Introduction

Printed circuit boards (PCBs) provide the foundation for almost every modern electronic device. Being able to design and fabricate your own PCB opens up exciting possibilities for custom projects and products. While commercial board houses handle large scale PCB production, DIY methods are also available for hackers, makers, and hobbyists. In this guide, we will explore the basic processes and techniques involved in creating homemade PCBs.

PCB Design

The first step is designing the circuit board layout. This involves planning the physical location of components and routing copper traces to connect them electrically. For custom boards, computer-aided design (CAD) software is used to enable precise control over the layout.

Design Software

Many affordable options exist for PCB design software accessible to makers and hobbyists:

• Eagle – Very popular freeware tool with paid premium options. Large component library.
• KiCad – Open source, cross-platform, full featured. Steep learning curve but very powerful.
• EasyEDA – Online editor with basic free version, more advanced paid options.
• Fritzing – Open source software focused on makers, educators, artists. Breadboard style views. Easy to learn.
• Altium CircuitMaker – Free stripped down version of advanced Altium toolset.
• Autodesk Eagle – Free version for students, enthusiasts, and hobbyists.

These programs provide design features like:

• Schematic capture to convert circuit diagrams into PCB layouts.
• Placement of footprints for components and connectors.
• Routing traces on various layers.
• DRC checks for errors and violations.
• 3D visualizations of board and components.
• Generation of manufacturing outputs like Gerber and drill files.

Most formats can import component libraries, connect to simulation tools, and export manufacturing files. Advanced features like high speed design rules, impedance controlled traces, and signal integrity analysis may require paid upgrades or premium software.

Layout Considerations

Key factors to consider when laying out DIY PCB designs:

• Component Placement – Position parts to minimize wire lengths and enable clean routing. Watch out for collisions.
• Trace Routing – Connect nodes with appropriate trace widths. Avoid crossing split planes.
• Grounding – Use ground pours connected by vias to provide low impedance return paths.
• Board Size – Standard sizes like 100mm x 150mm or 100mm x 100mm make fabrication easier.
• Layer Stacks – 2 to 4 layer designs are typical for DIY boards. Minimize crossovers.
• High Speed – Controlled impedance traces, adequate grounding, and shielding requirements.
• Manufacturability – Suitable clearance between traces, holes, and components. Avoid impossible geometries.

Following design rules and leaving adequate tolerances makes home PCB fabrication much more robust.

Board Materials

Creating the physical PCB requires laminating conductive copper traces between insulating substrate layers. The board material choice affects characteristics like cost, rigidity, thermal performance and ease of fabrication.

FR-4

The most common and cost effective material for DIY PCBs is FR-4 fiberglass. It consists of woven fiberglass cloth pre-impregnated with epoxy resin. Sheets are laminated together using heat and pressure to produce a rigid board. The resin used provides electrical isolation and mechanical structure. Bulk FR-4 can be purchased from various suppliers in sheets sized 9 x 12 inches or 12 x 12 inches. 1.6mm (1/16″) is a standard thickness for home boards.

Advantages of FR-4:

• Inexpensive and widely available
• Good mechanical strength
• Easy to drill and process
• Suitable for many hobbyist projects

Limitations of FR-4:

• Only good for speeds under 5GHz, not ideal for RF
• Lower thermal conductivity than metal core boards
• Requires precise heat control during lamination

Alternative Materials

More advanced substrates can also be used by DIYers:

• Rogers – High frequency RF materials with excellent dielectric properties
• Metal core – Copper or aluminum core board for high thermal conductivity
• Ceramics – Aluminum oxide or aluminum nitride for thermal management
• Teflon – PTFE boards combine good RF performance and low loss

However these exotic materials can be challenging or expensive to source in small quantities. They also require special fabrication techniques compared to standard FR-4 processing.

Making Your Own PCB

With the electrical layout completed and board materials on hand, we are ready to create the homemade PCB. This involves several steps:

1. Print Circuit Layout

The PCB artwork can be printed onto a photoresist coated copper laminate using a high resolution printer or photo plotting service. Most CAD tools can export images in a format suitable for printing. Some key elements:

• Print on transparencies for photo resist patterning
• 1200 dpi provides good resolution
• Actual size 1:1 artwork
• Print minimum trace widths defined in layout
• Include drill holes, cutouts, markings
• May need separate layers for top, bottom, etc.

