In designing a printed circuit board, the most important thing to consider is the functionality. This is important not only to serve functions but increase the performance in the long run. Here are some guidelines and important tips to consider in PCB assembly.
As a crucial process during the assembly, the design stage must be carefully considered. A large chunk of manufacturing costs can go to this process so it’s necessary that engineers must be able to decide on their preferred method in order to achieve both efficiency and productivity. It is necessary too that engineers know the total costs on the project design for adjustments when necessary.
It’s important to identify the common PCB assembly designs. In general, choosing an incorrect footprint is one of the most common mistakes because this can lead to smaller or larger specifications than what manufacturers require. Once neglected, this can result in more issues such as rework, delays in project completion and even performance issues.
A decrease in a manufacturer’s recommended spacing on the electrode can ensure a strong and stable connection. It’s recommended as well to design the boards to ensure that half of the leads are on the pads. Specifications used to control the quality of PCB are component placement, soldering including inspection.
Solder reduction can also pose as a common issue. One way to reduce this is to apply a reduction on the paste volume. This ensures a good connection on the solder. The recommended volume to use is at 20-50%. Adjustments on the window pane stencil pattern and the gutter size. Gutters can sometimes get blocked with the solder and can therefore cause some issues in the channel flow.
The assembly process includes some preparation on the board’s surface along with its components before these are used in the production. Although these processes are done using an automated system and machine, this can also be done at home with some modifications applied.
A PCB assembly also follows some spacing guidelines. For placement in a component to component scenario, a maximum spacing of 10 mils for smaller sized packages is important. This is already enough to accommodate any slippage that may occur during the solder process as there is a tendency for parts to drift when the solder paste is pressed.
For edge of board component placement, it’s necessary to place the components at around 125 mils from the edge of the board. As part of cost control, many parts are placed as near as possible to each other. As a result, this places too many components near the edge which can cause some issues.
Common mistakes happen as well when working with diodes and LED designation. Most of the designs submitted have missing cathode markers. During evaluation, lack of these components may place the project on hold and delay the production process.
Diodes and LED designation must have cathodes designated among them using a bar with a silk screen. This must still be visible even after it has been soldered. If you choose to have the polarity mark anode instead of using the cathode, this must be specified but in general, the bar should designate the negative rather than the positive. It’s important to place the numbers and components in pad on the way that these have been numbered by manufacturers.
Proper use of capacitors and polarity can reduce project delays. It’s important to designate the polarity on the capacitors depending on whether this is an SMT polarized capacitor or a Through-hole polarized one. SMT capacitors need to have their positive pads designated with a bar in the silk screen while through hole capacitors should have the positive sign silk screen that should be placed next to the positive pin of the pad when doing a PCB assembly.