5 A B C D E F I L M N P R S U W

5S = “Sort. Set in Order. Shine. Standardize. Sustain.”

Sorting involves placing tools, supplies and other items needed in the manufacturing process in appropriate areas.

Appropriate areas would mean placing infrequently used tools further away from frequently used ones. Sorting also includes establishing areas on the production floor to store product that is in a certain stage of development. Sorting not only makes the work environment more efficient, it also improves safety by establishing rules such as not storing material above a certain height.

Set in Order
Once tools/items/material/product has been sorted, the designated storage areas are “set in order” frequently by color coding. This includes not only color coding storage bins but also color coding the floor with colored tape.

Every single work day there is set aside a period of time to clean. Having clean and shining work areas help workers produce more effectively and helps extend the life of production equipment.

Once a company has determined what works best for the previous 3 steps, the next step is to create a standard that all employees must follow. Frequently this standard is displayed on the production floor and in the warehouse so that all employees will understand what goes where and when. The image shown to the right is Futaba’s 5S standard that we have on display throughout our plant.


This concept means that a company must never cease to following the previous steps. Each employee must press on and daily follow the established standard in keeping a clean, organized, and safe working environment. To summarize all this succinctly, consider 5S to basically mean being disciplined to keep things clean and organized.

AOI = Automated Optical Inspection

An AOI machine is a machine that uses camera(s) and special lighting to visually inspect a printed circuit board assembly during the manufacturing process. Such machines are good at detecting missing, skewed, flipped, and unsoldered parts.

APQP = Advanced Product Quality Planning

Is a highly structured process that is followed to assure delivering quality product to a customer (typically an automotive customer). The focus is not only on the manufacturing process to assure quality product is built, but attention is also given to all areas – such as material procurement and shipping.

AQL = Acceptable Quality Limit (or, Acceptable Quality Level)

An acceptable quality level is an inspection standard used mostly with large production runs. It describes the maximum number of defective units in a production run when samples are randomly taken. The AQL standard will help quality personnel know how many units to inspect in a given shipment, and the number of defective units that will trigger a “fail” condition. A “fail” condition could mean rejecting the entire shipment of parts.

ATE = Automated (or, Automatic) Test Equipment

A machine used in the manufacturing process to electrically test boards to confirm that they were manufactured correctly. An ATE is normally used to test the functionality of the manufactured boards. Whereas an ICT (another acronym described later) is mostly used to perform parametric testing. Parametric testing means confirming that the correct part type was placed on a circuit board – something that ATE mostly cannot do.

ATE is also called by another acronym: EOLT. EOLT stands for Electronic end Of Line Test. ATE and EOLT are both functional tests. We have a detailed article on electronic function test here.

BOM = Bill of Material

A BOM is a list of materials needed to produce an electrical assembly. At a minimum a BOM contains: a part number, a source, a source part number, and a reference designator (where to place the part on the circuit board).

CAR = Corrective Action Report

This is a document created by a part manufacturer for the manufacturer’s customer in response to a defect being found by the customer. The document describes the root cause of the defects and the steps that have been taken to prevent this type of defect from occurring again.

CC = Conformal Coating

Conformal coating is a thin coating of clear material that is sprayed on electrical assemblies to protect them from moisture, dust, and certain chemicals. As the coating is sprayed, it conforms to the shape of the components on the board. Normally CC is only applied on those assemblies that will be used in harsh environments. We have a detailed educational article on CC here.

CM = Contract Manufacturer

A CM manufactures products for a customer. A CM in the electronics industry manufacturers and assembles electronics. Normally a CM does not build and sell their own products but builds products designed by their customer.

Cpk = Process Capability Index

A Cpk value is a numeric value that describes how closely a manufacturing process or manufactured assembly meets its specification. A Cpk value greater than 1 indicates that the process or assembly meets the specification.

DFM = Design for Manufacturing

Design for Manufacturing is the process of studying the design of a circuit board assembly with the purpose of improving it in ways that can reduce the probability of manufacturing defects and reducing the manufacturing costs.

