PCB Testing

The Importance of PCB Testing & Multiple PCB Test Strategies

Even the most assiduous printed circuit board (PCB) production process can create defects, faults, errors, and other problems. Many PCBs need robust testing early, and often. The proper PCB testing procedure can help accomplish that goal and do a lot more for your PCB production and product lead-time.

 

The Importance of PCB Testing

Testing is a vital part of PCB assembly. Without proper testing, an entire printed circuit board lot can come to you flawed in more than one way. Having your product fail in the field is the wrong time to find out your PCB board has flaws.

However, you also don’t want testing to slow down the production process unnecessarily. You also don’t want testing to occur so late in the process the results turn the whole production lot into a waste of time and effort.

 

 

 

 

Multiple PCB Test Strategies

No single PCB testing system will meet the requirements of every manufacturing environment. Many factors should be taken into consideration when developing a PCB testing strategy. It is essential to focus on the proper test procedure for a particular product, financial scenario, and reliability perspective.

The first step towards building any PCB testing strategy foundation is first to get a good understanding of the types of printed circuit board testing that can be utilized and which PCB testing types are most appropriate for the product’s lifecycle stage. There are multiple approaches to addressing PCB testing and design to optimize the assembly process.

 

In-Circuit Test (ICT)

Many PCB manufacturers prefer to employ one type of in-circuit testing (ICT) or another. Using ICT, a manufacturer can efficiently test individual components and their electronic characteristics.

Traditional ICT requires a “bed of nails” fixture. These fixtures must go through a design phase to fit the circuit board. The fixtures typically come at great expense. ICT shines best when used for end-of-line testing of mostly stable, high volume productions. When the production doesn’t justify the cost, manufacturers must sometimes pass some of the fixture costs on to customers.

 

Fixtureless In-Circuit Test (FICT) / Flying Probe Test

A flying probe test, also known as fixtureless in-circuit testing (FICT), is another type of ICT. Flying probe eliminates the need for custom fixtures, which eliminates added fixture costs. FICT uses test pins that move based on programming (flying probes).

A flying probe test checks for the same things as traditional ICT, but has the advantage of costing less and the ability to test both sides of a PCB. If a defect or problem shows up, the FICT system only requires reprogramming to produce a new piece without the defect. By contrast, and ICT can require an entirely new fixture.

Programming guides the flying probes, which makes it possible to run tests that pinpoint highly specific areas and nodes. That level of accuracy works well with smaller boards and boards with high-density components.

 

Functional Circuit Test

Functional tests are executed to certify that the circuitry functions according to design specifications. Testing is typically performed using DUT (device under test) connectors or a BON (bed of nails) fixture. A pogo pin device, a setup used to establish a temporary connection between two printed circuit boards, is utilized to conduct testing. The number of pogo pins, usually needed for a functional test fixture is significantly less than an ICT fixture.

 

Boundary Scan Testing

The boundary scan is a method for testing wire lines on printed circuit boards. Boundary scan is also widely used as a debugging method to watch integrated circuit pin states, measure voltage, or analyze sub-blocks inside an integrated circuit.

 

Design for Manufacturing (DFM)

DFM is the process of arranging a PCB layout topology to mitigate problems that could potentially arise during the PCB fabrication and PCB assembly processes required to manufacture the electronic system.

 

Design for Assembly (DFA)

The goal of design for assembly is to determine how to design a product such that assembly occurs most cost-effectively. Design for assembly (DFA) is concerned with a reduction of material inputs, capital overhead costs, and reduction of labor. There is a focus on the application of standards to reduce production costs and to shorten the product development cycle time.

 

Design for Test (DFT)

The cost of testing a completed printed circuit board can amount to as much as 30% of the total cost of the product. By designing a product optimized for test coverage and the ability to isolate faults quickly for both PCB manufacturing errors and component failures, design-for-test (DFT) becomes very meaningful to design for profitability.

 

Design for Supply Chain (DSC)

When designing new products, the complexity of supporting long product life cycles containing components nearing the end of life or at risk of becoming obsolete should be a consideration. Stock availability and alternate sourcing are some of the variables an experienced electronics contract manufacturer will consider when setting up a customer’s supply chain for raw materials.

