![]() Tip 2 - Creating Hole Tolerance Attributes for a Pad or Via Template In the Via Properties dialog, hole tolerance can be edited using Tolerance, in the top left-hand corner of the dialog (Figure 2).įigure 1: Hole tolerance can be specified in the Pad Properties dialogAlt Text: Hole tolerance can be specified in the Pad Properties dialog) ![]() In the Pad Properties dialog (Figure 1), hole tolerance can be edited under the Hole Information section. Right-click on the pad or via and select Properties. You can quickly set the pad/via tolerances using the properties of each. Tip 1 - Setting Hole Tolerance Attributes for Specific Pads and Vias In each method, you can set the minimum (-) and maximum (+) hole tolerance attributes. Hole tolerance in Altium Designer can be accessed and edited using several different methods, which we will examine below. Hole tolerances and defaults can also be established in the Pad Via Library panel and the Footprint Library. You can adjust hole tolerance attributes in the pad and via property dialogs. There is no default hole tolerance value in Altium Designer. A rule of thumb is that you should make a PCB hole 0.007 inches larger than the part lead hole diameter to accommodate all tolerance, drill wear or wobble, and plating variations. So, hole tolerance is critical in the design process to ensure proper placement of PTH parts. ![]() You also have to account for thermal expansion or shrinkage of the Printed Circuit Board PCB substrate as it is being processed. Mounting holes are then plated, and the plating may be thicker or thinner for each batch or position on the board. Or, the drill may vibrate or wiggle slightly in a hole, causing a slightly larger hole. Thus, 0.022+0.003+0.004 =0.029 inches, which is the smallest hole allowable on the board.Īs holes are drilled, drill bits wear and get smaller. So, the minimum hole size must accommodate the largest resistor lead plus tolerance (0.022 resistor lead + 0.003 resistor lead tolerance), plus the 0.004 PCB hole tolerance. The lead, whether at the large or small end of the tolerance band must always fit in the hole. Therefore, the leads on the actual part can vary from 0.019 to 0.025.Ĭommonly Printed Circuit Board PCB manufacturers specify a hole tolerance of ☐.004. For example, the datasheet for a specific manufacturer of 1/4-watt resistors specifies lead diameter as 0.022 ☐.003. TOLERANCESĬomponent datasheets list a tolerance with plus/minus to accommodate variations in aging, wear, temperature, plating, material, machining, and so forth. ![]() Here are five tips to help you with specifying pcb hole sizes tolerance. Now, Altium DesignerPCB design software allows you to add hole tolerance attributes for your pads and vias that will be communicated to the fabricator by inclusion in the drill table. ![]()
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