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What & Why About China Turnkey PCB Assembly Solution

China Turnkey PCB Assembly

What is PCB assembly? I think it is the topic does not need to be repeated again, many people know it, which is a basic electronic industry. Nowadays you will often see the statement of turnkey PCB assembly in this areas, probably it is not a very clear topic for many purchasing and engineer guys, so here let's discuss this topic in more depth.

First, let's review some basic concepts

Difference between THT (Through-Holes Technology) and SMT

There are some key differences between PCB assembly techniques using THT (through-holes technology) and SMT. For example, SMT eliminates spacing constraints due to THT connections. Through-hole components typically have higher production costs than SMT.

SMT, on the other hand, requires different and often more complex design and production skills. Lower production costs are offset by high capital investment in machines that can process SMD. In addition, SMT components may have more pins than lead-based through-hole components.

SMT components are more compact; As a result, SMT designs have higher component density and lighter weight boards. In addition, because the board is more compact, it helps reduce electrical noise and sensitivity to electromagnetic interference (EMI). Best of all, eliminating the holes used for equipment connections can in turn reduce the number of holes needed for PCBs, thus speeding up production.

How does PCB assembly work in China factories?


Solder Paste

Solder paste needs to be added to the area of the PCB where solder is needed before adding components to the board. Typically, these areas are assembly pads. This is achieved using solder wire mesh.

Solder paste is a paste made by mixing small particles of solder with flux. This can be put in place in a process very similar to some printing processes.

Using a PCB stencil, placed directly on the circuit board and positioned in the correct position, solder paste flow moves across the stencil, squeezing a small amount of solder paste onto the board through holes in the stencil. Since the PCB SMT stencil is generated from the gerber file, it has holes in place of the pad so that the solder is deposited only on the pad.

The amount of solder deposited must be controlled to ensure that the resulting joint has the right amount of solder.

Pick and Place

During this part of the assembly, the board with solder paste enters the pick and place process. Here, the high-speed automatic machine with a component reel picks up components from a reel or other dispenser and places them in the correct position on the circuit board.

Elements placed on the plate are held in place by the tension of solder paste. As long as the boards don't wobble, this is enough to keep them in place.

During some assembly processes, the pick and place machine adds small dots of glue (red glue) to hold the component to the board. However, this is usually only done when the circuit board is wave welded. The downside of this process is that any repair is made more difficult by the presence of glue, although some glue is designed to degrade during welding.

The location and component information needed to program the SMT machine comes from the printed circuit board design information. This makes pick-and-drop programming much simpler.


Once the SMD component is added to the board, the next stage of assembly, the production process is to pass it through the welding machine. Although some boards may pass through a wave welder, this process is not widely used today for surface mount components. If wave soldering is used, no solder paste is added to the plate because the solder is supplied by the wave welder. Reflow welding is more widely used than wave soldering.


After the circuit board has passed the welding process, it is usually inspected. For surface mount boards with a hundred or more components, manual inspection is not an option. On the contrary, AOI (Automatic Optical Inspection) is a more feasible solution. AOI machines can examine circuit boards and detect bad joints, and misplaced components.


Electronic products need to be tested before they leave the factory. There are several ways to test them, in PS Electronics, what are covered are ICT (In-circuit Test), FCT (Function Test), reliability test, etc.


To ensure that the PCB assembly process is running satisfactorily, it is necessary to monitor the output. This is done by investigating any failures detected. The ideal location is the optical inspection stage, as this usually occurs after the welding stage. This means that process defects can be quickly detected and corrected before too many boards with the same problem are built.

So then, what is China turnkey PCB assembly?

Turnkey Solutions: Turnkey solutions are off-the-shelf solutions that can be easily deployed in an enterprise and actually require the end-user to simply "turn the key" to get started.

Turnkey solutions are useful for modern electronics companies that want to solve specific problems, but they have certain disadvantages: the unified products may lack the customization and integration required by today's enterprises; Especially those that are important to flexibility and scalability. They stand in stark contrast to custom-designed solutions created for companies. Turnkey solutions have pros and cons, depending on the business, size, industry, and decision-maker needs.

The reason most decision-makers evaluate why they need a turnkey solution is that they need to maximize the use of resources and save costs, the key point of whether to choose a turnkey service is that the decision-makers should weigh the opportunity cost. In general, turnkey PCB assembly is an advantage for small and medium-sized companies and startups in the electronics industry.

There are three characteristics of a true turnkey service provider


Consider the process your company uses when evaluating turnkey suppliers. Is it comprehensive? In PS Electronics, we start with a comprehensive assessment and carry it through to execution. We don't just treat the symptoms, we try to get to the root of the requirements and problems. This detailed assessment guides us through the engineering, manufacturing, and testing phases to provide you with holistic treatment rather than band-aid solutions.


The use of turnkey suppliers should eliminate the need for subcontractors. When you partner with a true full-service provider, your life should be easier -- your projects more manageable. Your turnkey supplier shall provide and manage all personnel required to complete the project. This means that you are dealing with one vendor, not a different contact for each part of the job.


The services of a true turnkey vendor should also include all the resources needed to execute the project. PS Electronics has a full A-Z in-house manufacturing workshop. From engineers to PM to on-call staff, we're ready to take care of every nuance of your project.

Before deciding to choose a turnkey solution provider

A turnkey solution is an integrated strategy that enables you to quickly and cost-effectively get the functionality your business needs. However, before choosing a turnkey solution:

1. Analyze your company's strengths and weaknesses: does this solution adequately complement the former and mitigate the latter?

2. Research the process that will change: does this solution demonstrate scalability, or does it need to be replaced if the business grows or shrinks?

3. Consider the employees or users who will primarily use this solution: how will it affect the way they work? Are you able to adequately train them during implementation?

4. Calculate the long-term cost of the solution: While the upfront costs may be low, are there potential hidden costs or additional expenses later?


A trustable China turnkey PCB assembly manufacturer for your customization

In PS Electronics, we take to heart our claim to be a professional PCB turnkey service provider. This is not an industry buzzword, but an ongoing commitment to our customers. Contact us now to learn why we are the EMS industry's total system solutions provider.


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