 

Bypassing PCB Testing

Depending upon your scenario, you may not require PCB testing at all. If a product is at a mature point in its lifecycle, a printed circuit board may only need minimal debug and test.

 

 

 

 

 

electronic contract manufacturing

How To Select An Electronic Contract Manufacturing Partner

Strategic outsourcing has become a useful technique for companies across many different industries. OEMs and electronic part manufacturers have not been left behind in outsourcing the production of critical components of their electronic devices. Indeed, electronic contract manufacturing (ECM) partners are integral during circuit board production, assembly, and even during PCB designs.

A productive partnership can result in reduced production costs, reduced lead-time for essential components, increased product quality, and more innovative final products for the marketplace. The most significant challenge that electronic part manufacturers face is selecting the right contract manufacturing partnership.

Finding the right electronic contract manufacturing partner is a process that involves examining your own businesses’ core competencies, as well as how the methods of an electronic manufacturing partner align with your current operations. Here are important factors to consider when selecting an ECM partner.

 

 

1. Analyze your business to determine core competencies

Every business has its unique requirements regarding electronic assembly manufacturing. When looking for a partner, the first thing you should do is to determine the core competencies of your business. Analyze what you can do well, such as which specific parts you can manufacture at high quality but with reduced cost.  Analyze what your company can do well, such as product design, marketing, sales, and product fulfillment.

Next, determine processes that would be better for your business to outsource to minimize costs without compromising on product quality. By evaluating specific product lines and functions to outsource, you can get a clear picture of the kind of electronic contract manufacturing partner you will need. You will also be able to eliminate any potential redundancies in the processes that you seek to outsource.

 

2. How well does the ECM fit with your business?

You will find that every ECM partner is different. The key to selecting the best available partner is to determine how well their processes fit with yours. Analyze how they handle their core production processes, including individual product lines and assemblies. For example, if looking to outsource a specific aspect of an electronic product, do they leverage processes that are compatible with yours? Will your outsourced processes seamlessly integrate with their current capabilities?

You should also analyze the ECM’s customer base. Manufacturing partners should have experience producing components within your industry. These similarities are a sign that your interests are aligned.

 

3. Physically visit short-listed candidates to determine capabilities

When you have shortlisted a few electronic contract manufacturing candidates, you can only know for sure if they will be good partners by carefully observing their operations. It is a good idea to physically visit a few locations and get to see how they run their processes. In particular, carefully observe their electronic contract manufacturing processes that you wish to outsource, such as printed circuit assembly or complete box builds.

Also, determine the financial stability of the partner company to ensure that risks are mitigated moving forward. For example, an ECM company should have enough capital to purchase electric components in advance, even before they can receive payment. This level of financial stability can help reduce lead times and facilitate a smoother manufacturing process.

 

4. Consider references of each electronic contract manufacturer

References always offer valuable insights into the capabilities of electronic contract manufacturing partners. Indeed, previous customers from past partnerships can speak to the working relationship between the company and the ECM.

In particular, seek for references from companies that outsourced similar processes to yours. Outsourcing electronic part assembly is a detailed and delicate process that has minimal margin for error. If a partner has worked with other companies and delivered quality results, this can serve as a mark of confidence for you moving forward.

Also, inquire about customer experiences in areas such as communication and certification. Is the ECM partner willing to discuss their processes in detail? Are they open to disclosing the results of their performance? The contract manufacturer should work with you to develop a partnership, not merely a supplier-customer relationship.

 

5. Onshore or offshore?

At one time, many electronic OEM’s believed it was necessary to move their production processing to offshore destinations because they provided cheaper labor than the United States. Given the changes in global business, the prospect of offshoring, re-shoring, or keeping your business in the U.S. calls for more meaningful evaluation.

Calculating the total cost of ownership will help you determine where the production of your electronic product is best suited. You should first begin with a cost-benefit comparison for each location, considering accurate calculations for:

  1. transportation
  2. currency conversion
  3. labor
  4. the security of your intellectual property
  5. product quality
  6. compatibility of multiple parts
  7. schedule flexibility
  8. distribution to (where the customers are / the product’s final destination)

In most cases, more mature products that require a higher level of manual labor and fewer engineering changes may be better suited for offshore outsourcing. Still, it is crucial to evaluate issues such as the compatibility between your business-and-the electronic contract manufacturing partner must. It is vital that there is alignment between the client and the electronic contract manufacturing vendor regarding your business goals-and-objectives.

