What is PCB Proto?

PCB Proto refers to prototype printed circuit board (PCB) fabrication and assembly services. PCB prototyping allows engineers and designers to create and test initial versions of their PCB designs before mass production.

Prototyping is a critical step in PCB development. It enables validation of the design, component selection, and manufacturability. Prototypes identify potential issues early on, reducing the risk of costly problems arising during volume production.

PCB prototype services typically offer quick-turn fabrication of small quantities of boards, from just a few up to a few dozen. The prototypes are built to the same specifications as production boards in terms of materials, copper weights, soldermask, silkscreen, surface finish, etc. This ensures the prototypes will closely match the final production boards in form, fit and function.

Many PCB proto services also offer assembly of the fabricated boards. This involves soldering of all the components, from simple passives to complex ICs, to complete a functional board. Prototype assembly is usually done by hand in low volumes, as opposed to mass production which utilizes automated pick-and-place machines and wave/reflow soldering.

Advantages of PCB Prototyping

There are several key benefits to prototyping PCBs before full production:

Design Validation

The primary purpose of a prototype is to validate the PCB design. This includes testing that:

• The schematic design is correct
• Components are properly selected
• Footprints and pinouts are accurate
• Routing is optimized without errors
• Manufacturing specs are set correctly

Prototyping allows hands-on testing of the physical board to confirm everything that worked in CAD software also works in the real world. Any issues found can be debugged and the design revised before moving to production.

Manufacturability Testing

Prototypes also serve to test the manufacturability of the PCB design. Certain design features may turn out to be difficult, unreliable or impossible to manufacture in volume.

For example, the design may call for an impractical trace/space spec, too small of via holes, or an unusual board outline. Fabricating prototypes will identify any such manufacturability problems. The design can then be revised to be more fab-friendly.

Functional Testing

Assembled prototypes allow testing of the complete board functionality. All the components can be powered on and run through test procedures to validate the board does what it’s designed to do. Any bugs or design flaws can be identified and corrected pre-production.

Functional testing may include:

• Power on/off
• Voltage levels
• Signal integrity
• Programmability/firmware
• Mechanical fit and mounting
• Environmental conditions

Thorough prototype testing provides confidence the design is solid and ready for production.

Speed to Market

PCB prototyping accelerates development cycles and reduces time to market. Prototypes can typically be fabricated and assembled in a matter of days, as opposed to weeks for production.

This fast turnaround allows designers to quickly test and revise designs. Problems can be caught early and fixed before they become costly production delays. Validated prototypes enable final products to be brought to market as quickly as possible.

PCB Proto Manufacturing Process

The PCB prototyping process generally follows these steps:

1. Design submission – The customer submits their PCB design files, usually Gerber or ODB++ format, to the prototype service. Specifications like material, copper weight, color, surface finish, etc. are also provided.

2. Design review – The service provider’s engineers review the submitted design files. They check for any missing information, design rule violations, or manufacturability issues. Unclear or problematic issues are clarified with the customer.

3. Quotation – Based on the design complexity and requirements, the service provider gives the customer a price quotation and lead time estimate for the job.

4. Order placement – If the quote is accepted, the customer places the order and provides payment to proceed with manufacturing.

5. Fabrication – The bare circuit boards are fabricated according to the design files and specifications. This involves imaging, etching, drilling, plating and other processes to build up the copper layers and complete the bare board.

6. Assembly (optional) – If assembly is required, the components are then soldered onto the fabricated boards. For prototypes this is typically done manually by skilled technicians. SMT and through-hole components are placed and soldered according to the design.

7. Inspection & Test – The completed prototype boards go through visual inspection and electrical testing as needed. This may include automated optical inspection (AOI), X-ray, flying probe and other tests to verify quality.

8. Shipping – The finished prototypes are packaged and shipped to the customer. Rush shipping options are usually available if needed.

The entire prototyping process can be completed in as little as 24 hours in some cases, although 3-5 days is more typical. The speed depends on the complexity of the design and the service provider’s capabilities.

Choosing a PCB Proto Service

There are hundreds of companies offering PCB Prototyping Services, so selecting the right one is important. Key factors to consider include:

Capabilities

Make sure the service provider can handle your specific PCB Requirements, such as:

• Board size and thickness
• Layer count
• Material (FR-4, Rogers, flex, etc.)
• Copper weight
• Minimum trace/space
• Smallest drill holes
• Surface finish (HASL, ENIG, OSP, etc.)
• Soldermask and silkscreen color options
• Controlled impedance
• Blind/buried vias

The more advanced capabilities a provider offers, the more flexibility you’ll have in your design options. But if your needs are basic, you don’t necessarily need to pay for high-end capabilities.

Speed

How quickly do you need your prototypes? Rapid prototyping services can deliver boards in 24-48 hours, while standard services may take a week or more. Consider your project schedule and look for a provider with turnaround times that meet your needs.

Assembly Services

If you need your prototype boards assembled, look for a provider that offers both PCB fabrication and assembly. This one-stop shopping saves time and money compared to using separate fab and assembly shops.

