Screaming Circuits: Where to Put Panel Tabs

PROTOTYPE AND SMALL VOLUME
PCB ASSEMBLY MADE EASY

Where to Put Panel Tabs

Many small quantity PC boards are ordered individually cut. They come to us as a set of unconnected boards. For small quantities of reasonable size boards, it makes the most sense to order them this way. However, for really small boards, and larger quantities (50 or more), purchasing boards in a panel (also called an array) is more appropriate. It reduces errors and assembly time.

There are a few additional factors to consider with panelized boards.

  • First of all, don't try and create a panel in your CAD software. Just lay it out as a single board and have the FAB house put it in a panel. You'll get the most efficient use of PCB space that way, and the FAB house will create the files in the format that the assembly shop (Screaming Circuits) needs.
  • Avoid family panels. A family panel is when several different boards are put onto the same panel. The boards in family panels often repeat reference designators, which causes problems at assembly. See this blog article on how to properly assign reference designators on a family panel.
  • If you have overhanging parts, like the increasingly common micro USB connector, make sure that the panel tabs aren't placed near the over hanging parts.

This blog article here, gives some background on the connectors.

If you have overhanging components, make sure that the panel tabs are not placed where the over hanging components are. Some components, such as the connector in the link above, have protrusions that will keep it from laying flat on a panel tab. In all cases, even without the protrusions, the operation of separating the panels with a component on the tab can weaken the component solder joints, or even pop it off the board completely.

How not to do it:

Overhanging connector On tab 800

Instead, make sure that the tabs don't end up under your overhanging component. Have the tab moved like this:

Overhanging connector Off tab 800

You can put this instruction in the Document layer of your CAD file, or in a separate document covering fab instructions. In the CAD image below, the overhanging component has a Keepout area. The Document layer has instructions to keep panel tabs out of the area.

Overhaning part keepout

If in doubt, don't hesitate to contact us or Sunstone Circuits directly to ensure that your instructions are clearly communicated.

Duane Benson
Wood paneling as a wall covering is really out of style

 

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