Many engineers associate online printed circuit board (PCB) ordering with simple prototype boards and low-volume production. However, Epec’s online ordering tool can also support advanced printed circuit boards, including designs with up to 16 layers, high-temperature materials, blind and buried vias, and controlled impedance requirements.
As online PCB procurement becomes more common, it is important to understand how your circuit boards will be manufactured and whether your supplier can support the technical requirements of your design. Not every PCB manufacturer has the equipment, processes, or expertise needed for higher-complexity boards. Cost alone should not determine supplier selection when quality, reliability, and manufacturability are critical.
A successful PCB order depends on preparation, complete documentation, and a clear understanding of the design attributes that drive manufacturing complexity.
Plan Ahead Before Placing Your Order
One of the most important factors in PCB procurement is timing. Waiting until the last minute can create avoidable schedule risk, particularly when production and transportation challenges affect delivery timelines.
Online ordering systems can simplify procurement, but successful execution still depends on providing accurate manufacturing data and allowing sufficient time for production and shipment. Early planning helps reduce delays and gives engineering and manufacturing teams time to resolve issues before fabrication begins.
For designs ordered through InstantPCBQuote™, every job receives a full DFM review. Potential manufacturability concerns can be identified and addressed before production starts, helping prevent delays caused by incomplete or incorrect design data.
Even relatively complex circuit boards, such as 12-layer PCBs without blind or buried vias, are routinely processed through the online ordering system.
A Complete Data Package Reduces Manufacturing Delays
The quality of the design package directly affects how smoothly a PCB moves from quote to production and ultimately to delivery.
Customers may provide data in many different formats and levels of completeness. A thorough and accurate data set helps prevent engineering questions, manufacturing delays, and unnecessary revisions.
Copper Layer Data
All individual copper layers, including circuitry and ground planes, should be supplied in either positive or negative format.
The preferred data format is RS274X because it can be easily imported into most CAD systems without requiring manual aperture input.
PCB Outline
Provide a full-scale, 1-to-1 outline of the PCB profile.
Manufacturing uses the board outline for:
- Data setup
- Drilling programs
- Routing programs
- Scoring details when required
Accurate outline information helps ensure proper fabrication and panel processing.
Hole Information
Supply a drill program in Excellon format and specify the desired finished hole sizes.
Include a drill chart whenever possible showing:
- Finished hole size
- Plated-through or non-plated status
- Quantity of each hole type
- Required tolerance
Standard manufacturing tolerances are:
- Plated holes: ±0.003"
- Non-plated holes: ±0.002"
Production will determine the actual drill sizes needed to achieve the specified finished hole dimensions.
Soldermask Requirements
Provide soldermask data for both sides of the PCB and specify the required color.
Green remains the most used soldermask color and is widely available throughout the industry. Alternative colors may be available, although offerings vary among manufacturers.
When special soldermask sizing requirements exist, they should be clearly documented.
PCB designers should also consider spacing limitations. Colors other than green can introduce processing challenges when copper-to-copper spacing falls below 0.009" due to differences in pigments and associated chemistries used during finishing and soldermask application.
Silkscreen Requirements
For silkscreen legends, specify the desired color and maintain minimum feature sizes that support reliable reproduction.
Recommended minimum character dimensions are:
- Character width: 0.005"
- Character height: 0.035"
Text smaller than these dimensions may not reproduce consistently during standard processing.
Fabrication Drawing Requirements
A complete fabrication drawing should include:
- Dimensioned board outline
- Defined tolerances
- Finished hole sizes
- Hole tolerances
- Plated or non-plated hole identification
Fabrication notes should also provide important construction information, including:
- Internal layer copper weight
- External layer copper weight
- Applicable specifications
- RoHS requirements
- Product class requirements
Identifying copper weights as finished values provides manufacturing with clear fabrication targets.
Class II and Class III are commonly specified for PCB manufacturing. Class II generally follows standard processing requirements, while Class III typically requires specialized processing, additional cost, and enhanced documentation. Because not all facilities support Class III production, manufacturers should be evaluated accordingly.
What Makes a PCB High Technology?
There is no single definition of a high-technology PCB. Instead, multiple design characteristics can increase manufacturing difficulty and move a board beyond standard processing requirements.
Typical examples include:
- Blind vias
- Buried vias
- Via-in-pad designs
- Layer counts from approximately 8 to 16 layers
- Line widths below 0.005"
- Hole sizes below 0.008"
- Copper weights greater than 4 oz
- PCB thicknesses greater than 0.125"
The combination of these factors determines overall manufacturing complexity.
