Is Your EMS Provider Experienced Enough?

Working with a new, unproven vendor is a big risk. Essentially, you will be their guinea pig, helping them to work out all the kinks in their system. That’s a great opportunity for them, but not so much for you! That’s why it is so important to know how long a company has been in business before you decide to work with them. Any company that has been around for at least five years is likely to have their systems down and to have confronted a wide variety of issues and challenges that they can now address with ease.

When it comes to electronic contract manufacturing service (EMS) providers, even more experience can be useful. Technology changes so rapidly that any EMS provider who has survived ten years or more has shown that they can continually adapt along with the printed circuit boards they work on.

At Yun Industrial and ACME PCB Assembly, we have been in business for over 28 years! We have proven our ability to work with a wide variety of clients and to keep pace with changing technology. Contact us today if you want to work with an experienced contract manufacturing service provider.

Common Terms for PCB Assembly Services

February 2, 2022 by Marilyn

What the Heck Is Your PCB Vendor Talking About? – Common Terms for PCB Assembly

Every industry has its established lingo, which helps its members communicate more efficiently. If you are on the outside looking in, however, it can seem like they are speaking a foreign tongue. This becomes a problem when you need to work with vendors on ordering printed circuit boards for your device or your prototype. If you’ve gotten lost while trying to speak to your vendor (SMP, SME, SMD?), then you’ve come to the right place. Here is our no-nonsense guide on the most common terms in the printed circuit board industry:

  • PCB – Stands for Printed Circuit Board. Printed circuit boards are found in every single device that uses computing and data. PCBs act as the “highway” in transferring data between components within a device.
  • THM – Stands for Through-Hole Mounting (also known as Thru-Hole Mounting). THM is an older assembly technology that mounts components on a PCB by drilling holes through the PCB and placing component leads into them. This has largely been replaced by SMT assembly, though there are still some situations in which THM is preferred.
  • SMT – Stands for Surface Mount Technology. SMT was first introduced in the 1960s and rose to prominence in the 1980s. Today, it is the dominant form of PCB assembly. SMT does not require drilling holes through a printed circuit board. Its components are smaller than THM and can be placed on both sides of the PCB. This allows for a denser allotment of components and a more powerful PCB.
  • Substrate – The substrate is the actual board upon which wires and components are placed. It gives the PCB its structure and also insulates conductive parts. PCBs can be made from a variety of different substrates. All PCB substrates are non-conductive. Common substrate materials are: FR-4 (a fiberglass-epoxy laminate), Teflon, ceramics, specialized polymers
  • Traces – Traces are the things that electrically connect the connectors to the components. The most common material for the traces is copper. The copper layer of a PCB goes on top of the substrate. In double-sided PCBs, copper traces are placed on both sides of the PCB.
  • Soldermask – Have you ever wondered why almost all PCBs are green? This is the soldermask. This layer goes on top of the copper layer and functions to insulate the copper traces. It prevents the highly conductive copper traces from making contact with other metal components of the PCB.

While this is far from an exhaustive list of common terms used in the PCB industry, hopefully this guide will help you better understand and communicate with your printed circuit board manufacturer.

Contact Us for a quote.

Circuit Board Design Service

A circuit board designer must design and create the layout of the circuits, before a circuit board can be populated. The circuit board designer must follow certain standards, such as not violating the minimum electrical clearance. This way, the finished printed circuit board, (PCB), can function as intended in an efficient manner.

This design service is usually done by an electrical engineer. The designer uses layout software to integrate both the component placement and routing to determine ideal electrical connectivity. The engineer would create a schematic to check that it follows all functional and mechanical requirements. But this is not a job anyone can do. Some common problems amateur PCB designers have are creating incorrect landing patterns, substandard layouts, insufficient width for traces, and creating blind/buried vias that are impossible to manufacture. Fortunately for you, we are not amateurs.

Founded in 1990, ACME PCB Assembly has decades of experience in the field of circuit board services. By looking at what product your company produces, we can identify which circuit board designer is best for you. ACME partners with several designers that all specialize in different fields. This is important if your board needs wireless capabilities or a specific power input. We can also make sure that your design is cost efficient where it needs to be. Having too many layers in a PCB can be expensive. But leave these worries with us: we are professionals.

Whether you’re in the stages of designing a circuit, fabricating a board, assembling PCBs, or conformal coating, ACME can be there to support your team.

What is PCBA (PCB Assembly)?

What is PCBA?

PCBA, (Printed Circuit Board Assembly), is the finished product after components have been bonded to a PCB, (Printed Circuit Board). These components can range from resistors and diodes to transformers and integrated circuits. The PCBA process tends to include a reflow furnace to heat the printed solder paste so that the components are formed onto the board.

