Printed Circuit Boards (PCB) has exceeded a $60 billion market. Growing at a rate of 1.7% real growth or more since 2011, printed circuit boards are now used in all but the most rudimentary electronics products.
Here’s what you need to know about the design and manufacturing process of printed circuit boards before manufacturing your first printed circuit board prototype.
The designing of a printed circuit board prototype
Your printed circuit board prototype will be designed for its specific use. It’s size will depend on the size of the space you plan to place it in. When designing printed circuit board prototypes, designers will use computerized design software which can help them lay out how the circuits will fit on the PCB. The designer will also use this software to determine the location of the holes for the contact points or component leads. Today, PCB’s are amazingly small, with the spaces between electrical paths not exceeding 0.04 inches (or 1 millimeter), making the design process one of incredible precision.
The assembly of a printed circuit board prototype
Your printed circuit board prototype can be constructed in one of three ways: as a single-sided PCB, double-sided PCB, or multi-layered PCB. You’ll have the highest component density capacity with a multi-layer prototype PCB, where multiple layers have been laminated together. The conductors on each layer will be connected with vias.
In prototype PCB manufacturing, a via is made of two pads that connect corresponding positions on different layers of the printed circuit board prototype. There are two methods of connecting these components: with “through hole technology” or “surface mount technology.”
Through hole technology is the older means of connecting components, used in the first printed circuit board prototyping. Components are electronically connected by leads which are inserted through a hole on one side of the board. The leads are then soldered onto copper traces on the opposite side of the PCB. This method of assembling prototype circuit boards replaced earlier techniques and was used from the second generation of computers until surface mount technology replaced it in near the end of the 1980s.
Through hole manufacturing is more costly because it requires holes to be drilled very precisely and restricts the area available for routing single traces on multi-layer PCBs. Since the inception of surface mount technology, through hole mounting is only used for components that are too large to be mounted with the surface mount method.
In surface mount technology, the components themselves are designed for mounting with small metal tabs or end caps built into their design. These tabs or caps could then be soldered directly to the PCB’s surface. This removed the need for wire leads and holes to be drilled in the PCB. At the same time, components also became smaller and it became more popular for them to be placed on both sides of the printed circuit board prototype. This enabled the assembly of smaller printed circuit board prototypes with far higher densities. Components can range from one-quarter to one-tenth of those of through hole components.
Surface mount technology is also a highly automated process, making it low-cost for its low labor requirement. It’s also more suitable for high production rates than through hole manufacturing. For high production, the most suitable method of attaching components is likely surface mount technology with bulk wave soldering or reflow ovens. That being said, there are many skilled technicians who can solder incredibly tiny parts by hand. For example, a technician could solder 0201 packages, which are as small as .02 inches by .01 inches.
Protecting and packaging your printed circuit board prototype
If your printed circuit board prototype will be intended for extreme environments, you’ll likely want to include a conformal coating. A conformal coating is applied after the components have been soldered by dipping the printed circuit board prototype or spraying it with the solution. In some instances, plastic can be sputtered onto the printed circuit board prototype in a vacuum chamber, though this is less common.
Earliest conformal coatings used wax as a sealant to prevent corrosion and leaking currents, but more modern materials are solutions of silicone rubber, polyurethane, epoxy, or acrylic.