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How to Have EMS PCBA Manufactured at One-Stop Hassle-Free

pcbonline PCBONLINE Team Tues, Aug 23, 2022

With EMS PCBA services, you can have electronics manufacturing by a third-party manufacturer. You can save enormous resources and costs because you don't have to build production lines and hire and manage workers anymore. And you can upgrade products without considering fabrication capabilities. All you need is to keep your R & D capability and brand marketing.

EMS PCB assembly

This article reveals EMS PCBA and how can you have EMS PCBA manufacturing without hassle at one-stop.

Part 1: What is EMS PCBA

EMS stands for electronics manufacturing services or solutions, and PCBA stands for printed circuit board assembly.


A PCBA is the main component of all modern electronic and electrical devices. A printed circuit board is manufactured according to your design and assembled with electronic components to create a PCBA. You can make PCBAs assembled or connected to group a larger PCBA for a complex product or system. When the PCBA is assembled with its mechanical box, you get a finished electrical product.

From this aspect, electronics manufacturing is no wonder PCBA manufacturing, and EMS PCBA is no wonder turnkey PCBA. We can consider a new-energy car, a computer, a mobile phone, and so on as PCBAs that are assembled with their mechanical box. In fact, they are.

Part 2: What to Prepare for an EMS PCBA Manufacturer

To have EMS PCBA manufactured from a third-party manufacturer without too many back-and-forths, you will provide the below materials together to get a quote:

1. Gerber

A Gerber is generated automatically from a PCB design software when you complete a PCB design. It is a universal PCB design compressed file, which contains a Gerber file folder and a drill file folder. In the Gerber folder, each PCB layer (solder mask, circuit layer, prepreg, substrate, and silkscreen) corresponds to a graphic file.

2. Bill of materials (BOM)


A BOM is a component list that contains all information on electronic components for EMS PCBA assembly, including the component reference, quantity, footprint, part number, manufacturer name, and manufacturer part number (optional).

Gerber and BOM are necessary materials you will need to provide with your EMS PCBA manufacturer. If you also provide these materials, you can make it easier for your manufacturer to conduct EMS PCBA manufacturing.

  • Pick-place file - it lists the references of the components on the board so that the EMS manufacturer can compare the real PCBA with it. This file, in fact, can also be generated by your EMS manufacturer.
  • Assembly drawing - it shows the estimated PCB assembly.
  • 3D drawing - it displays the three-dimensional outlook of the estimated PCB assembly.
  • Schematic - it allows your EMS manufacturer to debug possible issues during the fabrication process.
  • Testing file - is used for finished product testing, including testing methods and procedures.

3D drawing for EMS PCBA

Part 3: EMS PCBA Manufacturing at One-Stop

PCBONLINE, a one-stop EMS PCBA manufacturer founded in 1999, provides PCB design, prototyping, manufacturing, assembly, and value-added services, such as conformal coating, IC programming, mechanical boxes, and box-built.

Below is how can you have EMS PCBA manufacturing from the beginning to product delivery.

PCB Design

When you design a PCB, you will draw schematics, design the stack-up, size, and layer number, and set up the routing width rules, fanout control rules, routing via style rules, routing layers rules, and electrical clearance rules. You will follow some design rules - placing big and main components first and in the center with small components around, fanout the big and main components first, separate analog and digital signals...

PCB design

The wires will route automatically based on the rules you set up. When it completes, you will check the wire routing.

If you need help in PCB design, please feel free to contact PCBONLINE in your early developing phase. Our CAM engineer with 20+ years of experience will provide you with one-on-one assistance.

Once receiving your Gerber, the manufacturer PCBONLINE will review it to make sure your design can be fabricated in theory.

PCB Prototyping and Assembly

The PCB design is only feasible in theory, but in fabrication, even a small detail that we didn't consider can fail the product. Before batch EMS PCBA production, the manufacturer PCBONLINE will prototype first.

PCB prototype

By prototyping, we can test out our ideas and different materials until we finally get the optimal design and successful samples.

Please note that if you order bulk EMS PCBA from PCBONLINE, we will offer you a free PCBA sample, including PCB prototyping, prototype assembly, and the electronic components for it.

PCB fabrication

PCBONLINE has two large advanced manufacturing bases, and we can fabricate FR4 PCB, flexible PCB, rigid-flex PCB, metal core PCB, high-frequency PCB, AlN PCB, alumina PCB, and hybrid PCB.

The PCB fabrication process includes the below steps (take FPC fabrication for example):

Process FPC copper and coverlay fabrication

fabricate FCCL and coverlay

We press the ED or RA copper foil, polyimide (PI), and adhesive to the required thickness. And we laminate the PI and adhesive to make the FPC coverlay.

Laminate fabrication and drilling

FPC lamination

We laminate the ED or RA copper foil with coverlay to fabricate the FPC laminates. Then we drill on the laminates and coverlays.

VCP electroplating and circuit image transfer

VCP FPC fabrication

On the VCP line, we electroplate the PCB through holes. And then, we transfer the circuit image on the copper foil by UV exposure.

Circuit etching and drilling positioning holes

FPC circuit etching

On the circuit etching line, the unwanted copper is chemically removed, and the copper foil becomes circuit layers.

Then we drill positioning holes on the laminates and coverlays so that the board can be laminated and assembled efficiently.

Electrical testing and cleaning of FPC

FPC electrical test

After etching, we conduct an electrical test on every circuit layer. Later, we clean and scrub the FPC laminates to increase the gloss.