A circuit board design can be perfect from a purely electrical engineering point of view. However, it can be a very poor design with respect to manufacturing. Let’s look at an example: let’s say we have a circuit board that has a handload capacitor in the middle of the board. Let’s also say that there is a diode near the PCB’s breakaway (area between copies of a circuit board in a PCB panel) region. When studying this circuit board for DFM, we see 2 issues: 1) the handload capacitor should be replaced with a machine-placed SMT capacitor. Using a human to handplace a capacitor costs much more than having a machine do it; 2) having the diode near the edge of the PCB could result in the diode getting damaged when the boards in the panel are separated.

DUT = Device Under Test

In the electronics contract manufacturing industry, a device under test is a circuit board that is undergoing electrical testing.

DV = Design Verification or Design Validation

During the prototype stage of an assembly, an EMS will have what is called a “DV build” for the customer. During the DV build, units are produced for the customer so they can closely analyze (electronically, physically, and cosmetically) the units to see if the design is ready for mass production, or if the design needs to be modified.

Some companies refer to the above process as “Design Validation”. So, depending on who you talk to, DV may mean “Design Verification” or “Design Validation”.

EAU = Estimated Annual Usage

This term is frequently used in quoting. When a customer requests a production quote from an EMS, the EMS will want to know the customer’s EAU. Similarly, when an EMS contacts various suppliers to obtain quotes for parts, the suppliers will want to know the EAU of those parts.

ECN = Engineering Change Notice
ECO = Engineering Change Order

An Engineering Change Notice is a document that describes changes being made to a customer’s product, or changes to a process in the making of a customer’s product. Usually, an ECO will include a revision number as well as a signature block where various representatives from the customer and the manufacturer can sign to indicate their approval of the change(s).

EMS = Electronics Manufacturing Service

An EMS is a company that will manufacture electronic assemblies for other businesses that do not have the capability to do so.

EOLT = End of Line Test

An end of line test refers to the testing of electronic circuit assemblies at the end of the manufacturing process. A circuit board may undergo testing at various stages in the manufacturing process, but an end of line test is the final testing point before a unit is boxed up in preparation for shipment to a customer.

Usually an end of line test is a functional test. That is, a board’s functionality is tested. Read more here.

ERP = Enterprise Resource Planning

When someone refers to their “ERP system”, they are referring to a large software package that helps employees in multiple departments (hence the word “enterprise”) perform job functions such as:

  • Entering and tracking of customer orders
  • Budgeting
  • Resource planning
  • Inventory management
  • Human Resource functions
  • Shipping
  • Receiving
  • and numerous others

The ERP acronym evolved from the MRP acronym. MRP stands for Manufacturing Resource Planning. An MRP system typically resided on a local server at an EMS company. Whereas an ERP system is usually cloud-based and has more capabilities.

ES = Engineering Sample

An engineering sample is no different than a prototype. Frequently, for new designs, an EMS will be called upon to manufacture a small amount of a newly designed product for a customer. The purpose of these samples is so that the customer can scrutinize not only the design of the product but how well the EMS built it before mass production starts.

ESD = Electrostatic Discharge

Electrostatic discharge is the flow of electricity between objects that are at different voltage levels.

Most of us have had experiences with ESD – for example, getting shocked when you touch a doorknob after walking across carpet on a dry winter day. Many electrical components (especially integrated circuits) are extremely sensitive to ESD. ESD can permanently damage electronics. EMS companies must have very good protective measures in place so as to minimize the potential of an ESD event.

Most know that the shock one feels when shocking a doorknob on a winter day is bad for electronics, but most do not know that some electrical components are so sensitive to ESD that it is possible to damage them without even feeling “shock”.

FAI = First Article Inspection

Before a supplier will produce more of a new or revised part, the supplier would like to get the purchaser’s agreement that the supplied part will meet the purchaser’s expectation. For such parts, the supplier will provide a First Article Inspection document that lists – among other things – the supplier’s part number, the customer’s part number, the description of the part and a signature block for the purchaser to sign, which would indicate approval.

In the EMS industry, it is most common for programmed IC vendors to provide a FAI report for the initial samples of a programmed IC. The purpose of this is so the supplier can be confident that they programmed the IC correctly.

FCT = Function test

A function test tests the functionality of an electronic assembly. The purpose of this test is to see if the assembly will behave (or function) in a way that the customer expects.

