Tab Routing (Tab Route PCB) because automated equipment for circuit board assembly frequently struggles to work with the smaller boards, assembly errors occur more frequently.
Several businesses employ a technique called panelization, which produces a Circuit board panel, to reduce these flaws and increase manufacturing process efficiency.
What Does Tab Routing Mean?
PCB panelization can also be known as tab route, as well as tab routing, and it involves arranging many boards of the same and various designs into a panel. This common technique for PCB panelizing makes use of tabs without or with holes.
During the tab route PCB construction process for panelized boards, single boards can be detached by severing or cutting those tabs which are located between the boards or between its array rails and boards.
Several circuit boards can be fabricated and assembled in one go using a panelized Circuit board array with tab-routing. As a consequence, the project’s expenses are reduced, and the Circuit board order is completed more quickly. Choose the perforated kind if you want to manually separate the panelized Boards. Use a specific depaneling tool, such as depaneling carriers to avoid board damage when you believe that removing the PCB from this assembly array will put an undue amount of stress on a tab route PCB.
The ability to create non-rectangular boards is one benefit. Tab-routing, on the other hand, has the drawback of using more board material that might raise your prices. The board around the tab may also be put under extra strain as a result. Avoid putting PCB components extremely close to the tabs to reduce board tensions. Although there isn’t a set distance for positioning parts close to tabs, speaking generally, 100 mils seems to be the recommended distance. With larger or thicker Circuit boards, you might also need to space components apart by upwards of 100 mils.
Circuit boards in panels could be taken out either after or before assembly. The most popular method is to disconnect the PCBs once the panel gets put together since the PCB panels usually make assembly simpler.
Tab Routing Design Considerations
In situations whereby components are situated extremely close to as well as over the edge, tab routing is typically recommended. It is also preferred for PCBs with non-rectangular geometry, such as circles. To guarantee the strength as well as operation of such arrays, particularly during this breakout process, numerous design decisions must be taken since the tabs serve as the arrays’ breaking points. These factors include, among others:
Clearance
Keep traces and parts at minimum 1/8 inches from the tabs due to the tension put on its breakaway points as well as the risk for splintering.
To guarantee minimum interference, the surface-mounted ceramic multilayer chip capacitors should be maintained farther away, a minimum of 14 inches from its tabs.
Knock-Outs
To avoid problems during the wave-soldering process, the placeholder, also known as a knockout, could be necessary if the PCB design has holes that exceed 0.6 inches. Knockouts are especially crucial in the centre of the array, when PCB arrays become more inclined to droop. While bigger, more atypically shaped knockouts might need numerous three-hole tabs that are perforated, rectangular and smaller knockouts may include a broad, perforated tab (5 hole) on one edge.
Tab Positioning
Maintaining the PCB array design’s integrity is crucial. Perforated tabs (Five-hole) must be spaced per 2-3 inches across the edge of a board, as well as perforated tabs (three-hole) must be spaced each 1.5 inches. To prevent a board’s edge from curving, tabs must be positioned as near to it as feasible. Nevertheless, tabs shouldn’t be put under any overhanging components. Your designer should also make sure these tabs are adequate for supporting the boards without obstructing the breakout procedure.
Placement of Perforations
If you wish to prevent protrusions from your board’s sides, never run tab perforations along a tab’s center; rather, run them near the PCB’s edge, or on every side of that tab if positioned between two printed circuit boards.
Array Arrangement
To ensure uniform break-lines across the array, place PCBs such that all tabs that are broken at once are collinear. If break-lines here are not consistent, certain tabs could break whereas others are merely pushed perpendicular to such board surface that will damage the lamination.
Your design must meet few problems throughout the manufacturing as well as breakout processes if these factors are taken into account.
V-Score vs. Tab Routing
Whatever PCB design you’re dealing with will play a significant role in your decision to employ tab routing or v-score methods in the PCB panel. Before deciding, take these things into account:
Board Shapes: The panelization process heavily depends on the PCB’s shapes that make up an array. For rectangles or square board types, the V-scoring will work well.
