You might have asked yourself, who SMT manufacturers are, what SMT is even all about. Now, check into any electronic equipment made commercially, you will discover that minute devices fill it up. Instead of making use of traditional components using wire leads, the mounting of these components are done on the board’s surface with many of them having minute sizes.
This technology used by SMT manufacturers is called SMT, Surface Mount Technology. Virtually, all the equipment of today that are produced commercially makes use of surface mount technology. This is because it delivers great benefits during the smt electronics manufacturing of printed circuit boards. Also, due to the size of these SMT components ensures that more electronics can be packed into smaller spaces.
Asides the size, this technology allows SMT manufacturers to perform automated assembly of the printed circuit board. It also allows soldering, and this ensures that there is great improvement in functionality and reliability, and will save some cost.
How do SMT Manufacturers Work?
SMT, which in full means surface mount technology, is a very new way used by smt manufacturers to get components arranged on a printed circuit board. Years back, engineers and electricians would utilize leads in order to get components of circuit boards fitted through holes.
Preparing carefully was very necessary to make sure that all the leads were rightly formed to fit the different board types. SMT assembly has become a more efficient and better process that ensures the direct soldering of components to the board.
By getting rid of having to pass the leads via PCBs, this process has become more cost-effective, efficient, and faster. Also, SMT assembly is beneficial to the smt manufacturer because it helps in saving space, thereby allowing the housing of more components on a much smaller board. From this, we can now see clearly why there are lots of smaller modern devices but have lots of great features packed into them.
The SMT process is a very intricate one. Here, each of the components is positioned strategically and then mounted properly on electrical boards to ensure the best performance. This is one good reason why both the SMD and the SMT overlap. To have an efficient electrical device, there’s a need to combine the right mounting strategies and component selection.
With SMT, smt manufacturers have an opportunity for automation. The programming of machines to mount some components on the printed circuit board directly within a very short time is possible. What this means is that production comes faster, there is higher quality and there will be a significant reduction in risks.
What does SMD Mean?
SMDs also referred to as surface mounted devices are components attached to PCBs. In our world today, there’s a great need for a more cost-effective, more flexible, and faster components. This is why SMDs have significantly evolved.
SMDs now make use of pins, which can be soldered onto the pcb directly instead of making use of leads and the wiring via a circuit board. There are numerous benefits of making use of pins over leads. For instance, you can achieve this same function using smaller components. What this means is that more components could be used in fitting into smaller circuit boards. In addition, it is possible to enjoy increased functionality.
Due to the fact that no hole is needed to drill into the board, its process of mounting becomes more cost-effective and faster.
The best way of having an effective device is by choosing the best and right SMD. It’s advisable that you consider what fits best into a printed circuit board. Also consider the mounting arrangement or strategy that will suit your device. The existence of SMD has been for a long time, traced back to when soldering was done by hand. Today, SMDs like ICs, resistors, and other components can be mounted automatically on the PCB’s surface. By making use of the right process for arrangement, SMDs could perform at very productive levels for longer periods.
Different packages exist for different component types. These package styles can be categorized into three. These are integrated circuits, diodes and transistors, and passive components. Let’s discuss these three categories broadly.
Types of SMT Components
As mentioned earlier, there are three major types
Passive SMDs
Here, there are different packages for the passive SMDs. Most passive SMDs can be either SMT capacitors or SMT resistors. Also, the sizes of the packages are well standardized. Components like crystals, oils, etc, usually have more requirements and therefore have their personal packages.
Capacitors and resistors usually have different package sizes. Their designations include 1206, 1812, 0201, 0402, 0603, and 0805. These are not used widely today, because smaller components are now generally required. But, they can be useful in applications requiring larger levels of power, as well as areas where larger sizes are required.
Diodes and transistors
SMT diodes and SMT transistors are usually kept in a small package made of plastic. Connections here are made through leads. These leads come from the package, and they are usually bent. This is so to ensure that it comes in contact with the board. There are three leads for this package. By so doing, it will be easy to tell which of the ways the device should go.
Integrated Circuits
Different packages work with integrated circuits (IC). The type of package to choose will depend on the interconnectivity level required. Majority of chips may need just 14 or maybe 16 pins. Others, such as the VLSI processors and other chips associated, can need about 200 or more.
Due to the different requirements, there are other packages available. Smaller chips require packages like the Small Outline Integrated Circuit (SOIC). In addition, smaller versions are available like the Shrink Small Outline Package (SSOP) and the Thin Small Outline Package (TSOP).
