PCB Component Placement Orientation Guidelines

Have you ever found yourself driving in the wrong direction on a one-way road because you were in an unfamiliar area? Unfortunately, there were several clues indicating that you were walking down the wrong side of the street, but you ignored them all.

The same is true when placing PCB components on our printed circuit board, which means that if we have components that aren’t aligned with the right orientation, there might be a lot of damage when it comes time to assemble the board. Fortunately, This FS Tech blog discusses some Tips & Tricks here in this article that will help to sort things out, beginning with some basic design consideration for manufacturability criteria of PCBAs. These standards will help ensure that your PCBAs can be manufactured successfully. Here is some further information on those criteria, as well as guidance on how to verify that PCB designs have the appropriate PCBA component orientation.

PCB component placement drawings
Reflection of predesign consideration for a PCB design Engineer

Considerations for Component Orientation on PCBs

You should bear in mind the three main aims that your turnkey PCBA assembly manufacturer will focus on while reviewing your design for manufacturability.

Standardisation of Assembly Methods

Your One-stop PCB manufacturer will always try to follow the Component assembly standards. Your cost of manufacturing PCB and PCBA can be reduced, as well as the amount of work and time required, if you ensure that the design of your printed circuit board (PCB) will be compatible with a standard assembly method.

Assembly Error Reduction

Your PCBA manufacturer will enhance production yields and once again pass on cost savings to you if they first address identified possible assembly concerns and then eliminate those PCB issues.

Quality Retention

Your Full turnkey PCB manufacturer has the ability to once again increase yields by locating components or materials that might potentially be faulty from the assembly process and replacing them with new ones. While designing a PCBA should take this information in account and select best components for your PCBA.

Taking this is article in depth, FS Tech Turnkey PCBA Assembly teams has narrowed down the main component placement Tips and Tricks for its clients. 

Placement orientation of various PCB components

An assembled PCBA board contains many electronic components including: IC, LED, Diode, Capacitor, etc. These different types of components have different placement rules. If there is a fatal mistake during assembly, you need to pay more for desoldering PCBA components. In order to avoid such errors, FS Technology provides several placement rules for components.

Capacitor Orientation and Placement

The direction of the capacitance on the PCB is what we need to pay attention to, it provides a role in coupling, bypassing, filtering, tuning loops, energy conversion, control, etc. The soldering method of chip capacitors is as follows:

  • When manually soldering chip capacitors, it is necessary to power on the soldering machine in advance and preheat the electric soldering iron.
  • Solder joints for resistors and capacitors are distinguished by white lines between the contacts. For large-capacity capacitors, it is necessary to distinguish the direction of the positive and negative poles, and the one marked with a dark straight line is the positive pole.
  • The position of the capacitor needs to be placed in the middle of the two solder joints. If a large deviation is found, re-melt the solder and adjust the position.
  • If possible, AOI inspection can be performed after welding to ensure that the solder joints and components are in the correct direction, otherwise manual visual inspection is performed.
  • By adding appropriate rosin to round the solder surface and beautify the solder joints.
  • Use high-purity alcohol to clean the PCBA surface, and prevent chemical corrosion from causing short circuits.
capacitor orientation on pcb
Small and Large capacitor placement in PCBA

When it comes to the location of Bypass and Decoupling capacitors, the golden rule is to keep the distance between the voltage pin of the component and the capacitor as short as possible. Because of this, you will need to position the decoupling capacitor in as close of proximity to the IC’s pin as is physically possible. When you are building a multilayer printed circuit board (PCBA), you should position the capacitor such that it is underneath the pad of the component. A capacitor is often positioned in close proximity to the pin on a single-layer design and connected to the pin via a short trace. If you need to position two capacitors, think about putting the large capacitance one farther from the IC to absorb the low-frequency power supply fluctuations, and the smaller capacitance one closer to the IC for the high-frequency ones.

LED Orientation and Placement

LED have always found their way into PCBAs, sometime there are used just for the indication of power ON status and sometimes there are used as identification of a process. The orientation of the leds on the pcb depends upon the function is going to perform. For example, if a LED is to be used for input power status, it is recommended to be placed near to input of power of PCBA like seen in some power adopter. As during operation, the LEDs can generate heat, you are advised not to place LEDs near to components which are sensitive to heat like many sensors are.

led orientation on pcb
Process indication LED placement on PCBA

When doing LED PCB assembly, LEDs are used for the process identification like charging status on a battery , in that scenario, LEDs are placed on outer edge of PCBA to make them come out of PCB enclosure. 

Diode Orientation and Placement

When it comes to providing a definitive indication of their polarity, diodes may be an especially challenging component. Diodes can be divided into patch diodes and plug-in diodes according to the assembly method, that is, the diodes are soldered to the circuit board using SMT assembly or DIP assembly. If you choose an assembly company that provides component sourcing services, you need to know what you need. It is helpful to have orientation information printed on the silkscreen of the printed circuit board (PCB), since this makes it more apparent throughout the assembly process. These devices may have a unidirectional or bidirectional character, but the bidirectional ones are the ones that are utilized the vast majority of the time. FS Tech suggests that designers position the TVS diodes in close proximity to the origin of the external signals that are being sent into the translator. In order for them to be as efficient as possible, they either need to be grounded through a plane, which is the optimum situation, or they need to have extremely short “stub” connections to their grounded side.


When creating component footprints for PCBs, it is in everyone’s best interest to keep the most recent datasheets and information on parts on available at all times. This will help prevent problems from occurring in PCBAs. You should also make use of the part-building wizards and utilities that are included in the design tools and software that you are working with. Many of today’s software also feature connections to internet library services, which provide users the ability to obtain information on various components, such as schematic symbols, PCB footprints, 3D step models, and more. You will be able to save a significant amount of time using these services in comparison to the amount of time you would have spent working at a library. Another advantage is that the majority of these models are supplied directly by the component manufacturers. This ensures that the components you use in your design will be of the highest quality.

Now that you know what to look out for when building a PCBA, try designing your own PCB business card yourself. Rewriting designs and replacing components, as needed, are regular tasks while working with PCBA. The PCBA business world works this way. Working with a partner like FS Tech that is experienced in PCBA testing, assembly, and production may save both time and money.

More related articles:

A collection of common PCB problems

PCB CAF Troubleshooting Guide

PCB short circuit analysis and prevention methods

PCBA fault analysis and defect resolution measures

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