subject: Printed Circuit Boards Surface Mount Technology (smt) Tips [print this page] Many people dont like to deal with surface mount technology (SMT) because of some misinformation about it. There exist several good references for commercial assembly, but not much is written about prototyping and hand soldering with SMT.
SMT is a type of electronic component package. Surface Mount (SM) is one of two categories of electronic components; the second is through hole (TH). SM components are designed for loading and soldering on a specific side of the printed circuit board. TH is designed for loading and printing on one side of the circuit board.
Why is SMT used in industry?
SMT offers several important benefits over though TH -- including smaller physical size with the same electrical function -- are cheaper in terms of raw material, have less unwanted effects and are faster for automatic machines to place. The greatest advantage of SMT is the real estate saved by not drilling holes through the board. That allows the board to have more trace and thus be more compact in size.
Why should you care about Surface Mount Technology?
SMT increasingly affects those involved in development, repair, and modification of electronics. SMT equivalents are quickly replacing the TH components as producers increase their investment in SMT production equipment to reap the benefits.
SMT Myths
Some of these myths include the idea that SMT requires special training, professional PCBs, special expensive equipment, and other components that are difficult to find. Most printed circuit board assembly houses do not have any problems with SMT. Find out before you place an order. Sierra Circuits in Sunnyvale, California has an amazing assembly facility with years and years of experience. They can handle SMT, TH, BGAs or any other technology.
Tip to Use SMT without Stress
To use SMT without stress, you must practice your technique, keep a steady hand, have good eyesight or use some sort of magnification, and use a good pair of tweezers.
How can SMT help you?
SMT offers many benefits over leaded components. These include:
SMT resistors are simple to parallel together and quick to solder and de-solder. Not working on both sides of the board at the same time reduces frustration.
When using RF signals, unwanted effects in SMT parts are fewer than parts.
When space is limited, SMT parts fit perfectly on the gaps of VERO board and posses the ability to mix with designs that utilize leaded parts.
When hole drilling is an issue, SMT streamlines this because you load and solder on the same side.
Tips for soldering SMT Parts
Good soldering techniques come with practice. There are also a few tips to follow, including keeping the circuit board clean, using the correct soldering iron for the job, selecting the correct tip and using solder flux where possible. For practicing, use SMT resistors because they are not easily damaged.
What parts can you recycle?
Its possible to obtain many SMT parts from surplus or junk equipment. It saves money and allows or good de-soldering practice. Ceramic capacitors are problematic as they crack easily. Resistors, inductors and transistors can be verified for proper operation, but excessive heat may damage the device. For a list of all parts, there a couple good component suppliers. DigiKey is one of the more popular ones. You can also scavenge old computers, cell phones, TVs, etc.
Amit Bahl
Director of Marketing and Sales for Sierra Circuits, Inc.
Amit is tasked with exploring and developing new markets for High Density Interconnect PCBs and Microelectronic substrates. Sierra Circuits, Inc. has primarily serviced the quick turn prototype market and is now actively developing the Medical, Military and Automotive markets. Prior to joining Sierra Circuits, Inc., Amit Bahl was a part of IBMs Global Services team, where he worked on automating and optimizing business processes using the latest Information technologies. Amit Bahl received his B.S.C in computer science with a minor in marketing from UCLA.