PCB Basics Printed Circuit Board

PCB Basics – Getting Started With Printed Circuit Boards

Electronic manufacturing services (EMS) are essential when you are looking to outsource electronic components. Outsourcing parts for assembling is a common manufacturing practice. The process of outsourcing gives your company the chance to get the best components from experienced companies for your products. Printed circuit boards (PCB) are components that act as pathways to transfer electricity in electronic devices. They facilitate a smooth transfer of electricity for the devices to work most efficiently. Printed circuit boards that are manufactured with top-notch technology operate with unparalleled accuracy and precision.

 

Assembling PCBs

PCB assembly is the process of connecting the wiring in an electronic device to the printed circuit board. The process is delicate, and it requires the most care. When the wires are connected to the printed circuit board poorly, the device will not work. When the assembly of the PCB is done right, the device should operate correctly. The PCB is typically the last component in the assembly of electronic devices.

 

Methods for PCB assembly

 

1. Electromechanical assembly

Also known as box-build assembly. It merely uses wires, molded plastic, looms, and other small assembly accessories to assemble electrical devices to the PCB.

 

2. Plated through-hole technology

This method is easy to use because the components of the devices have leads that are attached to the PCB. It is merely a matter of matching the leads to the right locations of the PCB.

 

3. Surface mount assembly

This method offers one advantage of soldiering metal tabs on both sides of the PCB. The quality of soldiering is important to ensure the effectiveness of the device.

 

Finding an EMS partner

Outsourcing is a big decision for a company. When the process is done right, your company can reduce manufacturing cost, delivery time and increase product quality. Here are a few factors to consider when looking for an EMS partner.

 

1. The specifications of the product

Before outsourcing a product for your company, you need to specify what exactly you want. The product should be a perfect fit for your company needs. The quality of the PCBs affects the quality of your final product. The specifications should include the material used, measurements and the purpose. Do not leave any details to chance.

 

2. Select potential suppliers

Research companies that make PCBs that meet your specifications and company needs. Shortlist the companies that have products similar to your needs and the expertise. Make arrangements to do a ground visit to your shortlisted companies.

 

3. The ground visit

The purpose of the ground visit is to get a better understanding of your potential suppliers. It is an opportunity to assess the supplier regarding capacity, efficiency, customer service and how compatible the supplier is to your company. Prepare a list of questions to collect information about the supplier. Some of the critical information includes the supplier’s contact person, delivery, the products they offer, the cost of the product and any other relevant information. Write notes to compare what each potential supplier is offering.

 

4. Request for quotations

When you ask for a quotation, your potential supplier has to consider your product needs and calculate the cost. A quote is essential to determine if the cost is suitable for your budgeted amount. It also gives you a chance to compare various supplier prices and choose the most suitable supplier.

 

 

5. Testing

Before sealing a deal with a supplier, you need to test the process. Request for a batch of the PCBs and see if they meet your standards. Give the supplier a probation period to see how things go. Ensure that the PCBs work on your products. When you approve of the level of service, you can finalize the deal.

The decision to outsource PCBs for your company should not be based solely on the price. The best supplier will help your company boost production volumes, increase the quality of the products and in the end increase your bottom line margins. The market for electronic devices has grown remarkably in the last few years. A significant number of those devices require a printed circuit board. Outsourcing high-quality PCBs for your products may be the x-factor that will help you increase your market share and sales.

box build assembly

What is included in a Box Build assembly?

 

What is Box Build Assembly?

A box build includes all the other assembly work involved in an electromechanical assembly, other than the production of the printed circuit board. A box build is also sometimes called, “systems integration.”

 

The Box Build Process

The box build process is specific to each project and can include varying degrees of complexity at each step. For example, one step may include simply placing a printed circuit board assembly (PCBA) within an enclosure. A subsequent step may include the complex task of connecting a PCBA to a user interface display.

The most common box build assembly processes include installation of sub-assemblies, installation of other components, routing of cabling or wire harnesses, and fabrication of enclosures.