The term PCBA is sometimes confused with the term PCB. PCB, in terms of circuit layers, is classified as either single layer, double layer, or multilayer. These boards can also be divided into a category: flexibility. There are 3 types of PCB in terms of flexibility, such as rigid board, flexible board, and flex-rigid board. This is different from the term PCBA since it is not a tangible object but rather a service. This service usually includes using SMT and DIP technologies so that all the components and parts are soldered/mounted on a PCB.

The most basic PCBA process has three steps. It begins with a solder paste printing station. This is where solder paste gets printed onto the boards. After pasting, the components are placed on the board by a pick-and-place machine. When all components have been planted, the board is then ran through a reflow oven so that the board can be completed.

Normally, the assembly process ends here. At ACME, we also include wave soldering, selective soldering, machine and visual inspection, and cleaning. One of the latest Nordson selective soldering machines is used to accurately solder in partially assembled PCBs. Our 3D AOI machine from YesTech inspects the components on the boards using not only the length and width, but also the height. This can check for correct solder heights, proper wetting, and missing components. Our quality check inspectors review the images to make sure the board passes IPC-A-610 standards.

For more information and the services ACME PCB Assembly provides, call (310) 715-1898 or visit our website at

What is SMT Assembly?

SMT, or surface-mount technology, is a method where the components are mounted or placed onto the surface of a PCB, or printed circuit board. There are some components that are unsuitable for SMT assembly, such as large transformers and heat-sinked power semiconductors, but other processes can handle them. Employing this technology speeds up the production process but the catch is the risk of defects due to component miniaturization and denser packing of boards. SMT assembly is also highly dependent on automation and medium to high-scale production. Here at ACME PCB, we can work with components as small as 01005 and assemble high quantity boards to low quantity boards.

SMT assembly can be done on both sides of a PCB. The SMT process starts off with a screen-printing process that applies solder paste onto all the solder pads. These solder pads are where the components are placed. The pads are normally flat and made from either tin-lead, silver, or gold-plated copper. After the board is pasted, it is placed onto a conveyor belt and sent to a pick-and-place machine. These components are sometimes in static free trays or plastic tubes.

The last step in the SMT assembly process is the reflow soldering oven. The solder particles in the solder paste are melted. This makes the component bond to the solder pads. At ACME PCB, we make sure to check each board for defects and errors before sending them to the reflow oven. After the heating process, the boards are put into our in-line washer to remove any traces of white residue, dirt, and other contaminants. If any leadless parts are used, they are inspected using our X-ray machine to ensure solder joint quality.

For business inquiries or quoting services, call ACME PCB Assembly at (310) 715-1898 or visit our website at

ISO 14001:2015 Certification


ACME PCB Assembly is proud of achieving the ENVIRONMENTAL MANAGEMENT SYSTEMS – ISO 14001:2015 certification. A great effort was made to accomplishing this.

ISO 14001:2015 specifies the requirements for an environmental management system that an organization can use to enhance its environmental performance. ISO 14001:2015 is intended for use by an organization seeking to manage its environmental responsibilities in a systematic manner that contributes to the environmental pillar of sustainability.  We strive to not only work hard, but to work towards the future.

Precision Wire Stripping at ACME PCB Assembly

Jacket Slitting

Does your project require wire-jacket slitting?  ACME PCB ASSEMBLY can slit the jackets of  wire diameters from o.1″ to 1.0″ (3-25 mm).  Slitting can be either radial, or radial and axial.   Wires can be out-of-round or twisted.

Watch how it’s done:

Stripping Cable Ends & Windows

Do you require wire stripping of cable ends or windows?   ACME PCB ASSEMBLY can strip wire sizes from 32 AWG to 2/0.

Watch how it’s done:

Stripping Multi-Conductor and Large Diamenter Wires

ACME PCB ASSEMBLY can strip multi-conductor cables and large diameter wires such as battery cables in  wire sizes from 32 AWG to 2/0.

Watch how it’s done:

Rotary Stripping Coaxial Cables

ACME PCB ASSEMBLY offers precision rotary stripping of coaxial cables and wires with outer diameters up to 0.43″ (11 mm) and stripping lengths up to 1.58″ (40 mm).

Watch how it’s done:

Reworking large PCBs


ACME PCB Assembly utilizes an Ersa IR/PL 650 XL for reworking large PCBs

Reworking large PCBs can be extremely difficult. But with the IR/PL 650 XL BGA rework machine, ACME PCB can now safely handle even the toughest requirements.

The IR/PL 650 XL BGA rework machine gives ACME PCB Assembly the flexibility to work on many projects including extra-large printed circuit boards (PCBs) up to 20″ x 24″ (500 mm x 625 mm).

The IR/PL 650 XLis Ersa’s flagship machine with one of the industry’s largest and most powerful bottom-side heaters – an 8,000 W medium wavelength IR heater measuring 500 mm x 625 mm.