How to Choose PCB Components

May 15, 2019
How to Choose PCB Components

Deciding on which PCB components to go with can be a challenging task, as there are a wide array of different options to choose from. From component footprint decisions to checking spare gates, there are several different factors that need to be strongly considered before you decide on which printed circuit board component to go with. Here, we provide some tips or recommendations that you may want to consider before you decide on which PCB components to select for your business.

Consider Component Footprint

Here, we are referring to the layout phase, where land pattern and footprint decisions will need to be considered. In fact, you should think about the component footprint decisions throughout the drawing phase of the schematics involved. It is also important to note that the footprints will include both the mechanical components as well as the electrical pad connections of the part in question.

In other words, it will involve both the pins that affix to the printed circuit board as well as the body outline of the component. As such, when you are deciding on which component to select you should consider any packing or housing limitations that you may come across during the evaluation of the bottom and top sides of the finalized printed circuit board.

For instance, polarized capacitors and other such components often have height clearance limitations that need to be factored as part of the selection process of the unit. When you commence a design layout you may want to draw a rudimentary board outline shape and then place the connectors, or other such critically placed components, that you are thinking of utilizing. By doing so you will be able to create a virtual render of the PCB that is not only quick but will also not require any routing.

The resulting visualization can then be used to create a very accurate visual representation of the heights of the component and boards as well as their relative positioning. Then you will be able to ensure that all of the parts involved-such as the mechanical frame, chassis, and plastic-will fit inside of the packaging once the printed circuit board has been assembled.

Prepare for Changes

Your component choices may change as you go through various different designs. The design process is ever-changing, and you should consider which components will use surface plated technology and which components will be plated through-hole. By choosing which route to go with beforehand the entire planning process of your printed circuit board will become simplified. Power dissipation, component area density, the cost of components, as well as their availability, are all things that you need to strongly consider before deciding on which printed circuit board component to go with.

Generally speaking, surface mounted technology components tend to be easier to access and obtain than their plated through-hole component counterparts. Moreover, they also tend to be less expensive, at least from a manufacturing perspective, vis-a-vis their plated through-hole component brethren.

Interestingly, for medium and smaller prototyping tasks larger through-hole parts or surface mounted technology components are recommended in order to facilitate superior signal and pad access for debugging and troubleshooting tasks and they may also streamline the hand soldering process as well. It is also important to note that a customized footprint can be devised from within the tool in the event that a specific footprint cannot be obtained in the database.

Enforce Good Grounding Practices

The design that you incorporate should have an adequate amount of ground planes and bypass capacitors. In the event that you are working with ICs, you should make certain that you are utilizing the appropriate number of decoupling capacitors in close proximity to the supply of a ground plane or other such location.

Evidently, the capacitor size that you select will be largely determined by the frequencies that are involved, as well as the capacitor technology that is being implemented and the type of application. In sum, following good grounding practices is very important because it will allow your printed circuit boards to have optimized susceptibility performance as well as superior electromagnetic compliance.

Properly Assign Virtual Part Footprints

It is also highly recommended that you run a bill of materials, or BOM, in order to check for any virtual components. There are no footprints associated with virtual components and they will not be transferred to the layout phase either. By creating a bill of materials you will be able to able to assess all of the virtual parts on the design.

In terms of entries, you should only enter ground and power signals, as they are actually virtual components that are handled specifically in the schematic environment instead of the layout environment. In sum, components that are found in the virtual section should always be replaced by components that actually have footprints, unless they are being utilized for simulation reasons only.

Check the Spare Gates

In order to prevent the inputs from floating, all of your spare gates should have their inputs properly affixed to a signal. Unfortunately, gates can sometimes be omitted or forgotten, so you should take the time to inspect all of the forgotten or spare gates in order to ensure that any inputs that are unwired can be properly affixed if necessary. While rare, floating inputs can sometimes cause serious problems, such as causing the entire system to not operate as intended.

To learn more about choosing the right PCB Components, call Circuits Central at 888-821-7746 or contact us here.

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