SMT or THM? This is the question most opinionated electronics buffs want to answer. Through-hole mounting, or THM, is old technology, but is still the king for many enthusiasts. Surface-mount technology, or SMT, is the latest technology but is too sophisticated and its tools are too expensive. Both, however, must be thoroughly understood before any judgment is passed. These technologies affect the way how an electronics technologist treats printed circuit boards. These can also affect how a consumer electronics investor predicts his return-on-investment. This can also affect how an investor, who engages in consumer electronics, sees his return-on-investment.
In this article, you will understand the difference between the traditional THM and the highly advanced SMT. These technologies are both used in attaching components on printed circuit boards via various soldering techniques.
Surface Mount Technology (SMT)
Surface-mount technology is used in most modern electronics devices like mobile phones, computers and other digital appliances. It is actually a method where components are just mounted onto the surface of printed circuit boards. The components and boards are then baked in an oven for them to bond permanently. An SMT device, or SMD, offers these advantages:
• Components are smaller than their THM counterpart
• More components are packed per unit area, therefore more connections can be placed in a smaller area
• Most SMT components are less expensive than their THM counterpart
• Lesser holes are to be drilled, which can save you more time and money
• No holes can also mean that one side of the board cannot physically, or electrically, affect the other side of the board
• Aggressive shaking and continuous vibration do not affect the performance of the circuit
• Assembly-line friendly, saving you more time, money and even personnel resources
• Tasks can be programmed, thus, resulting to repeatable and reliable output results
As you can see, SMTs do have various benefits to an assembly line type of electronic products business. This technology, however, also has its share of flaws.
• Sophisticated tools and large amount of money are needed to use this technology
• Prototypes are hard to develop, especially if you rely on breadboards and universal protoboards
• Broken circuits are difficult to troubleshoot and repair, as well
• More prone to mechanical, electrical and thermal damages
• Direct impacts may permanently damage not just the solder joints but the board, as well
The reason why SMT circuits are difficult to develop, troubleshoot and repair is because of the size to the components and their pins. The pins are so small that they cannot fit into a breadboard. The components are also too tiny that it requires a magnifying glass and a lot of patience just to insert a test probe into one of their pins.
Through Hole Mounting (THM)
Through-hole mounting is widely used for prototyping and creating electronics kits. It is popular among small businesses, researchers, and electronic enthusiasts. It requires printed circuit boards to be drilled. Electronics component are then mounted to the resulting hole. THM is still necessary for thermal, electrical and mechanical devices. These are some of the advantages of selecting this technology:
• Easier to acquire, learn and adjust
• Simpler tools and equipment to start with
• All components of THM follows the standards in manufacturing
• Tester-friendly, because of the large components and pin gaps between components
• Components are tough against electrical and thermal damages.
• THM has stronger mechanical bonds
This technology does have many weaknesses though, such as:
• Relies on drilled holes
• Drilling holes are time-consuming, thus can give you additional manufacturing costs
• Inappropriately drilled holes may also render the whole board useless
• Not assembly-line friendly, it relies on skilled workers to complete various, and perfectly-soldered printed circuit boards
• The non-repeatable output due to the different worker’s soldering levels can also create different output products
There are different pros and cons for every technology that you will use. THM is used more by small businesses down to electronics hobbyists. It easy to learn and the equipment are easy to acquire. SMT, on the other hand, is used by large businesses because of its benefits when incorporated in an assembly line. Both have their advantages. Most large and smart electronics businesses use both.