When making pcb, should we still use through-hole components or smt chip components?

Today, smt patch assembly involves copper pads on the surface of the pcb. The components have no pins to penetrate the pcb. The robot can place tens of thousands of these tiny components on the pcb every hour.

Now, if 1 million mobile phones need to be sold every month, 48,000 components per hour can meet the requirement. But what about early-stage startups that may need 1,000 boards, or hobbyists with 100 boards, or a one-time design that only needs one or two boards? For people with such needs, should we still focus on smt patch components? Or should I stick to reliable through-hole components that seem easier to handle and solder?

I personally think that using surface mount components as much as possible, I do realize that doing so will complicate things, and some components only have through-hole packages. Sometimes the mechanical strength of the surface mount component is not enough to bear the weight of the component or the stress applied to it. In these cases, I will definitely choose the through-hole or through-hole/smt patch mixed method.

You may want to use through-hole components for several reasons:

1) Very large components, such as transformers, relays, and capacitors; either there is no corresponding surface mount package, or through-hole connectors are required to provide additional mechanical strength.

2) Connectors to withstand great mechanical stress.

3) If you feel uncomfortable with viewing and handling small smt patch components.

4) Just like through-hole packaging.

5) Only make a few pcbs and/or you have to use existing components.

In addition to the above points, despite the small size of the smt patch technology, there are many reasons to choose smt patch components when designing pcb. First of all, many new and state-of-the-art components do not have through-hole packages at all. If through-hole packages are persisted, many of the latest and most functional components will be excluded.
In the past few years, most chips have a variety of sizes to choose from, from a 0.1-inch (2.54mm) pitch through-hole dual in-line package (DIP) to the smallest through-hole package at the time. With such fierce competition today, coupled with a variety of specialized components, the cost of supporting so many packaging forms is becoming an important constraint. Many chip companies adapt to these market conditions by producing more practical and smaller packages.

The popularity of tiny Internet of Things (IoT) devices and mobile computing are important drivers of this trend. 3×3mm components can be used in micro IoT devices and large desktop systems. In contrast, 20-pin through-hole components and even SOICs that are not too small can only be used in desktop products, not IoT devices. Therefore, smt patch proofing or processing manufacturers may decide to only produce smaller component packages. You can find through-hole adapter boards for some of these components, but not all components.

The smt patch component is almost always cheaper than its through-hole version. This is for sure, the cost of components with much less raw materials will of course be lower, and this rule applies to many electronic components, especially passive components.

If mass production is planned, it is wise to start with smt chip packaging. In this way, there is no need to redesign the PCB between prototype and production, which can save a lot of time and money.

However, the biggest problem is cost. Because it needs to outsource the production and assembly of smt patch pcb, wouldn’t it be more expensive to use smt patch? Well, any time someone works for you, you have to spend money, but this trade-off is not so decisive.

Most people, with some patience, a good magnifying glass (or a magnifying glass for reading large magnifications), and something that can pad their wrists, can be hand-soldered in passive components in 0603 or 0402 packages. Some people even figured out how to manually solder QFN and BGA packages, but when the components are small enough, without special equipment, manual soldering is impractical (although it can be done).

If you have a pure hobby project, you will insist on using components that you can manually weld, set up a welding machine, or find a manufacturer that pursues low cost rather than high reliability. When what you are doing begins to become a career, then time is money. At this time, you can choose between time and money as needed.

The most important thing is, if you prefer through-hole components, you can use them as much as possible, and don’t need to be scornful. Just to be clear, you may not be able to use some of the latest and most powerful components, so I recommend using smt patch components as much as possible.

Post time: Oct-15-2020