PCB Profiling

06 December 2010

PCB profiling
PCB profiling

Profiling and machining can be conducted during the manufacturing stages of printed circuit board production. It is most commonly associated with the final operations in the manufacturing cycle to define the board outline.

 Each board can have its own specific shape; some boards are produced with a combination of routing and V scoring. Machining the board is also conduced to form apertures and cut-outs in the board to allow final assembly and break out of the board after testing.

There are two forms of routing - CNC and manual pin routing. Each has its place in the fabrication process to define the board outline in small and large volume plants. Manual routing can be used to clean up the edges of panels in a multilayer operation and remove the epoxy flash after the pressing cycle.

Basically a routing tool is used to cut around a predefined pattern on the printed board. This is conducted on a machine which has been pre-programmed with data from the design files from the customer.

It is also possible to use a manual process to define the outline of the board. Pin routing is conducted using a template made of aluminum or glass reinforced laminate machined to the finished board dimensions. The board or boards up to four high are pinned to the template using the board tooling holes. The template is used to guide the package on a pilot pin while the router cuts around the board edge.

In the case of single sided boards in high volume most of the outline and the through holes would be punched. In small to medium volume a machining operation would be used as previously outlined.

Profiling in high volume can be conducted during the assembly stage after final testing of the product. In this case a solid board or multi panel is delivered to the customer for PCB assembly. There would be no edge features on the board, this can benefit the assembly operation and reduce the price of the board or panel. The solid panel is easier to support during the assembly steps of printing, placement and reflow due to improved rigidity. There is also a benefit to board for wave soldering as solder does not penetrate through the routed sections.

After final testing the individual boards can be routed from the process panel just like the steps in the fabrication process with suitable extraction to remove the glass fibre residues. Generally this is for high volume applications or where there is concern about damage to components during board break out. Singulation of individual boards can be also be conducted by laser, water jet cutting and pressing but is dependent on the type and thickness of the laminate.

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