 

 

 

Common Box Build Assembly Services

The following is a list of common box build assembly services a Electronic Manufacturing Services (EMS) provider can provide:

  • system level assembly
  • product assembly
  • sub-level product assembly
  • packaging
  • labeling
  • testing
  • software installation
  • product configuration
  • warehousing
  • order fulfillment
  • after-market service
  • repair

Providing the electronics contract manufacturer with all of the detail involved in a complete product assembly can help them model a box build assembly process to best serve the customer.

 

6 Ways To Shorten The Box Build Assembly Process

The following items are important pieces of information to provide a Electronic Manufacturing Services (EMS) provider. The information contained here can shorten box build assembly time lines and provide for a higher quality electromechanical assembly.

Product Dimensions

Dimensions of the unit include detail on size and weight of the assembly. This detail gives the EMS the necessary information to make decisions about how the units will be handled throughout the complete box build assembly process. Storage, transportation, packaging, and shipping are all processes that are influenced by dimension information.

Bill of Materials (BOM)

The bill of materials is arguably the most important piece of information supplied to a Electronic Manufacturing Services (EMS) provider. It is known as the formula, recipe, or ingredients list. The BOM helps the EMS understand all of the key components and materials that need to be sourced and what will be provided directly by the client.

Every item on a bill of materials has a specific purpose, procurement process, and associated cost. The BOM should have details with respect to item number, reference designator, part description, quantity, manufacturer name, manufacturer part number, package, part type, etc.

A well-crafted bill of materials can help the Electronic Manufacturing Services (EMS) provider anticipate production delays and establish alternative plans for the box build.

3D CAD Model

A visualization of the final product is incredibly important to the box build process. A 3D CAD (three-dimensional computer-aided design) model can provide such a visualization. Software packages for 3D CAD design are commonplace amongst electronics contract manufacturers. These 3D CAD tools can also convert computerized drawings into build instructions that can shorten the complete box build process.

Sample Unit / Prototype

A completed product assembly can be an important physical tool to plan the box build, especially when other sources of information are unavailable. An EMS can often take a customer’s rough prototype and quickly manufacture multiple equivalent assemblies. A highly skilled electromechanical assembly team can often replicate a complete box build with minimal documentation beyond the sample prototype unit provided by the customer.

Testing Use Cases

A customer should identify which tests need to be performed during box build assembly. Use cases for testing can include visual inspection, factory acceptance testing, and specific functional tests.

With any electrical device, safety is a major consideration. Basic testing of electrical systems include the earth bond test and the flash test. An experienced EMS will provide guidance on the types of testing that should be performed during the box build to optimize production time and provide a safe electromechanical assembly.

Packaging and Shipping Info

Outlining how the final box build assembly will be packaged and shipped before the production process begins can provide important planning information to the electronics manufacturer. This detail allows the EMS to make decisions about how the units will managed throughout the complete box build assembly process to optimize box build speed.

 

Starting A Box Build

Both complex and simple box build assembly depends upon thorough requirements gathering. The more information on hand to discuss with the electronics manufacturer during the planning phase can result in a faster, higher quality, and safer product. Versa Electronics is dedicated to developing customized box build processes unique to the objectives of each customer. Versa utilizes lean manufacturing techniques in all operations and processes to realize the best electronic box assemblies in the United States.

Printed Circuit Assembly Documentation

A Quick Guide To Printed Circuit Assembly Documentation

The number of electronic devices that require printed circuit boards is increasing at an exponential rate. User demand, increased functionality, and decreasing device size are driving a surge in demand for printed circuit boards. The global printed circuit board market is expected to reach an estimated $72.6 billion by 2022. To meet increased demand for electronic devices, electronics manufacturers have advanced their technology, their material, and their process to manufacture the printed circuit assembly quickly and more efficiently.

 

 

Regardless of the advanced capability of electronic manufacturing service providers, nearly every electronic device will require functional components to manage power, input/output interfaces, and processing. A printed circuit assembly (PCA) is the result of a process to connect these functional electronic components with the wirings of printed circuit boards (PCB). Before these electronic components can be manufactured, standard documentation for a printed circuit assembly must be created.

