Single PCBs or PCB Arrays?
What are PCBs?
Printed circuit boards or ‘PCB’ is a non-conductive material with conductive lines that are printed or etched on them. The purpose of PCB is to serve as a platform to mount electronic components and the traces help guide the connection of components together to form a working circuit or an assembly.
Printed circuit boards are widely used to assemble today’s modern electronics. They involve a bundle of one or more insulating layers and one or more copper layers that contain the signal traces and the powers and grounds; the design of the layout of PCBs can be compared to that of the electrical circuit.
- Single Layer PCB – A single-layer PCB is a device that has a copper layer on one side of the board. This type of PCB has components on one side and the pattern to conduct electricity on the other side. A single layer PCB is useful for simpler electronic devices and is a cheaper option.
- Double Layer PCB – A double layer PCB has a copper layer on both sides of the board. This type of PCB has components and patterns on both sides of the boards. A double layer PCB is used on devices such as vending machines, phone systems, car dashboards, etc.
- Multi-Layer PCB – These types of PCB have more than three layers of copper. A multi-layer PCB is more durable than other types of PCB and is used on more complex devices like computers, phones, heart monitors, etc.
What is a PCB Array?
A PCB array means that many PCBs have been combined together to create a larger connected board. This is very helpful for manufacturers because this means a bigger board can be loaded into the machine instead of putting one PCB at a time. This can actually increase the rate of manufacturing. A PCB array design depends on various factors such as:
- Size – Depending on the number and size of PCBs that can be put into an array the size of array can vary. If small PCBs are attached then array will be smaller likewise if big PCBs are attached then array will be bigger. It also depends on number of PCBs attached in array.
- Rails – To make sure that people are comfortable using the PCB array we attach extra PCB material to the sides to make it easier to handle. You can choose to put the rails on 2 or 4 sides.
- Markers – Also known as fiducials they are used to ensure your assembly equipment aligns the boards properly. The standard procedure is to put three markers on the rails of the board but extra fiducials can also be added on the individual PCB to make the assembly process easier.
- Tooling Holes – These holes are placed in the corners of the arrays in the rails to make it easier to align the circuit board better. These holes are used to attach the board and are usually non-plated so that they don’t interfere with the electronic components in the PCB.
- Depanelization – An array can be depanelized to its individual PCB boards if it is ever needed. This depends on the method you choose to connect the boards together to make an array.
- Scoring – This means a V groove is put on opposite sides of the PCB array. Scorning is faster and makes the array more stable as well as takes less space between the PCB boards.
- Tab Routing – This is used to tab all sides of the array to panel it properly. Tab routing is easier to break apart into single PCBs and is great for more odd-shaped electronic devices. You can remove the PCB anytime using this method and it makes assembly easier.
Advantages of Using PCB Array
One of the main advantages of the PCB array is the increase in efficiency during the fabrication process. Rather than handling several individual small PCBs, the fabricator can operate on one large panel. This greatly improves the manufacturing process as the fabricator can make multiple boards in one sitting.
Another advantage of the PCB array is the ability to increase the efficiency of manufacturing large quantities of PCBs. Arrays allow manufacturers to load parts at a quicker rate as they can load a whole array of PCBs simultaneously as opposed to just loading them one at a time. The boards are loaded through the use of automation known as ‘pick and place’ machines. The machine simply picks up parts and place them down on the boards.
It is worth noting that arraying the boards will typically raise the cost of individual boards because fewer boards are produced on a production panel compared to just running as an individual board. Although you might see an increase in the cost of individual boards, the cost of assembling them will be decreased because of the array configuration.
Disadvantages of Using PCB Arrays
One of the main disadvantages of PCB arrays is the increment increase in the size of each individual PCBs. Although it is only a small increase in size, designers who will later utilize the individual PCBs will have to build their technology around the size of the finished PCB.
In order to join the PCBs together into a panel, manufacturers may use a process known as ‘tab routing’. In this process, space in between PCB is removed, leaving only a few small tabs to connect them. To separate the PCBs will require the breaking of the tabs, however, this will leave small edges which will require an additional process to smoothen them.
Depanelizing PCBs from an array requires a delicate process as it may lead to quality and functionality problems if it is removed too forcefully. Detaching a PCB from an array will impose physical stress on the PCB, which is why the designer will need to take into consideration spacing out critical areas of the circuit away from the breaking zone.
If this is not taken into consideration, it may result in the development of hairline cracks in the fine traces after the process of separation, and this can cause intermittent electrical operation.
Should You Choose Single PCB or Array?
The answer largely depends on the needs of your business as both single PCB and array serve their own purposes. Is your business trying to cut costs by producing large quantities of small PCBs with a low number of SMDs on each board? Or do you require individual PCBs that are very thin where using an array is not possible?
Choose the one which is most suited to increase manufacturing efficiency for your business.