How Copper Weight Affects Manufacturability
Copper weight can significantly influence trace and spacing capabilities.
For example, a 0.005" trace and 0.005" space design can be processed relatively easily on 1/2 oz copper. When the same design is produced using 1 oz copper, manufacturing becomes more challenging because the copper thickness increases substantially.
As copper thickness increases, tighter trace and space geometries become more difficult to reproduce consistently. Designs using heavier copper often require additional spacing and manufacturing accommodations to maintain acceptable yields.
Why Higher Layer Counts Increase Complexity
PCBs with six to 16 layers are generally considered higher-layer-count designs and often require more advanced manufacturing processes.
As layer counts increase, so does the complexity of fabrication. Many of these designs incorporate blind and buried vias, which require multiple drilling, plating, and lamination operations.
Each blind or buried via structure must be processed within its specific portion of the layer stack. Additional lamination cycles increase manufacturing time, cost, production risk, and the potential for scrap. These factors can also extend overall lead times.
Special Processing Considerations
Castellated Holes
Castellated holes are drilled along the edge of a PCB, leaving half of the hole within the board and half exposed along the routed edge.
These features require:
- Precise drilling
- Plating
- Specialized routing processes
The routing operation must be carefully controlled to avoid damaging the plated barrel. Since castellated features are often critical for subsequent assembly operations, special handling is required throughout fabrication. While some lifting, curling, or burring may occur, careful processing helps minimize these effects.
Specialized Stack-Ups and Dielectrics
PCB thickness requirements and specialized stack-up configurations can complicate production planning.
Specific dielectric requirements may limit material options and affect availability. In some cases, required material thicknesses or copper weights may not be stocked and could require minimum material purchases.
Because online PCB ordering is often associated with lower-volume quantities, sourcing specialized materials can create additional scheduling and procurement challenges.
Soldermask Spacing Constraints
Soldermask protects exposed copper surfaces, helps prevent oxidation, and reduces the risk of shorts during assembly.
For proper adhesion, soldermask typically requires:
- Greater than 0.004" spacing to adhere to laminate surfaces
- Greater than 0.003" relief from copper surfaces
A total copper-to-copper spacing of approximately 0.009" is considered optimal for processing. Spacing below 0.009" becomes increasingly difficult to manufacture, with 0.008" generally representing the lower end of typical processing capability.
Work With Your PCB Supplier on Recurring Design Requirements
Organizations that regularly use the same advanced PCB features can benefit from discussing those requirements with their manufacturing partner.
Recurring design attributes such as specific blind-via structures, layer-stack configurations, or other specialized requirements may affect pricing and manufacturing planning. Addressing these factors in advance can simplify future quoting and ordering activities while reducing the likelihood of unexpected issues.
For customers using InstantPCBQuote™, customized pricing programs can be configured to reflect recurring design characteristics and support streamlined ordering.
Summary
Ordering high-technology PCBs online does not need to be limited to simple prototype designs. Success depends on selecting a capable manufacturing partner, submitting a complete and accurate data set, and understanding the design attributes that influence manufacturability.
Layer count, via structures, copper weight, dielectric requirements, soldermask constraints, and specialized fabrication features all affect production complexity. By planning ahead, providing complete manufacturing documentation, and working closely with a qualified supplier, engineering teams can improve the likelihood of receiving high-quality PCBs on schedule and with fewer production issues.
Key Takeaways
- Order Early to Avoid Delays: Time is the most critical factor when ordering PCBs online. Even with systems like InstantPCBQuote™, shipping and production logistics can still be affected by global transportation challenges.
- Provide a Complete and Accurate Data Set: Submitting detailed fabrication drawings, drill files, outlines, solder mask details, and copper weights ensures a smooth transition from quote to production without costly or time-consuming revisions.
- Know What Qualifies as High-Tech: High-technology PCBs often include blind or buried vias, high layer counts, tight trace and space tolerances, heavy copper weights, or special dielectric requirements, all of which increase complexity and processing time.
- Communicate with Your Supplier: For specialized designs, discuss your recurring design attributes with your online PCB supplier so they can adjust programs, pricing, and manufacturing processes specifically for your needs.
- Choose a Trusted Manufacturer: Partnering with an experienced PCB supplier that offers full DFM review, advanced capabilities, and a reliable supply chain minimizes risks and ensures consistent quality for high-tech online PCB orders.