This article is a guide to printed circuit board assembly documentation that results in a reliable, repeatable, and cost-effective PCA design.

 

PCA Design Assumptions

For the purposes of this article, we have assumed that the electronic product design and electronic device schematics are validated for purpose and functionality.

 

PCA Bill of Materials

While the electronic device schematics are being developed, a product designer will simultaneously develop the bill of material (BOM). The BOM is a listing of the specific electronic components needed to complete the entire printed circuit assembly. Important data recorded on the BOM includes:

  • Voltage values
  • Values for current
  • Tolerance values
  • Base part numbers
  • Individual part reference designator(s)
  • Quantity
  • Footprint
  • Packaging

 

PCA Approved Vendor List

While the electronic device schematics and bill of materials are being developed, an electronic product designer will also develop the approved vendor list (AVL). The AVL adds more detail to the bill of materials by specifying an exact manufacturer and manufacturer’s part number for each electronic component line item on the bill of material.

Whether a component is single-source or has multiple sources of supply is a critical consideration. An electronic product designer should make every effort to qualify alternate vendors on the AVL as early as possible. There can be notable repercussions to product cost and delivery if a single electronic component has limited sources or is not available to the electronic manufacturer when needed.

 

Printed Circuit Assembly Schematic
A sample printed circuit assembly (PCA) schematic

 

Printed Circuit Assembly Manufacturing Cost & Lead Time

From a manufacturing perspective, the BOM and AVL will involve a high-level of cost and lead-time with respect to purchase and availability at PCA prototype, PCA production, and late-product lifecycle stages. It’s important that the electronic product designer considers electronic material cost, lead-time, and expected longevity for each electronic component defined in the PCA schematic capture and during the development of the PCA bill of material.

 

Printed Circuit Board

A printed circuit board (PCB) is a primary part on the BOM. The PCB is the “canvas” or substrate that provides electrical connection and mechanical support of all the other components on the printed circuit assembly. The printed circuit board is a custom fabricated part critical to the performance of the circuit.

The design of printed circuit board and printed circuit assembly is part art and part science. Component placement with a PCA requires much detail and considerations must include:

  • Effective electrical connections
  • Signal management
  • Thermal effects on the component and complete assembly
  • Part and connection pad placement for assembly efficiency
  • Part and connection pad placement for test and repair
  • Electromechanical consequence for input/output connections
  • Mounting the PCA into an upper level device

 

PCB Design and PCB Testing

Training, experience, and automated software suites are important tools for the PCB designer. The process of taking the schematic, BOM, and AVL through the PCB layout process to a finished physical state requires testing and validation. Software that guides a designer and utilizing “Design Rule Checking” software functions help contribute to a quality base circuit, reduced manufacturing cycle times, and improved electronic product quality and reliability. An experienced PCB designer along with PCB software can ultimately provide a more cost effective and repeatable production assembly.

 

Printed Circuit Assembly Document Package

Once complete the designer will provide a printed circuit board assembly document package to the assembly team at the electronic manufacturing service provider. A comprehensive printed circuit assembly document package typically includes the following:

  1. Bill of Materials (BOM)
  2. Approved Vendor List (AVL)
  3. PCB Gerber data (All layers, Drill files, Aperture files)
  4. CAD data (ODB++ for example)
  5. Centroid file
  6. PCB schematic(s)
  7. PCB fabrication drawing and notes
  8. Assembly drawing(s)
  9. Test specifications (ICT, Functional, ESS, Hi-Pot, etc.)
  10. Quality specifications
  11. Regulatory (UL, TUV, etc.) requirements

While it is possible for a PCA assembly team to quote and build a printed circuit assembly with an abbreviated version of this PCA documentation package, it is not recommended. Detailed documentation for the printed circuit board and printed circuit assembly means a lower probability that an error can pass from the design to the final product.  Troubleshooting is also less complicated when the PCA documentation and PCA physical state becomes comparable “side by side”.

 

BOM for PCA
Sample bill of material (BOM) for printed circuit assembly

 

Summary

The successful launch of a new electronic device is often contingent on the PCA documentation. To ensure the highest quality, timely production, and a cost-effective assembly, it is in the best interest of a PCA designer to complete a thorough documentation package for a printed circuit assembly.