SMT Assembly

Surface Mount Technology (SMT) is one of the two PCB assembly technologies (another one is through-hole technology), is a modern PCB assembly approach, in which electrical SMD components are mounted directly onto the surface contact pads of a printed circuit board (PCB), and that’s also why surface mounting was originally called planar mounting.

 

 

MADPCB is an experienced SMT assembly house, providing solutions for all types PCB assembly, including rigid, metal core, flex and rigid-flex, to many across a multiple of industries. We have been assembling SMT designs for over 10 years now, and we take pride in the prototype, low– to high-volume PCB assembly we perform through our highly trained professional assembly engineer, technicians and advanced assembly lines. We always work with your design in mind, and keep you updating of your PCB assembly project that work with us.

 

SMT Assembly vs. THT Assembly

 

An electrical component mounted with SMT assembly manner is referred to as a surface mounting device (SMD). In PCB assembly industry, SMT assembly approach has largely replaced the through-hole technology (THT) construction method of populating components, in large part because SMT allows for increased manufacturing automation which reduces cost and improves quality -it allows for more components for fitted to a given area, especially when electronic devices are in pursuit of size miniature. Both technologies can be used on the same board at the same time, with the thru-hole technology (THT) often used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors.

As SMT component is usually smaller than its thru-hole counterpart because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls (BGAs), or terminations on the body of the component.

 

What We Can Assemble?

 

Today, surface mounting is the main technology used for PCB assembly within electronics manufacturing. SMD components are able to be manufactured in very small, and may types are used in their billions, particularly SMT capacitors and SMT resistors. There are styles of package components, transistors and diodes, and integrated circuits (ICs).

 

• Passive SMDs: There is quite a variety of different packages used for passive SMDs. However, the majority of passive SMDs are either SMT resistors or SMT capacitors for which the package sizes are reasonably well standardized. Other component including coils, crystals and others tend to have more individual requirements and hence their own packages.

 

• Resistors and capacitors have a variety of package sizes. These have designations that include: 1206, 0805, 0603, 0402 and 0201. The figures refer to the dimensions in hundreds of an inch. The larger size such as 1206 was some of the first that were used in SMT assembly. They are not in widespread use now as much smaller components are generally required. However, they may find use in applications where larger power levels are needed or where other considerations require the larger size. The electrical connections of these SMD components to the PCB are made through metallized areas at either end of the package. For passive parts, we can work with chip packages as small as 0201.

 

• Transistors and Diodes: SMT transistors and SMT diodes are often contained in a small plastic package. The connections are made via leads which spread from the package and are bent so that they touch the PCB board. Three leads are always used for these packages. In this way, it’s easy to identify which may round the device must go.

 

• Integrated Circuits (ICs): There is a variety of packages which are used for integrated circuits. The package used depends upon the level of interconnectivity required. Many chips like the simple logic chips may only require 14 or 16 pins, whereas other like the VLSL processors and associated chips can require up to 200 or more. In view of the wide variation of requirements, there is a number of different packages available.

 

• For the smaller chips, packages such as the SOIC may be used. These are effectively the SMT version of the familiar DIL packages used for the familiar 74 series logic chips. Additionally, there are smaller versions including TSOP and SSOP.

 

• The VLSL chips require a different approach. Typically, a package known as a QFP is used. This has a square or rectangular footprint and has pins spreading on all four sides. Pins again are bent out of the package in what is termed a gull-wing formation, so that they meet the PCB board or FPC. The spacing of the pins is dependent upon the number of pins required. For some chips, it may be as close as 20 thousand pcs of an inch. Great care is required when packaging these chips and handling them as the pins are very easily bent.

 

• Other packages are also available. One known as BGA (Ball Grid Array) or μBGA is used in many applications. Instead of having the connections on the side of the package, they are underneath. The connection with the board and mechanically that melt during the soldering process, thereby making a good connection with the board and mechanically attaching it. Like QFN, PLCC, DSBGA and PoP.

 

• And various other small chip packages that have a pitch of 0.2mm (8mil) or larger. Thru-hole parts are also no problem at our SMT house. With advantages of our PCB assembly capabilities and supply chain management, MADPCB also offer customers who are in demand of turnkey PCB assembly service.

 

Work with SMT Assembly Professional at MADPCB!

 

MADPCB’s PCB Assembly Process is carefully matched to your design and your specific constraints, so you can reset assured that your SMT parts will be soldered flawlessly every time. We will review the SMT PCB assembly design you submit during our DFM, DFA stages, and we might feedback some suggestions, but you are always in complete control of the project. We will happily work with your engineers in order to produce exactly the SMT assemblies you need. We thoroughly review and follow the reflow surface mount soldering requirements of each individual SMD component for each assembly job we undertake. We have a very high yield as we implement precise control of the reflow soldering process.

In order to detect the joint soldering SMT quality, we employ a variety of verification and inspection methods, including repeated Visual Inspection, AOI and X-ray Inspection. For leadless parts such as QFN, DFN and BGA packages, there is no way to perform a direct visual inspection. By using X-ray inspection, many of the issues with SMT soldering can be detected -this is important for BGA assembly projects.

We would be gratefully work with you on your PCB assembly project and offer whatever help we can, regardless of where you are in the design process. We can provide DFM advice from the earliest stages of your design. Once your project advances, we’ll give you quick turnaround times for prototype and maximum flexibility for your production runs. Contact MADPCB now for a quick quote on your SMT assembly job!