V-Score Board Separation: Why, How, and Thru-Hole Temporary Connection Trick
April 27, 2022
Blog
Some time ago, I wrote an article about panelization basics, mostly focusing on “mouse bites” as the panel separation technique. The other way to separate boards is using a technique called v-scoring. The basics of this technique are shown in the Royal Circuit Solutions video below, which is meant to selectively weaken a PCB for separation at a later point.
Generally speaking, panelization can allow a machine to put together multiple sub-board assemblies at one time. This also facilitates automated assembly of small boards that assembly machines couldn’t otherwise accommodate. In the case of a v-score, a board manufacturer partially slices through a PCB, typically 1/3 the total thickness of the board on either side, at an angle that comes to a point on the bottom. This makes it breakable by hand or even mechanically.
V-Score Advantages
- When separated, V-scores do not leave jagged edges that need to be cleaned up later in the same way that mouse bites do
- Setup may be simpler than mouse bites, potentially less costly
- Can have stronger board-to-board connections than mouse bites
- Very thin section of board area needed, typically less than 1mm
- Possible to make temporary connections as outlined below, temporary connections are also possible with mouse bites, but v-score may present advantages in a limited set of circumstances
V-Score Concerns
- Space must be left between components and edges to avoid damage during separation
- Significant force may be needed to break boards apart
- Restricted to straight lines, which generally go through the whole board, it’s also possible to do a jump-score where only certain portions are cut. This sort of jump-score technique appears to be much less common, and would require careful communication with manufacturer.
It’s important to note here that while V-scores are straight lines, individual boards can be routed on the inside or outside as well. Mouse bites would give you more freedom as to how the separation features are placed, but in combination with edge cut routing, may not represent a significant restriction. Either technique should work for the vast majority of board manufacturing scenarios, and at the end of the day, the decision may come down to familiarity and/or what the board house prefers.
Caption: V-score in combination with routed edges
Image Credit: Jeremy Cook
How To Add V-Scores to Your Board
As shown at ~3:24 in this video, adding V-Scores for panelization with PCBWay is quite simple using their EasyEDA tool, and can result in very reasonably priced boards. However, this operation appears to give little direct control over how its scored, which can be useful in some cases.
I haven’t personally used EasyEDA or JCLPCB, but have specified panelized boards from PCBWay. This procedure involved drawing the exact V-score lines on the KiCad User.Eco2 layer with notes indicating “V-SCORE HERE”. This was plotted and included with my other files, and there was a bit of back-and-forth communication to make sure everything was processed correctly. I also had to adjust my design to accommodate their minimum size requirements, which worked out to 60mm x 45mm.
PCBWay can also simply set up the panelization for you. Presumably, the same sort of customization could be done with JLCPCB and other manufacturers, though I have not experimented with this otherwise.
PCBWay’s V-Cut lines on a typical 1.6mm board is approximately .8mm in width. Since I copied and rotated the dual-board design onto the bottom to add space, I also inserted roughly .5mm of board material to help compensate for this material that would be lost.
Caption: My customized board setup: second set of boards rotated and pasted on the bottom longer footprint, with space left in between. Score marks in yellow
Image Credit: Jeremy Cook
Connect Over V-scores
For PCB manufacturing, through holes are drilled and plated before v-scoring is performed. If a V-score cuts through this hole half, the two sides are in fact still connected until fully separated, as only the outer third on each side is sliced.
Caption: Plated hole partially v-scored
Image Credit: Jeremy Cook
This means that it’s possible to have an active circuit before the v-score is separated, which is broken when the individual boards are de-panelized. The upside to this is that with careful consideration as to how this is done, it’s possible to program and/or test a number of boards at the same time, then break them apart for individual use. One can do a similar technique with mouse bites, using very thin traces between the holes.
For my particular board, I wanted it to serve one purpose when connected, then function as two separate parts when disconnected. Here, a single pin is shared between the two sides, so a header can be used across the 7 combined middle pins. The middle is normally not connected, but could be if needed. When broken apart, only the three holes on each side adjacent to the split hole will be used.
Another example of connected v-scoring is shown in the video below. This particular panel also uses mouse bites to complete the design.
V-Score Panelization: Another Tool in Your Kit
While v-scores aren’t needed for every PCB design, in some situations they present certain advantages. It’s good to have options. You never know when they might come in handy!
Jeremy Cook is a freelance tech journalist and engineering consultant with over 10 years of factory automation experience. An avid maker and experimenter, you can follow him on Twitter, or see his electromechanical exploits on the Jeremy Cook YouTube Channel!
