Board uniformity is the main concern in any printed circuit board manufacturing project. The boards that are non-uniform are discarded because they are not capable to meet requirements of an intended application. The production process for big and small remains the same, some changes are made during small PCB production to maintain their quality. PCB panelization is performed during the production of small circuit boards to ensure uniformity. In this method, various small sized circuit boards are pooled together to form a large panel. This helps manufacturers assemble multiple small PCB simultaneously. Thus, manufacturers can improve their productivity, as well as ensure uniformity, and quality of circuit boards. Panelization technique is also referred as an array format because multiple boards are kept together. PCB panelization allows designers to receive high-quality boards in big volumes. This post discusses everything you need to know about PCB panelization.
Important PCB Panelization Terms to Know
The following are a few popular panelization terms used by PCB manufacturers:
This technique is performed to remove PCBs from an array.
When several identical circuit boards are aligned next to each other in a layout, the resulting panel is known as a multiplier or a simple panel.
If several different boards are placed next to each other in a layout, it is referred as mixed multiplier, or complex panel.
This refers to a panel which is maximum processable. Many times, manufacturers use a same panel for developing circuit boards with same specifications. This helps them save on production costs.
Introduction to Different Types of PCB Panelization Methods
The printed circuit boards are panelized or routed using one of the following methods.
In this method, a printed circuit board is cut in 1/3rd thickness from top and bottom using a 30-45 degree blade in circular shape. The remaining board is depaneled using a machine. V-groove panelization is ideal, if there are no overhanging components. This method is ideal for scoring rectangular and square shaped PCBs. If your PCBs don’t have irregular or curved edges, then this method is not ideal. This method helps avoid stress on the PCB.
Tab Route Panelization
In this method, space is left between the traces, perforated tabs, and surface mounted components. Tab route panelization is performed on PCBs of the same or differing designs. It helps avoid chances of splintering, and minimizes surface stress. This method is not viable for heavy weight components like large relays or transformers. During tab separation, small laminate nubs may remain, which are usually sanded to achieve smooth PCB edges.
In this routing technique, small perforated holes are drilled in tabs. These perforated holes are sometimes known as mouse bites due to their smaller size. Small perforated holes make depanlization of individual PCBs a lot easier. In this method, additional material is left behind on edges, which may require sanding. As with tab route panelization, this method is not suitable for heavy components.
The best option depends on the dimensions of your printed circuit board or components, as well as the desired edge profile of the PCB. Now, we will discuss depanelization, and various PCB panelization guidelines that manufacturers should follow to avoid mistakes.
The panelization is performed to protect small boards during assembly process, and shipping. In the previous post we have discussed terms associated with panelization, and different processes. This post concentrates on the depanelization, and basic panelization guidelines.
Different Depaneling Techniques
The PCB arrays are depanelized before the final assembly or testing using any of the following methods:
Hand Breaking: As the name suggests, the operator can break the PCB along the prepared V-groove line using a proper fixture. Hand breaking is usually employed for strain resistant circuit boards.
Punching: In this process, single PCBs are punched out of the panel. A special 2-part fixture is used for the purpose. One part features blades, and the other features support. This method offers better throughput than other depaneling techniques.
Pizza Cutter/V-cut: In this process, a motor-driven blade is used to pre-scored PCB. The operator moves blade along the V-groove line. A special type of fixture is required for this technique. V-cutting is more appropriate for huge panels. Many manufacturers prefer this method over others because very low investment is required. Regular greasing and blade sharpening are the only requirements for maintaining the V-cut. The PCB is secured in place used an aluminum jig.
Saw: A saw is used to cut PCB in a straight line. This method is preferred if high-speed feed rates are required. It can be used to cut V-groove and non-V groove PCBs. Also, no dust is produced in this technique, as very less material is cut by a saw.
Router: In general, single boards are connected using tabs. These tabs are depanelled using a router. A lot of dust is produced during this routing process. Dust is removed by ESD safe vacuum machine. During the process, the PCB is held tight using an aluminum jig. The perfection of the process comes from – rotational speed, and feed rate. Both these are decided on the basis of the diameter, and the bit type. The router produces vibrations, which may not be ideal for vibration-free components on the PCB. This technique produces no straining.
Laser: This is the most advanced depaneling technique in this list. Nowadays, laser depaneling is performed using 355 nm UV, diode pumped Nd: YAG laser. This laser can efficiently cut through flex and rigid circuit substrates. Accurate tolerances and flexible cut capabilities make this routing popular among PCB manufacturers.
PCB Panelization Guidelines that PCB Designers Need to Follow
The following are a few common sense PCB processing array and edge guidelines that will help PCB designers minimize errors:
Add Processing Edges: Most PCB production machines are designed to process boards above 2ʺ conveyor width. If the rectangular PCB measures less than 2ʺ, then processing edges should be added to make it big or array of boards should be created.
Minimum Thickness for Rectangular and Non-rectangular Boards: Panelization can be performed for a simple rectangular board tab or a complex panel with routed or rounded polygons. If the PCB has rectangular edges, then all sides must have lengths greater than 1ʺ. The borders should be increased by 400 mil. Maintain 100 mil between same sized PCBs on a panel. If all sides measure length greater than 1ʺ, increase a 400 mil border in the outer side, and maintain 300 mil space between PCBs. If PCB is not of rectangular sides, then space between different PCB should be above 300 mil.
Clearance: The clearance between the PCB board edge and any metal should be minimum 20 mil for V-scoring and 5 mil for routing.
An experienced PCB manufacturer will always take the above guidelines into consideration to avoid problems. Working with a custom printed circuit board manufacturers like Twisted Traces will help you receive high-quality panelized PCBs, which meets the excellent industry standards.