When dealing with odd forms, tab routing seems to be more suited.
Edge Components: Tab-routing or a version of it may be preferable to V-scoring if your PCB needs the availability of the edge-hanging components as well as components positioned close to the edge. Just make sure the tabs aren’t close to such edge components.
Edge Quality: Tab-routing might well be preferred than V-scoring if the edge quality is a consideration. Despite the fact that the method leaves behind a few tiny, rough laminate nubs, these may be readily removed with sandpaper, and the rest edges remain smooth due to the routing. On the contrary side, V-scoring produces rough edges around, which might also need additional sanding if clean edges are required.
Time Expense: Since tab routing needs a great deal of time upon that router, it often requires more effort and time to set up. On the contrary, V-scoring, takes substantially less time on the computers.
Waste: V-scoring provides the most advantage when material waste seems to be an issue. The process wastes a lot less material compared to tab-routing, which results in a lower cost for every board overall.
Defaults for Tab Routing
If there are no panelization remarks from customers, our CAM experts will put up the panelized tab-routed array using the specifications shown below. Verify the specifics of our journey and keep panelization.
- Position the tabs so that they are at a minimum of 9 mm from each board corner.
- Place tabs on center or at minimum 9mm away from datum holes.
- Use the 2mm router. Boards must be spaced apart by at least 2mm.
- Where feasible, make sure these tabs are positioned in one straight line having an X-Y axis.
- Don’t tab the traces or part holes that are close to the edge of the board. This is to prevent breaking traces or holes.
- The tab’s width is between 3mm +/- 0.25mm.
- The tab position tolerance has a dimension of +/-0.5mm.
- On the 0.5mm grid, tabs must be dimensioned into the center.
- Place tabs on the outer edge of the board at minimum +/-6mm from every radius.
PCB Panelization Benefits
PCB panelization has advantages beyond only making smaller circuit boards fit into common production procedures; it also improves production efficiency. Additional benefits of Circuit board panelization are discussed below:
The ideal method for producing circuit boards in large quantities is PCB panelization, which saves time and money.
Handling a huge sheet as a collection of smaller boards is a quicker and more effective approach. The cost-effectiveness of employing the standard size of the fabricator for the boards allows for the fabrication of more boards in a shorter amount of time.
Furthermore, PCB panelization gives designers a way to incorporate distinctive designs in prototypes that are more affordable and effective.
Circuit boards are shielded from shocks as well as vibrations. These come from the occasionally harsh environment of a production line via PCB panelization. Hence, via manufacture, it ensures the security of the boards.
PCB Boards Breakout Instructions
Even with excellent PCB array design, issues can still arise when handling the breakout. A board can be completely destroyed by the breakout if done incorrectly, resulting in component damage, splintering, and ripping. Because of this, using effective board breakout techniques is crucial to minimizing expenses. To prevent any such problems, keep these rules in mind as you work through the process of breakout:
Hand Tab Breaking: With the right hand tools, a correctly constructed tab routed Circuit board panel is frequently breakable. Employ wide-nose pliers for bending every tab inside a break-line. This is done till it loudly fractures for the greatest results when using hand tools. Bend these tabs into the other direction so that they fully split along its break-line.
Breaking Tabs with Machine: The board might occasionally become too thick enough to completely break by hand. It could be preferable in this situation to use a cutting instrument. As was the case with solid tab type of panelization, a depaneling router could be a wise choice.
Cutting V-Grooves: A certain kind of a depaneling machine is needed to release panels with V-Scores. This machine employs a pizza-cutter-style blade, which is reasonably priced and needs no upkeep. The edges are going to be somewhat harsher than choices with routes, but that is the only downside.
Conclusion
In situations whereby components are situated extremely close to as well as over the edge, tab routing is typically recommended. It is also preferred for PCBs with non-rectangular geometry, such as circles.