FG = Finished Goods

Finished goods are items that are done (or finished) with the manufacturing process. Finished goods are typically stored in the warehouse, awaiting shipment to the customer.

IC = Integrated Circuit

An IC is a type of electronic component that is assembled onto an electronics assembly.

ICT = In-circuit Test

An in-circuit test is a test that tests a circuit board to make sure that, to the greatest extent possible, correct components are placed on a circuit board and that they are oriented the correct way. That is, an ICT is basically a parametric test and not a functional one (see FCT above).

Most manufactured circuit boards are functionally tested. Some customers (such as those in the automotive, medical, and aerospace industries) require an EMS to also perform in-circuit testing in addition to function testing. Why is that? The answer is that it is possible for a circuit board to pass functional test with a wrong component on it. This would result in a test escape – a wrongly built circuit board will be shipped to the customer. While a circuit board may function correctly with a wrong part on it, there could be other negative consequences, such as reduced life, or less noise immunity.

Because ICT is an additional manufacturing step that takes time, it adds to the manufacturing costs of an electronics assembly. While it might seem dangerous to not use ICT, an EMS typically has plenty of controls in place to help assure that a circuit board is not manufactured with an incorrect component.

IMDS = International Material Data System

The IMDS was created by the automotive industry to be a tool that records the material composition of items within a vehicle, to help facilitate vehicle disposal.

Electronic contract manufacturing companies that provide circuit boards to automotive customers must submit the chemical composition of their manufactured circuit boards. This typically involves the EMS reaching out to their suppliers and getting the required IMDS info of the supplied components.

IPC = Institute of Printed Circuits

The IPC is a non-profit organization that creates standards for the electronic manufacturing industry. They seek to help manufacturers build better assemblies.

LF = Lead Free

There are 2 main categories of solder: leaded and lead-free. Typically, solder, electrical components, and tools (such as soldering irons) will be marked with “LF” (or “Pb free”) to indicate that the solder or the component does not contain lead. In the case of tools like soldering irons, it means that they are to be used on lead-free components.

MO = Manufacturing Order

Electronics manufacturers maintain a build schedule. This schedule list the various assemblies that they will manufacture. The schedule will contain the assembly part numbers, quantities to be built, and dates the builds will take place. The individual builds are typically assigned unique Manufacturing Order numbers. Some EMS companies refer to these as Job Orders.

MOQ = Minimum Order Quantity

The MOQ represents the minimum amount of components or material that a supplier will sell to a customer.

An EMS company has to purchase their materials from suppliers. These suppliers frequently have minimum order quantities. An EMS company may in turn quote minimum order quantities for circuit boards that they will manufacture for customers.

To learn more about MOQ, check out this article: https://www.abetterlemonadestand.com/what-is-moq-meaning/

MRP = Material Requirements Planning

When someone refers to their “MRP system”, they are referring to a large software package that helps employees run a successful manufacturing business. It does so by helping employees perform these job functions:

  • Entering and tracking of customer orders
  • Budgeting
  • Forecasting
  • Resource planning
  • Inventory management
  • Shipping
  • Receiving
  • and numerous others

Over the years MRP software vendors have increased the functionality of their products, resulting in even more features. The result has been an evolution in the acronym from “MRP” to “ERP”, where the “E” stands for “Enterprise”.

NRE = Non-recurring Engineering

The term “NRE” usually goes with the word “cost” as in “NRE cost”. This cost represents a one-time cost (i.e. a “non-recurring cost”) that an EMS company will charge the customer as a result of starting operations for a customer’s product. You can think of this as a kind of startup cost.

When an EMS company begins operations for a customer’s product, the EMS company will need to obtain things like tooling in order to manufacture a customer’s design. For example, the EMS most certainly will have a solder paste machine. This machine requires a stencil. Normally these stencils are made by an outside machine shop. The EMS company will need to purchase this stencil. The cost of this stencil is usually passed on to the customer in the form of an NRE charge.

PCB = Printed Circuit Board

A printed circuit board is a thin piece of material that electrical components are soldered onto.

