance between high-speed signals and analogue signals, or by using ground guard or shunt traces alongside analogue channels, which is the most effective strategy for combating high-frequency interference. Additionally, it is necessary to consider the noise interference caused by digital ground on analog ground.
The following two considerations should be made when designing traces for differential signals: On the one hand, the distance between two lines should remain parallel, while on the other, the length of the two lines should be equal.
The signal sources and the receiving end must both be differential signals for traces carrying differential signals to function. As a result, clock signals with a single output end cannot be routed differentially.
5 . Is matching resistance able to be applied between differential pairs at the receiving end?
Between differential pairs, matched resistance is frequently applied at the receiving end. matching resistance is usually used.
Differential pair traces ought to be parallel and closely spaced from one another. The distance between differential pair traces is determined by differential impedance, a crucial reference parameter in differential pair design.
The majority of automatic routers now allow you to specify constraint constraints to control how you run your wires and how many holes you have. All EDA vendors differ significantly in terms of wire running methodologies and constraint condition setup. The difficulty of autonomous routing is closely correlated with the ability to run wires. Consequently, this problem can be solved by getting a router with a high throughput.
Copper covering is generally firmly attached to the ground in empty spaces. It is important to carefully calculate the distance between copper coating and signal lines because coated copper slightly reduces characteristic impedance. In the interim, other layers’ characteristic impedance shouldn’t be changed.
Of course. For the purpose of calculating characteristic impedance, both the power plane and the ground plane can serve as reference planes.
Whether test point regulations are consistent with test machine requirements will depend on the circumstances. Additionally, it may not be possible to place test points on each line segment if routing is done too meticulously and test point restrictions are too strict. Of course, manual methods can be used in addition to test points.
Everything is dependent on the circumstances, including the test point addition method and the signal running speed. By joining them to lines or removing a segment, test points can be added.
Kirchoff’s current law states that whenever power or signals are transferred from Board A to Board B, an equal amount of current is returned to Board A from the ground plane, and the ground plane’s current flows back at the path with the lowest impedance. Therefore, in order to reduce ground impedance and noise, the number of pins contributing to the ground plane at each interface of power or signal connectivity should never be too low. The entire current loop should also be examined, especially the region with the highest current and the ground plane connection.
13: Is it possible to add ground lines in the middle of differential signal lines?
Ground lines cannot be added to differential signal lines because the most crucial aspect of the differential signal line principle is the benefit of mutual coupling between differential signal lines, such as flux cancellation and noise immunity. The coupling effect will be eliminated if ground lines are inserted between them.
The goal is to use chassis ground to direct the path of returning current and to provide a low-impedance conduit for it. For instance, connecting the ground plane to a high-frequency component or clock generator is frequently done using screws. I wanted to keep the overall current loop area as small as possible. e. to reduce electromagnetic interference.
The steps listed below should be carried out in the proper order when it comes to digital circuits. To begin with, it is important to confirm that all power levels meet the design requirement on average. Second, check that all clock signal frequencies are operational and that the edge is free of non-monotonic problems. Third, confirmation of reset signals is required in order to comply with the standard. If the foregoing is accurate, the chip ought to send signals during the first cycle. Debugging will then be done utilizing the bus protocol and the system operating protocol.
Since crosstalk interference has a significant impact on timing and signal integrity, it should receive special consideration when designing high-speed and high-density PCBs. There are a few design options presented. First, continuity and matching should be controlled for the routing characteristic impedance. Second, note the spacing, which is typically twice as wide as the line. Third, the appropriate termination mechanisms should be chosen. Fourth, routing in various directions in adjacent levels should be done. Fifth, to expand route space, blind/buried vias might be used. To minimize the impact on timing and signal integrity, differential and common-mode termination should also be maintained.
17 . The LC circuit is frequently used to filter the wave at analog power. Why is it that LC sometimes outperforms RC?.
It’s important to think about whether the frequency band and inductance are properly chosen when comparing LC with RC. If the noise frequency of the power is too low and the inductance isn’t high enough, LC performs worse than RC because inductance reactance is connected with inductance and frequency. However, one drawback of RC is that the resistor is inefficient and uses a lot of energy.