Also check their assembly capabilities in terms of component types (SMT, BGA, QFN, etc.), placement accuracy, soldering processes, etc. Make sure they can handle the needs of your particular design.

Quality

Prototype PCBs must be high quality in order to properly test and validate the design. The fab and assembly should be done with the same processes, materials and standards as production boards.

Look for certifications like ISO 9001, IPC 600, and UL listing. It’s also wise to get references or reviews from previous customers to gauge their satisfaction with quality.

Service and Support

The level of customer service is important, especially if you’re new to PCB Proto. Look for providers with knowledgeable, responsive support staff that can answer technical questions and keep you updated on job status.

Consider the convenience factors like online quoting and ordering, automated order tracking, and fast shipping options. The overall customer experience should be simple and painless.

Price

Of course, price is always a factor in choosing a prototype service. But beware of “too good to be true” prices that may indicate sub-standard quality or service.

Get quotes from a few different providers to compare. Make sure you understand what’s included and not included in the pricing. Consider the total cost of ownership including shipping, duties, and potential quality issues, not just the per-board price.

PCB Proto Design Tips

To get the best results from PCB prototyping, follow these design tips:

Keep it Simple

Prototypes should be kept as simple as necessary to prove the concept. Don’t include extra features or components that aren’t essential to the core functionality. This reduces complexity, cost and potential for errors.

Use standard materials, sizes and specifications where possible. Avoid pushing the boundaries of manufacturing capabilities in prototypes. The goal is to quickly validate the basic design, not test the limits of PCB fabrication.

Design for Manufacturability

From the start, design your boards with manufacturing in mind. Follow the design rules and guidelines of your chosen fab and assembly shop.

Avoid things like tight trace/space, small vias, odd board shapes, and other features that may be difficult or impossible to manufacture. The fab shop can usually provide a DFM (Design for Manufacturability) check before you submit your final design files.

Allow Space for Debug

Prototypes often require some level of debugging, so design with that in mind. Include test points, probe access, and other features that allow for easy testing and measurement.

Leave some open space on the board for bodge wires or component changes. If the design uses SMT components, consider including a few through-hole pads for critical signals so they can be accessed with probes.

Plan for Revisions

Assume your prototypes will require at least one design revision, and plan accordingly. Don’t order too many boards on the first spin, since some will likely be scrapped.

Use flexible circuit design practices that allow for changes. For example, use modular sub-circuits instead of a single integrated design. This allows sections to be revised without re-spinning the entire board.

Label Clearly

Prototypes can be confusing to keep track of, especially if there are multiple versions or revisions. Clearly label each board with a name, revision number, and date code. This can be done with silkscreen text or a printed label.

Also consider using different soldermask colors for different prototype versions. This makes it easy to tell the boards apart at a glance.

PCB Proto FAQs

How long does PCB prototyping take?

Turnaround time for PCB prototyping can vary from 24 hours to several weeks, depending on the service provider and the complexity of the design. Typical turnaround for standard 2-4 layer boards is 3-5 days.

How much does PCB prototyping cost?

The cost of PCB prototyping depends on the board specifications, quantity, and turnaround time. A basic 2-layer board might cost $30-$50 each in low quantities, while a complex multi-layer board could be several hundred dollars each.

Most service providers have a minimum order cost, regardless of quantity. This is typically around $100-$200.

For accurate pricing, it’s best to get a quote from the specific service provider based on your design files and requirements.

What files are needed for PCB prototyping?

PCB prototype services typically require the following files:

• Gerber files (RS-274X format) for each layer of the board
• NC drill file
• Centroid or pick-and-place file (for assembly)
• Bill of Materials (BOM)
• Any additional drawings or specifications

The service provider will have specific instructions on how to generate and submit the necessary files from your CAD software.

What is the minimum quantity for PCB prototyping?

The minimum order quantity (MOQ) for PCB prototyping is usually just a few boards, often as low as one. This allows designers to get just a few boards made for initial testing.

However, the MOQ may be higher for some service providers or for more complex designs. It’s also common for the per-board price to be lower at higher quantities, so it may be more economical to order a few extras.

Can I get assembled PCB prototypes?

Yes, most PCB prototype services also offer assembly of the fabricated boards. This is typically done by hand for low volumes, using either through-hole or surface mount components.

The level of assembly complexity varies by provider. Simple designs with larger components are easier to assemble than complex boards with fine-pitch SMT parts. Some providers may have limitations on the types of components they can place or the minimum pitch of the pads.

If you need assembled prototypes, it’s best to choose a service provider that offers both fabrication and assembly. This avoids the need to manage two separate suppliers and ensures the fab and assembly processes are well-matched.

Conclusion

PCB prototyping is an essential step in the electronics design process. It allows designers to quickly validate their designs, test for manufacturability, and debug any issues before committing to full production.

There are many PCB prototype service providers available, each with different capabilities, speeds, and costs. To choose the right one, consider your specific design requirements, timeline, budget, and the level of service and support you need.

By following best practices for PCB prototype design, working closely with your chosen service provider, and thoroughly testing your prototypes, you can bring your electronic product to market quickly and with confidence.