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Bridges and Frames

When milling the contours of your PCB at the end of the fabrication process, it is necessary to hold it place. That's why we define small areas (bridges) at defined points around your PCB, where no material will be removed by the milling tool. Moreover, we add a frame around your PCB in certain cases. Here again we set bridges between PCB and frame to achieve the required stability during the milling process. Small drills inside the bridges allow you to separate PCB and frame easily from each other.

About this article

This article provides you with further information when we set a frame and how we set bridges. If necessary, it will help you to adapt your PCB design (e.g. when integrating Castellated Holes)

Framed PCBs

There are three cases when you can expect a frame around your PCB:

Small PCBs

Every PCB which fulfills the condition (height + width) < 60 mm (2.36 in) is classified as a Small PCB. Due to their small size, it is sufficient to set a bridge in the middle of the left and right edge to connect it to the surrounding frame. As most of the PCBs including Castellated Holes fall under this category, there is no need to worry about bridges which might affect the functionality of your Castellated Holes in this case. Just make sure, that you place the Castellated Holes on the top and / or bottom edge.

Frame thickness: 2.6 mm (0.1 in)

AISLER - Small PCB specifications

Non-rectangular PCBs

If your PCB is not a Small PCB and it's shape deviates strongly from a simple rectangular form, we add a rectangular frame around it. In this case, we place additional bridges on the top and bottom edge. In addition, the amount of bridges increases with the outer dimensions (bounding box) of your PCB. Read more about this in the following section.

Frame thickness: 2.6 mm (0.1 in)

AISLER - Non-rectangular PCB specifications

When selecting the Rapid Registration Add-On

When the Rapid Registration Add-On is the selected, a frame with two 3 mm (0.12 in) mounting holes will be added automatically to your PCB. The amount of bridges between PCB and frame, as well as their distribution, always follows the same rules:

Bridges are evenly distributed on the board outline of the PCB by using a raster (see pictures). The number of bridges and their distance from each other is in each case (horizontal, vertical) equal - so you won't find two bridges on the left and just one on the right side. In case of a non-rectangular PCB, we project the position of each bridge from a bounding box onto the board outline.

Frame thickness: 5.6 mm (0.22 in)

AISLER - Rapid_Registration Add-On Frame specifications

Reminding Bridges when including Castellated Holes

Bridges can effect the functionality of your Castellated Holes, if their positions are overlapping. The easiest way to prevent this is by designing your PCB as a Small PCB and placing the Castellated Holes on the top and / or bottom edge. If your PCB exceeds the maximum dimensions of a Small PCB, we recommend you to select the Rapid Registration Add-On. In this case, bridges will be set deterministically following the rules mentioned above, so you are able to adapt your design and/ or the position of the Castellated Holes. The length of a bridge is about 2.6 mm (0.1 in).