The V-scoring method has been used for many years in the production of printed circuit board (PCB). With PCB production technology evolving rapidly, it is important to be aware of the latest PCB scoring guidelines to follow and how they may differ from what you have used before.

The scoring process involves two blades that rotate closely together point-to-point as the PCB moves between the blades. The process is almost similar to slicing a pizza into a pancake, slicing the pizza into thin slices and then quickly moving the product to the next step, which can improve overall production. So when should you use scoring on your PCB? What are the potential drawbacks of this process?

Square printed circuit board

Whether your PCB is square or rectangular, all sides have straight lines and can be cut on a V-notch machine. The question to ask is, is it suitable for grading, or are there other areas that need to be addressed? To score or not to score? Here are a few reasons for refusing to answer.

Score thinner PCBS

Printed circuit boards thinner than 0.040 inches are difficult to notch for several reasons. A minimum of 0.012 “is required to secure the V-shaped coil, as the material (coil) notch blade left is set to simultaneously notch 0.010” – a depth of 0.012 “on both sides will make the 0.020” +/- 0.004 “net smaller than 0.040”.

Thinner printed circuit boards have some deflection only in the material. Flexible PCBS using the notched break method may leave rough edges and hang fibers. Controlling the scoring process with thinner materials and allowing significant interruptions is more difficult. The blade is critical to the tolerance setting of the depth of the notch from the top to the bottom, and there is a tighter range of accuracy to ensure that the width material does not break during assembly. When the depth of the notch is unbalanced between left and right, the part will be more difficult to break, leaving fibers and possible fracture edges.

The PCB in the array is scored

The more scribing is applied, the weaker the array panels may become, resulting in fragile handling, damaged arrays and/or assembly problems.

Parts with smaller ratings

The smaller the square inch of the board, the harder it is to disconnect. When the PCB size is small, boards thicker than 0.062 “are more difficult to separate. Less than 1 inch in either direction may require additional tools to separate parts.

Score the PCB which is too long

Printed circuit boards with a longer X or Y (12 inches or more) may be weak and easily broken if they are scratched too deeply. Adding heavy components to an already weak array can cause panels to break during handling, assembly, or even transportation. Implementing jump scores or tabular routing may be a better choice.

Scoring plate

If you are grading PCBS greater than 0.096 inches thick, use the same scheme, with the two blades cutting deeper into the laminate surface, leaving the net 0.020 inches +/- 0.004 inches. Above this thickness, it is difficult to break, because the bending is not enough. Thicker blades can use this method for thicker boards, but it can sometimes lead to problems with copper to edge spacing.

The scoring tool

There are tools available to assist in decanting PCBS. However, it must be used correctly and monitored for accuracy to prevent edge damage, breakage or surface scratching. Extra handling of fully assembled PCBS is always risky.

Add an Angle or radius to the part

Does this hinder the ability to use the scoring method?

No, but you still need flat edges to scratch the board. Normally, when using the notching method, the PCBS will dock with each other. The cutter cuts both the top and the bottom.

To mess with angles or radii, you must leave space between the PCBS. A typical Router planer uses a 0.096 “milling cutter that requires at least 0.100” to cleanly grind between parts. There is also minimal waste between parts. It is not recommended to use 0.100 “spacing and notching methods between boards, even with tools, it is too difficult to break. When space is required, it is recommended to use 0.200 “or greater spacing for nicks.

PCB design rules for designers

Answer a common question; Yes, you can grade almost any printed circuit board with a straight edge, but you may need to use a combination of scoring and wiring.

The high temperature laminated material with higher than 150TG has relatively dense material and microstructure. Do not use the standard fraction parameters used in the 130tg material standard. Deeper fractions are needed to easily break this stronger woven material. For higher temperature materials, use 0.015 “+/- 0.004” mesh.

From the edge metal, the protection layer should be customized to the thickness of the printed circuit board. When equal to or less than 0.062 “, the distance between the metal and the actual edge of the plate shall be at least 0.015 “. This is a good reference number. Thicker boards can be used 0.096 “or 0.125” up and 0.020 “or higher if space allows for all functions from the edge of the card.

For printed circuit boards less than 0.040 “in thickness, always plan to only use lugs for wiring to avoid any problems.