For VLSI chips, a different approach is required. Here, a quad flat pack can be utilized. This features a rectangular or a square footprint, as well as pins that emanate from all the four sides. The pins are also bent from the package forming a gull-wing to ensure they come in contact with the board. The pins spacing depends on the required quantity of pins. There’s a need for great care when handling and packaging the chips. This is because these pins can be bent with ease.
Other Packages
There are other packages. One is the Ball Grid Array (BGA). This is utilized in so many applications. Rather than have connections on the package’s sides, they are placed beneath. The pads for connection feature balls of solder, which melt when soldering is on. This makes it connect well with the board and attach to it mechanically. As you can use the entire underside of this package, the connections’ pitch is wider. Also, it is seen as more reliable.
BGA has a smaller version, which is referred to as microBGA. This is also utilized for some integrated circuits. From the name, it is smaller compared to the BGA.
With the adoption level for SMT, there are different components available. Selecting components present in packages for surface mount by far surpasses the number present in the traditional forms. Purely, this is due to the demand.
The well-known basic components such as transistors and many analogue and logic integrated circuits like operational amplifiers usually have versions that come as both a component of traditional lead and surface mount. For example, the BC109 transistor can be gotten in the two formats.
How Does a SMT Manufacturer PCB Assembly Works?
SMT manufacturers conducting smt electronics manufacturing utilizing surface mount technology means they assemble their electronic components using automated machines. These machines place the components on a printed circuit board’s surface.
This contrasts the through-hole technology process that places the SMT components on a printed circuit board’s surface directly rather than soldering them to a wire lead. Regarding electronic assembly, the most used process is the SMT.
Electronic assembly covers not just the placement and the soldering of the PCB’s components, but deals with the production steps below.
- The application of the soldering paste (usually composed of flux and tin particles) to the printed circuit board
- Placing the components of the surface mount technology to the PCB’s soldering paste
- Using the reflow process to solder the boards
The Application of the Soldering Paste
One important step during the process of SMT assembly is the application of the soldering paste. The printing of the soldering paste is done on boards making use of the silk-screen technique. Depending on the board’s design, different stencils made of stainless steel for printing, as well as different pastes for specific products are utilized.
Making use of a stainless steel laser cut stencil, customized for the project, application of the soldering paste will only be done to areas on the components, where soldering will take place. After applying the soldering paste onto the boards, you then perform an inspection called 2D-soldering paste inspection. This is to make sure that the application of the paste is done correctly and evenly. Once the soldering paste’s application accuracy has been confirmed, then the boards will be moved to the line of SMT assembly. This is where the soldering of the components will take place.
Placing and Assembling the Component
Usually, all electronic components that need to be assembled usually come in reels or trays. Then, they are put in the SMT machine. While the loading process is on, intelligent software systems make sure that the components are not misloaded or switched.
The machine for SMT assembly then removes the components from its reel or tray automatically using a vacuum pipe. Next, it places these components on the board ensuring it stays on the right position. This they achieve making use of pre-programmed and precise X-Y coordinates. These machines can assemble about 25,000 components every hour. After completing the process of SMT assembly, then the boards will be transported to the Reflow ovens. Here, soldering takes place. This fixes the components on the board.
Soldering the Component
To help in soldering the electronic components, two methods are utilized here. Each of these methods comes with their unique benefits. This depends on the quantity of the order. You use reflow soldering for orders on series production. While working with this process, the boards are placed in an atmosphere containing nitrogen. Gradually, they are warmed using heated air until the melting of the soldering paste and the vaporization of the flux occurs. This helps in fusing the components to the printed circuit board.
After completing this stage, the SMT manufacturers cool off the boards. As the soldering paste’s tin hardens, its components fix to the board permanently. After this, the whole process involved in the SMT assembly is finalized.
For very sensitive components or prototypes, there is a special soldering process. Here, heating of the boards takes place till it reaches a particular melting point. This allows the soldering to be done at reduced temperatures. It also allows you to solder different components of the SMT at varying temperatures. However, this depends on what the soldering temperatures of these components are.
AOI and Visual Inspection
Soldering is regarded by smt manufacturers as the second to the final stage during SMT assembly. To make sure that the boards you have assembled are of good quality, or in order to find and correct any possible errors, you perform visual inspections to almost all the production orders. The AOI system utilizes several cameras and checks all the boards automatically. It does this, comparing each board’s appearance with the pre-defined and accurate image for reference.
If deviations are found during the inspection, the machine’s operator will be told of the problem. This operator will then correct the error and then remove the board to inspect it further. This AOI check helps in ensuring accuracy and consistency during the production process of the SMT assembly.
