PCB Assembly FAQs
PCB assemblies play a pivotal role in the development and production of electronic devices. It takes an expert to connect the conductive channels of a circuit board so that a piece of technology performs as intended. To clarify the work that goes into PCB fabrication, the professionals at Electronic Manufacturing Services Group, Inc. put together a list of frequently asked questions pertaining to this technology.
1. What Is a PCB and What Do They Do?
A printed circuit board (PCB) can be defined as a single or multilayer surface used to mount components of an electronic system. These units help keep delicate components such as capacitors, resistors, diodes and semiconductors organized for transmitting input data from one location to another. Printed circuit boards can take on numerous shapes and sizes to account for the application at hand.
PCB technology exists in virtually all industries using hand-held devices, smartphones, tablets and computers. Incorporating units within consumer products allows for automation and enables mounted components to communicate with one another.
How a PCB Works:
Printed circuit boards hold electrical components in place. Designs may feature fiberglass or a similar laminate material to serve as a home for etched electrical pathways. Copper lines enable charges to move about a PCB layer, powering component sections along the way. You can think of copper etching almost like physical wires where electricity travels in a set direction to power a device.
2. What Are the Different Types of PCBs?
PCB units exist in several forms for diverse applications. Selecting an appropriate build for a product will require an engineer to consider the intended use of a device, its dimensions and its power specifications. Review the following to understand the types of printed circuit boards and which varieties are suitable for your endeavors:
- Single-sided PCBs: PCB fabrication involves making the circuit board out of one layer of substrate and a thin layer of metal. All components are soldered onto a single side.
- Double-sided PCBs: A type of PCB where conductive metal sheets are applied to both sides of a substrate. Holes may be drilled through the center of the circuit board to allow connections to run to both sides.
- Multilayer PCBs: A minimum of three double-layered PCBs stacked on top of one another with several layers of insulation to limit heat transfer. Special adhesive glues keep the series of PCBs together.
- Flexible PCBs: Printed circuit boards showcasing flexible substrates to help engineers adapt to compact product shapes. The technology may exist in the form of single-sided, double-sided or multilayer builds.
- Rigid PCBs: Useful for consumer products that keep the same shape throughout their life span. Rigid PCBs are manufactured using rugged substrates that resist twisting.
- Rigid-flex PCBs: Printed circuit boards using both rigid and flexible materials. These configurations allow product developers to save space, as rigid and flexible connection methods may be included on the same circuit board.
- Aluminum-backed PCBs: A type of PCB that substitutes an aluminum substrate where fiberglass would be. Designed for use with high-power PCB electronics like LED lights.
- High-frequency PCBs: Circuit board engineered to send signals as strong as 2 GHz.
3. What Are Some Common Uses for PCBs?
PCB units are present in technologies used for both work and leisure. Some of the main professional uses of printed circuit boards relate to the automotive, industrial and medical industries.
Climb into any modern vehicle and you're sure to find a handful of flexible PCBs inside the cabin. Automakers look to flexible PCB technology to program entertainment systems, temperature control switches and navigation devices. Integrating a flexible PCB unit into a vehicle is a great way to configure safety features so that they perform when exposed to vibrations and changes in temperature.
Printed circuit boards help reduce the number of human errors in a manufacturing facility due to their automation capabilities. High-powered presses, ramps and pressure readers commonly showcase high-frequency PCBs for demanding applications that call for accuracy.
Medical professionals rely on compact PCB varieties to administer medications, monitor vital signs and diagnose chronic health issues. Rigid-flex PCBs often make their way into pacemakers, X-ray machines, CT scanning systems and other medical-grade equipment due to their reliability. As medical technology continues to shrink in size, the opportunities for printed circuit board installations grow larger.
Other Examples of PCBs in Real Life
You can find dozens of PCB units in home appliances and "smart" installations that connect to phones, laptops and mobile devices. Below are some popular examples of technologies that contain a PCB:
- Coffee makers
- Home thermostats
- Lighting controls
- Powered door locks
- Gaming consoles
4. What Are PCBs Made From?
The PCB fabrication process looks different based on the intended purpose of the unit and how much power is necessary to make an electronic device function. Before selecting the materials for a circuit board assembly, it's a good idea to familiarize yourself with the four main parts of a PCB unit:
- Substrate: The structural frame of the circuit board — all components fasten to this surface.
- Laminates: Materials that hold all PCB layers together.
- Solder mask: Sits on top of copper foils for isolation purposes and shields connections from environmental elements.
- Silkscreen: Fastens to the solder mask so components can be labeled.
Common PCB Materials
No two circuit boards are exactly the same in terms of construction. If you are new to printed circuit board technology, the following list highlights the three most popular materials involved in PCB manufacturing:
- FR-4: A flame- and water-resistant substrate material known as fiberglass. Professionals opt for FR-4 substrates because they offer a high level of tensile strength in lightweight packages.
- PTFE: Teflon laminates for high-speed circuitry. PTFE is associated with high-frequency PCBs for its outstanding flexibility, physical strength and ability to adapt to hot and cold temperatures.
- Copper: Durable metals like copper, aluminum and iron are excellent conductors of electricity. Choosing one of these metals for a circuit board assembly will facilitate a healthy current flow.
