The 5 Heavyweights in PCB Panel Design

PCB Manufacturing

PCB panelization is an essential part of PCB design. For this reason, designers need to consider its potential impact on the PCB assembly process and the PCB itself.

PCB panelization is when smaller boards are placed in a connected array (panel) to make it easier to fabricate and assemble PCBs.

PCB panelization and PCB routing
The correct panelization of PCBs can decrease PCB manufacturing and assembly costs and positively impact PCB quality, reliability, and aesthetics.

So, what’s the best way to approach the design of your PCB panels and what are the basic determinants in this process?

  1. Panel size – panels can be built to different sizes; the standard size is 18 inches by 24 inches for many panels.
  2. PCB shape – Your board’s shape can complicate panelization. Although rectangles are ideal, alternating your images from 90° to 180° can help you maximize the area of your board if the shape is complex. To fit unusually shaped boards into an array, use a CAD program.
  3. PCB Singulation – clearances are required to avoid damage to the components and circuitry when depanelizing. Remember, every notch placed in the PCB panel to facilitate PCB breakout will weaken the panel somewhat.
  4. Component clearances from PCB edges – components and circuitry need to be a safe distance away from the PCB edges to protect them during depanelization.
  5. Component alignment – important if the PCB will be going through wave soldering.

One of the critical elements of PCB panelization is the breakout. Whenever a cut is made in the array to facilitate future PCB breakout, the panel is weakened.
Following some guidelines can help you avoid problems during PCB assembly.

 

PCB Panelization Types

1. V-groove (V-scoring) Panelization

V-grooves are made in a PCB by using a drill or triangular saw to cut away the top and bottom sides of the board. It is important to pull back the copper from the board’s edge so the copper is not exposed when the boards are v-grooved.
V-groove PCB panel

This method is ideal for square boards or when there are no components overhanging the edge of the PCB, and is suitable when cutting a straight line through the PCB array. This approach will prevent thin boards from bending during the SMT pick & place process.
However, the v-groove method does not result in very smooth or clean break-away edges.

2. Tab-Routing or Breakout Tabs

Breakout tabs are made using a router to mill around the panel outlines, except for strategically placed tabs that are broken away for depanelization. In cases where the boards have complex shapes or components, such as connectors that overhang from the board, breakout tabs provide more flexibility.
Tab routed PCB panel

Typically, each tab has three to five holes drilled into it, which have a 0.020-inch diameter are spaced 0.030 inches apart. These tabs make depanelizing boards easier and result in smooth, clean edges with no burrs.

In Sum

PCB panelization is a critical consideration that no designer can ignore. Designs for PCB arrays can significantly impact, either positively or negatively, the PCB assembly process. It is essential to keep in mind the various considerations, including PCB shape & size and component clearances, as well as other factors. Array design can also significantly PCB cost, auesthetics.