Laser printing or emailing artwork files to a PCB prototyping service provides another convenient option.

2. Prepare Copper Clad

The base substrate is typically an FR-4 or fiberglass copper clad laminate. Rolls or sheets of copper clad can be purchased from a variety of vendors. The copper foil provides the conductive traces after etching. 1oz (1.4mil) foil is common but thinner 0.5oz copper can enable finer trace resolution. Carefully cut the laminate to match the PCB size using a table saw or rotary tool. Deburr edges to prevent injury from sharp copper.

3. Clean and Dry

Ensure copper surfaces are clean and dry before applying photoresist. Use fine sandpaper or emery cloth to scrub off any oils, oxides or grime. Acetone, IPA or other solvent can assist with degreasing. Avoid touching bare copper to prevent recontamination. Dry thoroughly before coating with photoresist.

4. Apply Photoresist

Photosensitive resist coatings transform printed circuit patterns into 3D profiles that can be chemically etched. Common liquid resists are applied by brushing, dipping or spraying. RK Solid Green or similar dry film can be laminated with hot rollers. Apply resist evenly across copper surface. Soft bake to dry if using liquid resist.

5. Expose Artwork

Next, the printed layout is carefully aligned and brought into intimate contact with the resist coated board. Often sandwiched between glass sheets, this “phototool” stack is then exposed to UV light. A suitable exposure unit can be constructed using UV LEDs or fluorescent tubes. The UV radiation changes solubility of the exposed resist regions.

6. Develop

After exposure, the PCB is soaked in chemical developer solution. This washes away either the exposed or unexposed resist areas, depending on positive or negative resist type. What remains is a 3D mold matching the desired circuit pattern protecting underlying copper. Carefully inspect for any signs of under or over development.

7. Etch Copper

With resist patterned, the board is immersed in acid based copper etchant. Common homemade etchants are ferric chloride or ammonium persulfate. Agitate frequently until all unprotected copper is dissolved away, leaving only the desired conductive traces. Dispose of spent etchant properly.

8. Strip Resist

Remaining resist is stripped away using solvents like acetone. This reveals the finished raw PCB with exposed copper traces ready for drilling, plating and component assembly. Any residues can be removed with light abrasives. Visually inspect for complete resist removal.

9. Drill Holes

Accurately aligned holes are critical for assembling components. Small numbers of holes can be manually drilled using a drill press. For mass production, CNC drilling provides precision alignment at high speeds. Deburr holes afterwards. Breakout tabs help prevent tearing copper annular rings.

10. Plating and Finishing

For multilayer boards, electroless processing like ENIG (electroless nickel immersion gold) can deposit uniform plating on traces and in holes for conductivity and solderability. Carefully follow chemical suppliers instructions. Avoid contamination which ruins plating quality.

This sequence of steps converts the PCB design into an actual fabricated board ready for parts to be soldered. While requiring care and practice, home PCB creation puts custom circuit production within reach of DIYers.

Improving Home PCB Results

Here are some tips for getting good, consistent results when fabricating your own boards:

• Use high resolution film prints and fresh chemicals. Old or diluted solutions cause problems.
• Carefully level and adhere artwork to blank copper clad when exposing. Any gaps degrade resolution.
• Start with larger minimum trace/space designs before attempting very fine features.
• Closely follow chemical supplier data sheets for proper mixing, handling, and disposal.
• Use ceramic crockpots for perfect resist heating instead of ovens or hotplates.
• Agitate boards frequently during etching to ensure uniform material removal.
• Let chemicals thoroughly drain off boards before rinsing to prevent contamination.
• Carefully pre-tin component pads with solder before assembly to ensure good wetting.
• Experiment and tweak processes until achieving satisfying results.

Patience and practice will be rewarded with professional looking home etched PCBs. Small flaws like undercut traces or thin spots can often be reworked post-etching.

Advanced Techniques

Beyond basic single sided boards, more complex multi-layer PCBs are possible with the right equipment. These methods require significant specialized infrastructure.