Role SMT Manufacturers Plays in PCB Design
One major reason that smt manufacturers shifted to surface mount technology was due to the rapid and great developments regarding reliability, speed, and cost involved in the whole process of PCB assembly.
Although, this is a significant impact for the technology’s adoption, it also has an impact on the development and design of new equipment and circuits. Fortunately, this recent transfer has brought in more benefits to circuit performance and development, compared to its disadvantages.
For the smt manufacturers, using surface mount technology gives several benefits. However, these smt manufacturers will need to watch some points.
Points to Note
Reduced power ratings
A surface mount component’s power rating is a very important factor to consider. A good example here is the resistor of the surface mount. Standard leaded resistors can dissipate a minimum of 0.25 watts. For a surface mount resistor, the bing will be much lesser, and the same goes for the dissipation. Users have to take note of this and check the data of the smt manufacturer.
Low spurious inductance and capacitance
Due to the component’s small size, the levels of capacitance and spurious inductance are usually smaller. SMT resistors work similarly to perfect resistors than leaded resistors. The same way, SMT capacitors will deliver a much reduced parasitic inductance. Due to this, it is possible to have higher frequencies and faster speeds with standard components of the surface mount technology compared to leaded equivalents.
Denser or smaller circuits
One common trend that goes around the world of electronics is the drive for extra functionality. This is very possible through the help of surface mount technology. There can be a great reduction in the size of the components. Also, they can be placed closed together on the PCB compared to when using traditional lead components.
Added to the higher functionality level, which is now found in integrated circuits, the task of smt manufacturers and development engineers is possible.
Although, there are some other precautions smt manufacturers need to take note of when using SMT for a new design, majority of the design’s elements will remain the same way, though the designs seems to be more complicated and offer more functionality. By so doing, the introduction and utilization of SMT by smt manufacturers has paved the way for electronics to develop, allowing greater complexity levels and offering more capability.
PCB Assembly Using SMT
Surface mount technology is exclusively utilized these days by smt manufacturers for the assembling and smt electronics manufacturing of printed circuit boards. The components of the surface mount are smaller, and most times, they provide a better performance level. Also, they can be utilized with the pick and place automatic machine, which will get rid of the work done manually during the process of assembly.
It is always difficult to place wired components automatically. This is because these wires have to be pre-formed so as to fit the required hole spacing. Today, during the process of PCB assembly by smt manufacturers, most components are placed on the board automatically. From time to time, some may require manual intervention, but all the time, this is reduced.
Traditionally, a few components and some connectors require some assistance with placement. However, the manual placement degree keeps falling. Today, PCBs are usually developed by smt manufacturers to help in reducing this to a minimum. This even gets to the point where smt manufacturers alter the PCB design, just to make use of components that they could place automatically. Asides from this, smt manufacturers have come up with specialized SMT components, which allows for the complete and automatic assembly for the majority of boards.
Some components give some issues, such as their heat resilience. To solder them, you will need to raise the temperature of the whole component to be raised high. Surface mount resistors, several surface mount capacitors, and integrated circuits are okay.
This is the reason why the use of surface mount electrolytic capacitors didn’t happen at first. Rather, it was the use of surface mount tantalums. However, today there have been new surface mount electrolytic capacitors that can tolerate any possible soldering temperature.
Board Flexure and Expansion
One possible issue with any surface mount board is temperature changes, as well as board flexing. Boards making use of leaded components won’t be a serious issue. This is because the component’s wires take the movement up and then relieves any possible strain that could be caused.
This may not hold true for any surface mount component. This is because the soldering of the components is done to the PCB, holding them tightly in place. Surface mount ICs and transistors have other means to accommodate movement. However, surface mount capacitors and resistors do not.
Several precautions must be taken by the smt manufacturers during the design and assembly of the printed circuit board. This is to make sure that problems of temperature expansion and warping are reduced.
Components shape
It is preferable to use surface mount components having wide, short bodies to thin and long ones. If these components are wide and short, the flexing and expansion effects will become less pronounced.
Make sure that the earth planes and PCB power are evenly distributed
When pcbs undergo soldering during the assembly of the PCB by the smt manufacturers, the boards will become well heated, which may cause warping. To prevent this from happening, power planes and earth planes should cover the board completely.
The components should be mounted at right angle to the maximum flex’s direction
Boards can warp usually along the board’s longest length. Therefore, make sure you mount byour components at a place that can be revealed to the minimum bend or flex.
Conclusion
SMT manufacturers play a vital role in the design of printed circuit boards. Rather than use the old traditional methods, these smt manufacturers make use of a more automatic approach, thereby getting rid of most manual methods