5. Can I Update an Old PCB?
Printed circuit board updates are a cost-effective way to make changes to a preexisting electrical system. It takes a skilled individual to complete these jobs with safe and consistent results. One real-world example of why someone would want to implement PCB upgrades is to prepare for an all-new product model that differs from a previous generation.
Utilizing design software is helpful when making adjustments to a PCB. User-friendly software programs make it possible to upload documents to keep track of any changes you may include with future production runs. Working from an existing template can save you from having to start over from scratch.
6. Can PCBs Be Recycled?
Outdated PCBs can be stripped of parts for use in other projects. It is important not to discard old PCBs in the trash to prevent components from ending up in landfills. Instead, engineers can remove and reuse capacitors, resistors, switches, transistors and hardware to cut costs on future endeavors. PCB recycling requires careful disassembly using specialized tools.
Metals like copper should be salvaged whenever possible. Select organizations may collect recyclable sections of circuit boards, which can undergo smelting to become something new.
7. What Are the Sizing Options for PCBs?
Sizing options for printed circuit boards are nearly endless. There is no such thing as a one-size-fits-all PCB solution, so a product's shape, thickness and power requirements will determine what ends up on its circuit board. As a rule of thumb, a product's component layout must not exceed past the edge of the solder pad for assembly.
No industry standard exists for PCB thickness, but most units seen in EMSG's PCB assembly service measure around 0.062 inches thick.
8. How Long Does the PCB Assembly Process Take From Start to Finish?
Electronic Manufacturing Services Group, Inc. operates a 20,000 square-foot facility in York, Pennsylvania, to complete PCB assembly services of 50,000 units or less. We proudly serve our customers with lead times as quick as one to three weeks for your convenience. Here is a breakdown of our PCB assembly service timeline:
- Receive all production components (three to 14 business days)
- Quality inspection (one business day)
- PCB assembly (three business days)
- Shipping (one to two business days)
9. What Are the Steps to Assemble a PCB?
EMSG guides you through each step of the PCB assembly process from beginning to end. We communicate with your company's design team to paint a clear picture of what your printed circuit board orders will look like upon arrival. Once the design is approved by you, we move through the procedures below for project completion:
- Apply solder paste to board: A thin layer of stainless steel is placed where we'll mount the PCB components.
- Component mounting: Surface mount components are soldered in place using automated technology.
- PCB inspection: Our staff performs an X-ray inspection to spot any surface-level defects.
- Functional test: Equipment operators will run signal simulations through the circuit board to ensure proper functionality.
10. What Are Conflict Minerals?
Conflict minerals describe resources that are harvested and sold in locations where human rights violations exist. Workers may be forced into dangerous environments to acquire gold, tungsten and other rare materials to turn profits.
EMSG abides by all guidelines set by the United States Congress. We actively monitor our supply chain and do not work with PCB conflict minerals from areas such as the Democratic Republic of the Congo. You can view our statement on conflict minerals online.
11. What's the Difference Between Through-Hole Mounting and Surface Mounting?
Through-hole mounting configurations date back to the 1980s, when engineers were seeking printed circuit boards that could offer increased reliability in tough environmental conditions. In this setup, leads run from both sides of a PCB via predrilled holes. Fastening leads through openings in the PCB creates strong mechanical bonds for strenuous applications like those in the automotive and aerospace industries.
Surface mounting technology involves placing all electrical components on the surface of a PCB. Surface mounting methods are generally less expensive, as no drilling is required during assembly. These PCB structures are smaller in size and work with higher electrical capacities.
12. How Do You Clean a PCB?
A PCB is susceptible to dirt, dust and corrosion throughout its lifetime. Cleaning your PCBs can prolong the life of your investments when done properly. How you go about cleaning a PCB unit will depend on the condition of the technology, but simple household products are often all you need to restore a circuit board:
- Can of compressed air: Spraying air from a nozzle kicks up dust and contaminants trapped within vents.
- Isopropyl alcohol: Look for products containing 90% alcohol or more for desirable results. Spread the fluid lightly across the PCB surfaces using a lint-free cloth, gloves and protective eyewear. Allow the PCB to dry completely before reassembly.
13. How Long Do Assembled PCBs Last?
It's impossible to predict the life span of an entire PCB unit, but conducting periodic visual inspections of PCBs can help you determine if replacement components are in order.
How do you tell if a PCB is bad? Note some of the most prevalent reasons for PCB failure:
- Component burnout: If a product can't power on, open the enclosure and look for melted components.
- Poor storage techniques: Environmental conditions that are overly hot, cold or damp can cause warping or rust, which calls for immediate attention.
14. How Is the PCB Assembly Price Determined?
Representatives at EMSG are happy to provide you with advice on how to keep custom PCB projects within budget. The main factors that affect the price of PCB assembly services include:
- Circuit board size and number of layers: The larger the printed circuit board, the more materials necessary to create the unit.
- Mounting technology: Through-hole PCB units take longer to assemble due to the need for physical labor.
- Order lead times: EMSG can expedite your orders for an additional fee. You can save money by planning out your PCB assembly needs as far in advance as possible.
- Order quantity: It's cost-effective to place orders all at once versus smaller batches throughout the year.
Contact EMSG for PCB Assembly Services
EMSG is based out of York, Pennsylvania, and we serve clients within a 500-mile radius of our facility with precision small-batch PCB assembly services. If you still have questions about our service capabilities, complete a contact form online to get in touch with us today.