Printed circuit boards work as functional cells of any electrical, electronic, or electromechanical device or system. Each of these PCBs have several components mounted on them. There are wires, vias, and so on for which holes are drilled on the board in the designated areas. It is crucial that the components and wires fall in the right slots, and hence drilling holes is an extremely important process which needs to be performed by following standard guidelines. This process comprises drilling holes, slots, and cavities into the board. The holes drilled are of various types such as thru holes, buried holes, micro holes, and so on.
Important Pointers to Know Before the PCB Drilling Process
As mentioned, this process is crucial, time consuming, and costs high. It’s extremely intricate and has zero tolerance for any error because once a hole is drilled it cannot be reversed. So, it is crucial to have enough expertise and the right equipment. Here are some important pointers which serve as a guide to the PCB drilling process.
- Before beginning the actual process, one needs to know the type of holes, equipment used, board design vis-à-vis the drill diameter, and more.
- The drilling equipment may comprise either mechanical or automated drills. There’s laser drilling equipment too. This is done in large volumes at a time with the help of CNC machines.
- There are plated and non-plated thru-holes. Most of these holes are for mounting components.
- Mounted thru-holes are a type of non-plated thru-holes used where the vertical alignment of a component is not that crucial.
- For components that need to be upright vertical, fasteners are used for additional support. These are also a type of non-plated thru-hole.
- There are some components which generate heat, which needs to dissipate to prevent overheating or shorting. Such components when mounted have a bolt head beneath that can be lowered. Such surfaces are drilled with countersink holes which allow the lowering movement of the bolt head.
- Plated holes comprise various types of vias and press-fit. Among these press-fits offer perfect fitment and hence do not require soldering.
- Thru-hole vias are used for routing traces from top to bottom as well as routing signals between layers by acting as conductors.
- Micro vias are used for routing high-density signals, and may be either blind or buried.
- Buried vias have connections buried between inner layers of the board, which do not extend beyond the defined board surfaces.
- The layer stack-up of the board is defined in terms of extending the electrical connections. Blind vias electrically connect these defined layers which may be lined from the surface layer to a specific internal layer.
- Thermal vias are used when there are powerful components on the board. They are essential to release excess heat.
- Most of these vias can be created using either mechanical or automated equipment. Micro vias require laser equipment.
- As a standard, it is best to follow and implement DFM for the drilling process, and in fact for the overall design and manufacturing of PCBs.
- PCB shapes and sizes may vary with each application. The CNC milling machines must be such that they can cater to any of these non-standard requirements.
- The standard diameter of the drill must be set by design engineers. In most cases, drill diameter may be of the same size with slight variation. Here, it is crucial to set the correct drill size. Very small sized drills such as microvias are challenging and need laser.
- Before actually beginning the drilling process, drill a pilot hole and inspect it to avoid further errors and costs.
- Along with the size, the amount of power consumed and speed of operation must also be set.
- Once a hole is drilled, clean the board as it may have particles and dust.
- After drilling, soldering may be required in some cases.
While this guide to the PCB drilling process may be useful, you may want to consult a PCB manufacturer and assembler. If you are an OEM of electrical or electromechanical products, you may need to partner with a reliable PCB manufacturer and assembly services provider. Ensure they are experienced and understand your requirements well. Also, ensure they have expertise in making PCBAs for your product segment and offer customization as well. Rigiflex offers customized and end-to-end PCBA solutions. The company follows industry standards for manufacturing, assembling, and testing, and opts for automated PCB drilling process to ensure accuracy.