EMC drives up the cost of a PCB board primarily because shielding stress is increased by increasing layer count, and some components, like ferrite beads or chokes, are designed to block high-frequency harmonic wave components. To satisfy EMC requirements, other shielding components on other systems should also be used. To start, it is best to use as many components with a low slew rate as you can to lessen the high-frequency sections that signals create. Second, external connectors and high-frequency components should never be installed too closely together. Third, to minimize high-frequency reflection and radiation, high-speed signals’ impedance matching, routing layer, and return current channel should be carefully planned.
Because noise is produced at power and ground when high and low potentials are switched, and because the amount of noise is inversely correlated with signal speed and current, it is necessary to separate digital and analogue modules. Even though analogue and digital signals do not overlap, if analogue and digital modules are not separated, the noise produced by the digital module is greater, and the circuit at the analogue region is similar, the analogue signals will be affected by noise.
20. How should impedance matching be implemented when designing high-speed PCBs?.
The importance of impedance matching in high-speed PCB design cannot be overstated. The absolute relationship between impedance and routing can be found in impedance, making it one of the most crucial factors. For instance, the distance between the reference layer and the microstrip or stripline/double stripline layer, the routing width, the PCB material, and other variables all affect characteristic impedance. In other words, until the circuit is routed, characteristic impedance cannot be determined. Preventing impedance discontinuity as much as you can is the key solution to this issue.
21. Which EMC/EMI mitigation techniques should be used when designing high-speed PCBs?
Typically, when designing EMI/EMC systems, both conducted and radiated components should be taken into account. While the latter belongs to the portion with a lower frequency (less than 30MHz), the former belongs to the segment with a higher frequency (greater than 30MHz). Therefore, it is important to note both the high-frequency and low-frequency components of the signal. Consideration should be given to component placement, PCB stack up, routing, component selection, and other EMI/EMC design elements. Costs are likely to rise if such factors are ignored. For instance, the external connector should be kept as far away from the clock generator as is practical. Furthermore, it’s important to carefully select the connecting points between the PCB and the chassis.
22. What is the topology of a routing network?
Routing topology, also known as routing order, refers to the order of routing in a network with numerous terminators.
23. What modifications to the routing topology are necessary to enhance signal integrity?
Due to the complexity of this type of network signal, the topology varies according to the signal’s direction, strength, and type. It is difficult to determine which signals are good for signal quality as a result.
24 What is the significance of copper coating?
Copper plating is frequently done for a couple of reasons. To start, a thick layer of ground or power copper will act as a shield, and some unique grounds, like PGND, can act as a protective ground. Second, to assure superior electroplating or stop lamination performance. To prevent deformation, copper should be coated on PCB boards with minimal routing. Third, signal integrity necessitates the use of copper covering. DC network routing for high-frequency digital signals should be minimized and have a complete return path. Thermal dissipation should also be taken into account.
25. What is the definition of return current?
High-speed digital signals travel along a PCB transmission line from drivers to carriers before taking the shortest route possible along ground or power to return to the driver terminal. Signals that return to power or ground are referred to as return current.
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FAQ
What are the interview questions for PCB design engineer?
- Are you familiar with the IPC-9351 standard?
- What are the most important skills for a PCB designer?
- How do you troubleshoot problems with a PCB design?
- What has your experience been with PCB design software?
What are the basics of PCB design?
Create and review schematics in accordance with engineering requirements after understanding the PCB Design Workflow. Make a blank PCB, the stackup, and the design guidelines. Add component information from the schematics to the new PCB design. To make sure the engineering requirements are met, place the components and check their placement.
What are the 3 types of PCB?
- Single-Sided PCBs.
- Double-Sided PCBs.
- Multilayer PCBs.
- Rigid PCBs.
- Flex PCBs.
- Rigid-Flex PCBs.
Which tool is used in PCB designing?
The majority of PCB design tools include CAD software, electronic software for Gerber and Excellon files, and the Internet for locating the best places to buy your components. Other materials, such as stencils and soldering equipment, can be referred to as “physical tools.”
