Author Archive: Kristina Chung

Techniques in PCB Assembly

If you are planning to do DIY PCB assembly, here are some techniques to help you out. Mainly, the success of your project will be dependent on following appropriate guidelines in CAD, lighting, cleanliness, and use of hand tools.

CAD considerations

PCBWhen it comes to PCB assembly, you will need to apply some alterations at the CAD level first so the succeeding techniques will also work.For one, if you plan to do the drilling manually or through your hands, the VIA pads must measure a diameter of at least 55mil to 60mil.

The SMT rectangular pads will then have to be longer. This way, they will be protruding out. This is necessary as well for the pads to be visible when your device is sitting on it. So when you are doing manual soldering, you will be able to observe and create a good quality and reliable joint.

Lighting

In terms of lighting, your best option is the 60W desk lamps. Use 2 of these and place one on each side of your work area. Make sure that you place the low to the bench in order to achieve maximum intensity. With that, you will have a well-lit work area. Plus, you will have no shadows to worry about.

Also a consideration in lighting is proper visual inspection. Find a good spot where you can set up and that will also go well with the light set up. Keep in mind that in PCB assembly, you will be relying heavily on your eyes. So the more illumination you have, the better you see, and the more efficient your work can become.

Cleanliness

In whatever project you are doing, keep in mind that cleanliness is very important. Keep your tools and work area clean. Tools and equipment must be placed properly in order to avoid accidents.

The pads must be cleaned using isopropyl alcohol and a soft toothbrush in order to get rid of the oxides. The latter can react adversely with your soldering. Also, an essential information to remember is that PCB will reoxidize within just an hour. Hence, you must do the cleaning right just before your soldering work.

Hand tools

If you do not plan to take soldering as a hobby, investing in the basic tools and equipment for your PCB assembly should suffice.One, the soldering iron. The modern temperature controlled version will do. Just make sure that the solder tip is pointed so that you will be able to reach even individual SMT joints. Plus, the pointed tips come with the added advantage of less capacity for heat.

Next, the tweezers. Do not ever use sharp tweezers because they can cause damage to delicate SMT resistors. On the other hand, the ones with flat ends are highly recommended.For the solder braid, go for the one with the narrowest grade. The fat versions will take longer time to heat up. This can, in turn, damage the pads.

Inspection eyeglasses

An X8 magnification will suffice for PCB assembly. Higher magnifications will not give you ample board area. You will also find inspection eyeglasses that come with a built-in measuring capability. This will serve you will in checking on the PCB pad as well as drill hole sizes.

Printed-circuit-boardsCut and crop tool

You may heard of this as the Cut and Clench tool, or the Cut and Crimp tool. Basically, they are all the same and for the same purpose. You will use this to squash the wire flat before making cuts above it.

Heat gun

This will come handy when you need to remove or rework SMT components. It comes in two forms—the paint strippers, and the hot air tools. The former is for removing bigger SMT devices or heating larger surfaces areas. On the other hand, the latter is for heating smaller areas and smaller SMT devices.

 

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