PCBA = Printed Circuit Board Assembly

A printed circuit board assembly is a printed circuit board that has components (such as ICs, capacitors, resistors, connectors, etc.) assembled onto it.

PFMEA = Process Failure Mode Effects Analysis

PFMEA is used by EMS companies to see where in their manufacturing process they are susceptible to creating manufacturing defects. When the analysis is complete, they will put measures in place to mitigate the risk of creating defects.

P/N (or PN) = Part number

An EMS company will have all kinds of documents – such as bill of materials and purchase orders – that will contain part numbers. It is common for the various part numbers in these documents to be listed in a tabular format with the column heading being “P/N” or “PN”.

PO = Purchase Order

A purchase order is a document sent by the purchasing company to a supplier that is a request for parts. The document shows the part numbers (and their prices) as well as the expected delivery date for the parts.

PPAP = Production Part Approval Process

Customers from the automotive industry typically require their EMS company to have their production process approved before mass production can take place. This approval process is very detailed, all aspects of the manufacturing process is analyzed because a problem with some seemingly insignificant process could have severe detrimental affects on a finished product – such as a car.

Once PPAP approval is granted, even the slightest change in the process requires customer approval first.

PPM = Parts Per Million

A good EMS company will keep track of their quality defects in terms of PPM. When a company has poor quality, it is easier to refer to their defect rates in terms of percentages. For example, a company with a defect rate of 1% would have 10,000 defects out of 1,000,000 parts. 10,000 out of 1,000,000 equals 10,000 PPM. So, in this case, it is much easier to refer to this company as having a defect rate of 1% than 10,000PPM.

Conversely, it is much easier to use PPM instead of percentages for companies with good quality. For example, a company with a defect rate of 4 PPM, in terms of percentages, would have a defect rate of 4 / 1,000,000 = 0.0004%.

PSW = Part Submission Warrant

This is a form that is issued by a manufacturer to their customer that states and gives evidence that they can meet the customer’s quality requirements as well as other requirements, including delivery dates and throughput.

RFQ = Request for Quotation

A company will ask another company to quote a price for products or services based on certain requirements – such as quantity over a period of time.

RMA = Return Merchandise Authorization

When a company wants to ship back material to a supplier, typically an RMA number is needed. When the supplier grants that a company can ship material back, the supplier will typically give the customer an RMA number along with specific instructions on labeling the return material with the RMA number so that when the supplier’s warehouse receives back the product, they will know what to do with the material.

RoHS = Restriction of Hazardous Substances Directive

A RoHS compliant component is a component that does not have more lead in it than what is acceptable.

SMT = Surface-mount technology

SMT machines are machines that can place electrical components onto the surface of a printed circuit board (PCB). Such machines can place parts at a high rate of speed, resulting in high efficiencies. A much slower way to assemble circuit boards is with humans placing the leads/connections of electrical components through holes on the PCB.

SOP = Start of Production

The term SOP usually goes with a date. For example, “the SOP date is 8/1/2021”. This refers to the date a design officially goes into production. It is kind of a confusing term for newbies because a design could be produced several times before the SOP date. So, why isn’t the earliest of these dates referred to as the SOP date? The answer is that these earlier production dates are prototype builds; the units produced here don’t go into a customer’s product and sold to an end customer; these prototypes are analyzed by technicians and engineers to see if the design is solid and the manufacturing process is smooth and as error-free as can be.

So, the SOP date is really the date when an EMS company will begin manufacturing for a customer and that the customer will officially use these manufactured units in their product.

SPI = Solder Paste Inspection or Serial Peripheral Interface

Depending on who you are talking to, the acronym has different meanings. For Production people, SPI stands for Solder Paste Inspection. For Design Engineers, SPI stands for serial peripheral interface (a type of communication standard like USB, or Bluetooth).

U/M = Unit of Measure

U/M, also called UM or UOM, is short for “unit of measure”.

WIP = Work-In-Progress

The term WIP stands for work-in-progress. In manufacturing, there are 3 main locations where components may reside: 1) as raw components in the warehouse; 2) as completed units (also called “Finished Goods”) in the warehouse; 3) as WIP – which means components that reside on the manufacturing floor that are in a state of being assembled or used in the manufacturing process.