FPC lamination, silkscreen, and baking

FPC lamination for EMS PCBA

Later, we stack the laminates and coverlay according to your PCB stack-up and laminate them at high temperatures. Then we print PCB inks on the FPC for silkscreen. Later, we bake the FPC boards.

Surface finish, electrical test, and forming FPC

forming FPC

Next, we apply the surface finish according to your requirements and conduct an electrical test on the boards.

Then we form the finished FPC boards by cutting the rail edge by cutting dies and steel dies.

Visual inspection and sample testing

FPC visual inspection

Finally, we conduct a visual inspection on all FPC boards and randomly pick up 10% of the boards for sampling testing.

If all samples pass the testing, then we package the boards. If even a sample board fails in testing, we test all the rest boards to make sure the circuit board quality.

During PCB fabrication, the SMT stencils and jigs for PCB assembly will also be fabricated by the PCB manufacturer.

Sourcing electronic components

electronic component sourcing

Once you place the EMS PCBA order, we start sourcing electronic components. It takes about 15 to 45 days for PCBONLINE to source all passive and active components for PCB assembly.

Relying on our EMS production factory, we can enjoy direct supplies from the original factories and enjoy discounts by co-procurement with other large EMS.

Besides, we have long-term strategic cooperation with authoritative suppliers, such as Digi-Key and Mouser.

If you want odd components, we can also have them manufactured from local factories in Shenzhen.

All the suppliers have been audited by us. For ICs, we conduct a counterfeit test to make sure they are real ICs.

PCB Assembly

At PCBONLINE's PCB assembly factory, both SMT and THT assembly are available. Before bulk PCB assembly, we assemble five pieces first and randomly choose one PCBA for the first article test. We will generate a PCBA sample testing report for you to review and approve bulk PCBA production.

The SMT PCBA manufacturing process is below.

Solder paste printing and inspection

SMT solder paste printing

A solder paste machine is the beginning of an SMT line. At first, a feeder automatically sends the PCBs into the solder paste printing machine, which has already been placed with an SMT stencil. The scraper of the machine presses the solder paste to go through the stencil holes to "print" on the PCB pads.

Later, the PCB is automatically sent into a solder paste inspection machine to make sure the solder paste positions, shapes, and sizes are qualified.

Surface-mount SMDs on PCBs and BGA x-ray inspection

surface mounting SMD

On the SMT line, the PCBs are one by one sent into the high-speed and functional surface mounting machines, in which the SMDs are pick-and-placed on PCB pads.

If your PCBA has BGAs, we have to use an x-ray machine to inspect the solder balls under the BGA before reflow soldering.

Reflow soldering and AOI inspection

reflow solder PCBA

The PCBAs are automatically transferred into a reflow soldering oven with 10 temperature zones, where the boards are preheated, reflow soldered, and cooled down. The moisture and flux of the solder paste evaporate. The alloy powders in the solder paste and BGA solder balls gradually melt and bond the PCB and SMDs and cure.

Later, the PCBAs pass the automatic optical inspection (AOI) machine one by one. The AOI makes sure there are no surface issues, such as bridges, insufficient soldering, SMD offsets, skew, and missing.

After the SMT assembly, if the PCBAs need THT assembly, they will be assembled on the THT assembly lines.

Through-hole mounting and wave soldering

wave soldering PCBA

We manually insert the pins of through-hole components through the PTHs and deliver the PCBAs into a preheating machine. The preheated PCBAs are automatically transferred in a wave soldering machine, in which liquid tin fills the gaps between the pins and PTH hole walls.

Then we trim the pin length to be within 2mm and visually inspect the PCBAs. Then we clean the PCBAs.

For many manufacturers, the PCBA production ends now, and they will send you the PCBAs. But the EMS PCBA manufacturer PCBONLINE continues working in the post-assembly phase.

PCBA Post-Assembly Phase

PCB assembly post-phase

After PCB assembly, we conduct functional jig testing on all the PCBAs to make sure the product work as expected.

And we provide the below value-added services.

  • IC programming - we have standard IC programming jigs and can transfer the program into the ICs on circuit boards freely for you. However, you will need to provide the program. If you don't want your EMS PCBA manufacturer to download your program, you can give us a cloud interface, which allows you to control and monitor every program transfer from the cloud to the IC without downloading to the local of our computer.
  • Conformal coating - we can apply conformal coating on the PCBAs to provide better protection and extend the lifespan of the electronic and electrical products.
  • Thermal aging testing - we can let the PCBA power on continuously for 48 hours or more to make sure your electrical products perform well for a long working period in use.
  • Box-built assembly - we can design the mechanical box according to your requirements and have them manufactured by local factories in Shenzhen. And later, we assemble the PCBAs with the corresponding mechanical boxes. Finally, we will conduct finished product testing to make sure the box-builds work normally. And we package and have them shipped to you.

PCB assembly services from PCBONLINE

All EMS PCBA prices for the paid services will be clearly listed on the quotation order from PCBONLINE. And our CAM engineer will provide free one-on-one engineering assistance throughout the project. Besides, this fourth quarter, PCBONLINE will provide 35% off for bulk PCB fabrication and 15% off for EMS PCBA orders. You can contact PCBONLINE by email at info@pcbonline.com to activate this promotion.


EMS PCBA manufacturing can be easy, quick, safe, and hassle-free. This article illustrates how you can have EMS PCBA manufactured saving time and energy. By working with the one-stop EMS manufacturer PCBONLINE, you can also save big and harvest high-quality products.

© This article is an original work of the PCBONLINE team. Please indicate the author PCBONLINE if you reprint. If the article is reproduced without permission or indicating the author's source, PCBONLINE reserves the right to investigate the infringement.


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