Photolithography

Photoresists and UV light can pattern layers on both sides of a PCB for plated through hole fabrication. This enables higher component density by allowing traces to zig-zag between sides.

Lamination

Individual double sided boards can be aligned and laminated into multilayer stackups under heat and pressure. This “book binding” technique produces high quality impedance controlled boards.

Pin lamination

Pins laminated into the stackup provide electrical connections between inner layers, removing the need to fully plate holes.

Microvias

With precision laser drilling, microvias under 0.15mm enable extremely dense HDI routing between layers.

Soldermask

Liquid soldermask coatings protect copper traces from oxidation and prevent solder bridges during assembly. Usually green or blue tinted.

ENIG / Immersion Tin

Electroless nickel/immersion gold deposits provide excellent solderability while also protecting copper traces from corrosion.

Impedance Control

Careful stackup design, dielectric selection, and trace geometries achieve target controlled impedance signal traces.

While challenging, these methods allow skilled hobbyists to produce multilayer boards at home rivaling commercial PCB quality. Makers can also partner with hackerspaces or DIY communities to pool expertise and equipment for better results.

Outsourcing Complex PCBs

For hobbyists producing just a few boards, the fixed cost of setting up an advanced in-house fabrication process is likely prohibitive. In these cases, it makes more sense to outsource production of complex PCBs by using a professional prototyping service.

Features that are typical candidates for outsourcing include:

• High layer counts and HDI
• Blind and buried vias
• Fine line traces under 5mil
• Flex and rigid-flex boards
• Tight tolerances or impedance control
• Lead times under 1 week
• High volume orders over 100 boards

Shop around to find a PCB manufacturer that provides online quotes tailored to prototype and small batch orders. Many low cost board houses catering to the maker community offer convenient file upload, rapid turnaround, and even inexpensive assembly services. Leverage these providers to add capabilities beyond DIY fabrication limits.

Ideas for Home PCB Projects

Making your own PCBs unlocks options for custom electronics projects:

• Audio amplifiers or guitar pedals
• IoT and sensor nodes
• Battery chargers or power supplies
• Development and breakout boards
• LED lighting fixtures
• Robotics and drone autopilots
• Homebrew radios and transmitters
• Automotive tuning and telemetry
• Wearable devices
• High altitude balloons and experiments
• Creative art and music installations

For simple designs with largish traces and clearances, homebrew PCBs can look and function nearly on par with commercial boards. Polish skills before attempting fine featured layouts.

Complement traditional etching and drilling with creative embellishments:

• Unique board shapes and outlines
• Artistic soldermask designs
• Decorative labels and markings
• Functional copper elements like antennas or heat sinks
• Hand drawn traces or touch ups with conductive ink

Don’t be afraid to experiment and iterate. Scrap boards make great decorations!

Conclusion

Making DIY printed circuit boards is a learnable skill that taps into the joy of hands-on fabrication. With some knowledge of materials, equipment, and processes, hobbyists can produce functional boards from home labs and makerspaces. Start simple to build confidence before working towards more advanced techniques. Outsource fabrication when project requirements exceed current in-house capabilities. Use online design tools paired with professional board houses for easy access to custom PCBs. Perhaps most importantly, embrace an attitude of discovery and have fun!

Frequently Asked Questions

What software is best for designing DIY PCBs?

For hobbyists, Eagle, KiCad and EasyEDA offer a good combination of free use and learning resources. Start with the tool that feels most intuitive to build skills.

Can I make multilayer boards at home?

Two and 4 layer boards are feasible with careful stacking and lamination. High layer counts require more complex alignment and plating equipment best suited to professional shops.

What are the main challenges etching my own PCBs?

Achieving consistent exposures, getting traces to adhere to the substrate, and uniform copper etching tend to be common pitfalls starting out. Patience and experimentation will improve results.

How fine of traces can I etch at home?

With care 8mil traces are achievable, but start with 10mil or 15mil designs first. High resolution laser printing combined with thin 1/2oz copper foils can produce fine 6mil traces.

What are good starter projects for DIY PCBs?

Basic analog circuits like amplifiers, filters or oscillators are great starting points. Avoid complex mixed signal boards or tight tolerance layouts initially. Build confidence first with more forgiving analog designs before tackling dense digital circuits requiring precision.