Panelizing Aluminum PCBs: Methods and Challenges

Aluminum Printed circuit boards (PCBs) need to be kept secure during the manufacturing, shipping, and assembly processes to avoid damaging the unit.
 
Panelizing Aluminum PCBs is a way to safeguard their integrity.
 
In addition, panelization allows Aluminium PCB manufacturers to assemble multiple boards simultaneously, reducing costs and production time. Panelization must be done properly so that PCBs will not be broken or otherwise damaged during separation.
 
Following is a discussion of PCB panelization methods, as well as some challenges that may be encountered.
 
Methods:
 
1) Panelization
 
Panelization, also known as an array format, is used to process multiple boards while keeping them together in a single substrate. The process allows PCB manufacturers to maintain high quality while reducing costs.
 
The two most common methods of panelization are V-groove panelization and breakaway tab, or tab-route panelization.
 
V-Groove Panelization – This method involves cutting 1/3 the thickness of the board from both the top and bottom with a 30- to 45-degree circular cutting blade. The remaining board is quite sturdy and is depaneled by machine to avoid stress on the PCB. V-Groove panelization is used where there are no overhanging components.
 
Tab-Route Panelization This method permits placing PCBs of the same or different designs together. Space is left between the perforated tabs and the traces and surface mounted parts. This reduces surface stress and avoids splintering.
 
2) Depanelization
 
Depanelization is simply removing individual metal core PCBs from the array. Several different methods are used to depanel PCB arrays:
 
·Breaking by Hand – Only appropriate for strain-resistant circuits.
·Pizza Cutter – Used on V-grooves. Best for cutting very large panels into smaller ones, this method is inexpensive and low-maintenance.
·Punching – A two-part fixture punches out single PCBs. Higher capacity, but higher maintenance and cost.
·Depaneling Router – Single boards are connected using tabs; the router bit mills out the tabs. Can cut arcs and turn at sharp angles, but capacity is lower.
·Saw – Can perform at high feed rates, cutting both V-grooved and non-V-grooved PCBs.
·Laser – Low mechanical stress and precise tolerances, but has higher initial capital outlay.

Challenges:

Panelization presents a number of challenges in several areas:
 
1.Depanelization – disadvantages of some depanelization methods:
·Using a router could require additional cleaning prior to shipment. This method produces a lot of dust which must be vacuumed out.
·Saws can only cut in straight lines, so are appropriate only for certain arrays.
·Lasers should be used only with an optimal board thickness of 1 mm or less.
 
2.Overhanging parts – require pre-routing to avoid interference with depanelization:
·Components overhanging an edge can fall into adjacent parts.
·Overhanging components can be damaged by a saw blade or router during depaneling.
 
3.Incomplete data files – sometimes incomplete files are provided to the manufacturer, which can increase costs in several ways:
·“Breakaway holes” or “mouse bites” – These tiny holes permit small PCBs to be used in an array. Drilling these holes leaves rough edges. If the mouse bites are not shown in the data file, the unexpected extra work to remove the edges increases labor costs.
·Cumulative and registration tolerances – If tight tolerances are not specified in the data file, the cumulative effect of tiny variances could cause failure. With more boards in the array, registration can go off-center.
·Difficulty troubleshooting problems – Without complete data, issues such as a short during power ground short testing can be extremely difficult to trace back to their source.