The Importance of V-Scoring in PCBs
Rush PCB recommends using V-scoring in Printed Circuit Boards (PCBs) for easily removing individual boards from a circuit board array. V-scoring a board array requires a precision scoring tool with a pair of top and bottom cutting blades. The PCB manufacturer either runs the cutting blades across the panel in a straight line or pulls the panel through the blades to create the scoring.
For separating parts from a completed PCB assembly panel, Rush PCB offers V-scoring as a great cost saving and a highly efficient way. Our customers consider our offer of V-scored PCBs as a great value add.
V-Scoring and Jump-Scoring
Very often designers and manufacturers place a set of smaller boards together in an array to make the assembly process more efficient. After assembly is over, the assembler manually separates the individual boards from the array. To make it easier for separating the boards without damage, the manufacturer scores a v-shaped breaking line along the intersection between individual boards using a precision cutting tool. The idea behind scoring the PCB is to provide a solid structure for the board assembly, while allowing for application of minimal pressure to separate the assembled boards. Rush PCB follows some rules for V-scoring PCBs:
- Only straight scoring lines
- Vertical and horizontal scoring lines allowed
- Scoring lines from one outer edge to other outer edge, except in jump-scoring
- Scoring recommended only above minimum PCB thickness of 1 mm
- For PCB thicknesses 0.8 to 1.0 mm, one-sided scoring possible
During V-scoring, the manufacturer cuts a v-shaped groove on the top and the bottom sides of a circuit board, while leaving a small amount of material in place to make the PC boards stay in place. The general practice is to cut the grooves to a depth of 1/3rd the board thickness on the top and bottom, leaving a thickness of 1/3rd in the middle.
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For thin laminates or when the board has heavy components, scoring lines from one outer edge to the other may be problematic during assembly. In such cases, unscored waste rails are necessary to maintain the strength of the array to prevent the individual parts from falling apart before the assembly is over. Manufacturers get over this problem by lifting the scoring blades off the PCB surface before they get to the end of the panel. As the blades need to jump over some parts of the PCB, manufacturers call this process jump-scoring.
Rush PCB has the state-of-the-art V-scoring equipment for creating PCBs with V- and jump-scoring. Contact us for your requirements.
V-Scoring Equipment
At Rush PCB, we have the latest V-scoring equipment with programmable blades. We can program the blades to lift off the panels at the appropriate location. We have experienced personnel who know how to jump-score properly, as errors in jump-scoring can affect the quality of assembled PCBs.
Timing the jump-scoring is important, as allowing the blades to cut into the waste rails could weaken the panels leading to problems of separation before assembly. On the other hand, if the blades jump too early, it can reduce the V-scoring depth, and the assembler will find it more difficult when separating individual boards from the array.
V-Scoring Requirements
Designers must be careful with V- and jump-scoring to indicate accurately and define the parameters on the design drawing. The positional and alignment accuracy of the top and bottom grooves is critical for a clean separation and to minimize the post-separation smoothing for the board edges.
IPC-2222 Section 5.3.1 defines the alignment tolerance for V-scoring to ±80 µm. It is possible to have 90-degree groove or a 30-degree one. Whatever the angle, the designer must maintain a track routing distance of at least 1 mm from the scoring edge top, to prevent damage during de-paneling. Rush PCB recommends that the designer and the fabricating shop collaborate on the V-scoring angle options available.
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Disadvantages of V-Scoring
- Difficulty in breaking individual parts from the array
- Poor scoring due to dull blades
- Not suitable for low-tolerance PCBs
If the two grooves on the PCB are not deep enough or do not align properly, the assembler may have difficulty in breaking individual parts from the array. This may cause the forces placed on the assembly to create a haloing along the parting edge. This may result in fracturing the PCB laminate such that the separation happens outside the v-scoring channel, resulting in uneven breaks along the board edge.
Dull cutting blades of the v-scoring equipment may result in offset v-score, or excess material between two board sections. This causes uneven and difficult separation of individual boards.
Although the excess material remaining along the edges of boards separated by v-scoring is too minute to affect in fitting, boards with very low tolerance for unit fit may face an issue.
Contact Rush PCB for all your PCB needs, including V-scored PCBs. Call us or visit our website today.