Solder paste is a crucial material in the domain of modern electronic assembly technology. It is used for soldering electronic components onto printed circuit boards (PCBs), this enabling the creation of ever-evolving technological products.
The invention of solder paste played a pivotal role in the miniaturization of electronic product assembly technology. It transformed bulky devices, such as early large sized mobile phones, into pocket-sized, feature-rich smartphones.
The term “paste” in solder paste is used because its pre-melted form is similar in consistency to the toothpaste we use daily. Before soldering, the paste-like solder can be applied to hold electronic components in place on the surface of the PCB. This ensures that these components remain in position, even under slight vibrations. Its primary function, however, is to solder electronic components onto the PCB, facilitating the connectivity of electronic signals.
In the realm of PCB assembly, the go-to technology in SMT (Surface Mount Technology) is what we call “Full Board Reflow Soldering.” While there are other methods for assembling PCBs, this “Full Board Reflow Soldering” can be divided into two flavors: “Single-Sided Board SMT Reflow” and “Double-Sided Board SMT Reflow.” These days, single-sided reflow seems to be taking a back seat because double-sided reflow lets us save precious space on the PCB, making our products more compact. That’s why you’ll find most boards in the market are crafted using the double-sided reflow technique.
(By the way, if space isn’t an issue, the single-sided board process could cut down one SMT cycle. When you weigh material costs against SMT labor costs, single-sided might just be the more cost-effective route.)
With the rapid advancement of mobile communication technology, EMS (Electronic Manufacturing Services) providers worldwide are facing severe labor shortages. Furthermore, the Industry 4.0 trend has heightened the demand for automation in EMS facilities. As a result, many components that were previously not suited for Surface Mount Technology (SMT) are now required to meet the Paste-In-Hole (PIH) process. These components include Type A USB connectors, RJ45 Ethernet connectors, power sockets, transformers, and other relatively bulky parts. In the past, these components were typically soldered after SMT using wave soldering equipment or manual touch-up.
Due to the scarcity of manual labor and the need to save on subsequent manufacturing costs, along with quality considerations, many system manufacturers and EMS companies are gradually transitioning these non-SMT components to at least meet the PIH process requirements. This enables all electronic components to be soldered to the printed circuit board through a reflow oven.
What is an SMT Reflow Carrier? Why is it sometimes necessary in SMT production? And when do we need an SMT Full Process Carrier? Are there situations where neither is required?
The so-called “SMT reflow carriers or reflow templates” are essentially trays or carriers used to hold PCB (Printed Circuit Board) during the reflow soldering process. These carriers often feature positioning pillars to secure the PCB, preventing misalignment or deformation. Some advanced carriers even come with a lid, typically designed for Flexible Printed Circuit (FPC) use to avoid it from floating or lifting, equipped with magnets on both the upper and lower carriers acting as suction cups to firmly hold the board. This ensures the prevention of board deformation. In the case of rigid PCBs, a cover plate may also be used to secure specific components during the reflow process, preventing sliding.
This is a query from a user regarding SMT (Surface Mount Technology) processes, focusing on topics such as stencils, determining component placement sequence, and explanations of DFM (Design for Manufacturability) and DFX (Design for Excellence). We believe these questions and terms might also be of interest to those working in roles such as Project Management (PM), New Product Introduction (NPI), or procurement guys within electronic companies.
Often, when attending meetings with engineers, you may hear these technical terms without a clear understanding of what they actually mean. Not to worry, in this brief guide, we’ll attempt to explain these engineering terms in simpler language. Feel free to check back for updates if you have more related questions in the future.