BQC is an experienced supplier of complete PCB Assembly.For all package types with over 16 years of industry experience in providing High-Quality PCB Assembly. For Surface Mount Devices (SMDs) of all sorts. In this article, we would like to offer our clients some insight into six common types of SMDs, including the standard applications of these package types, as well as their effects on the PCB Assembly Process.
SOIC & SOT
The SOIC (Small Outline Integrated Circuit) and the SOT (Small Outline Transistor) are perhaps the most common type of SMDs, and are included in a majority of SMT Assembly projects today. The SOIC can be considered the surface-mount equivalent of the classic though-hole DIP (Dual-Inline Package), while the SOT is a direct SMD equivalent to the legacy through-hole SOT package.
QFP
QFP (Quad Flat Package) components are most often used for microcontrollers, multi-channel codecs, and other moderately complex parts. They are generally considered the simplest option for high pin-count components, since the leads of a QFP are exposed and therefore relatively easy to inspect rework if necessary.
QFN
The QFN (Quad Flat No-Lead) package is similar to the QFP, with the notable difference that the electrical contacts of these devices do not protrude from the body of the component. This difference allows for QFN packages to be physically smaller than equivalent QFPs, but they do require some additional attention during PCB Assembly, and generally cannot be assembled reliably by non-professional methods such as Manual Assembly.
PLCC
PLCCs (Plastic Leaded Chip Carriers) are flexible options that allow for components to be mounted in a socket or soldered directly onto the PCB. These packages are particularly convenient for Prototype PCB Assembly projects, and especially those requiring IC Programming services. A socket can be used in the early iterations of the PCB, allowing ICs to be easily swapped in and out for testing purposes, and the smaller footprint of the IC itself can even be placed within the larger socket footprint so that no design change is necessary when your project moves into larger scale production.
PLCC sockets are normally treated as QFP-type components for the purposes of PCB assembly, while the PLCC components themselves are more akin to QFNs. As such, you should expect a slight difference in your PCB Assembly Quote when you switch to the more permanent solution of soldering your PLCC chip directly to the board. That being said, this cost is offset by the often considerable cost of IC sockets that will no longer need to be included on your BOM at this stage.
BGA
BGA (Ball Grid Array) packages are generally used for the most complex, high pin-count components on the market today, such as high-speed microprocessors and FPGAs (Field Programmable Gate Arrays). That being said, smaller BGA Variants such as the µBGA and DSBGA are sometimes used for simpler components for their smaller size compared to other package types. All BGA variants will require Reflow Soldering for their PCB Assembly , since the electrical contacts of these parts are located entirely beneath the silicon body of the IC.
POP
POP (Part-on-Part) technology refers to a process whereby specific components can be assembled directly atop one another. Most commonly used for memory modules and their associated microprocessors, this technique allows for significant space conservation in High-Sensity Interconnect(HDI) designs, as well as high-speed communication between crucial devices. The bottom device is normally a large BGA component with a high pin count, and a ring of additional BGA-style contacts on the top of the device, as shown in the image below.
These SMDs are also included in BQC's PCB Options at a Standard Price, and are treated just the same as any other SMD for the purposes of quotation and assembly. As with all SMDs, the number of pads included on the package will have some impact on the price of your quotation, but no additional cost is added for the simple existence of these component in your design. These parts can be assembled using standard Reflow Soldering, and inspected using AOI in tandem with multi-stage Visual Inspection.
