How Much Does It Cost To Get A PCB Assembled?

 In addition to bare board fabrication expenses, stuffing a printed circuit board with components (often termed PCB assembly or PCA) carries its own set of costs driven by factors such as component selections, processing technologies, testing needs, and order quantities. This article examines typical assembly pricing models and what elements influence cost when building populated boards.

PCB Assembly Cost Structure

The total cost quoted by an electronics manufacturing services (EMS) provider or contract assembler generally contains both fixed and variable elements:

Typical PCB Assembly Quote Elements

• NRE Charges
• Tooling & Programming
• Test Fixture Building
• Process Engineering
• Bill of Materials Optimization
• Component Material Costs
• Variable Processing Charges
• Solder Paste Printing
• Pick & Place Machine Setup
• Solder Reflow
• Cleaning
• Inspection & Testing
• Packaging & Handling

The non-recurring expenses (NREs) tied to project initiation represent fixed overhead costs independent of order volume, while the assembly process steps themselves scale in pricing with quantity. Understanding this fundamental divide is key to estimating budgets.

NRE Charges

Upfront NREs include charges for production preparation spanning:

Assembly Programming

Machine data instructions must be coded to guide automated pick-and-place arm movements, component rotations, and sequence priorities tailored to board layouts. Each new board generally requires several hours of dedicated programming for optimal efficiency.

Test Fixture Building

Any fixture hardware needed to interface boards with in-circuit test stations or functional validation equipment to confirm assembly correctness must be custom built for new board designs. Simple clamshell test points may suffice, but complex boards require mating connectors, pogo adapters, isolation buffers, etc.

Tooling Adjustments

Tweaks to factory equipment like stencils, tray holders, panel frames, and other tooling elements impacted by board dimensions often require updates when switching designs. Mechanical, pneumatic, vacuum, and electrostatic adjustments may be necessary. New stencils are common requirements.

Engineering Analysis

Prior to full scale ramp-up, assembler engineering teams analyze schematics, layouts, BOMs, fabrication/assembly documentation, and early prototypes to tailor processes specific for each board product. Potential issues need identification, equipment evaluations are completed, and process qualification builds conducted.

While NRE charges seem high compared to small assembly batches, these expenses get amortized over total production volume, dropping effective overhead costs per board at volume. For complex boards, NREs can easily exceed $10k, while simpler boards may require just a few $k upfront. NRE pricing should be clarified in quotations before proceeding.

Component Costs

The bill of materials (BOM) makeup dictated by board schematics primarily drives total components cost, but contract assemblers can suggest alternate parts with better pricing at volume.

BOM Line Item Pricing

Both material and unit charges per BOM line item factor into pricing. Standard small passives or generic actives can be less than a few cents, while advanced semiconductors, FPGAs, RF chips range over $10–100+ driving overall assembly pricing higher even when ignoring placement or soldering charges.

Reel Quantities

Larger reel component packaging further reduces per part cost but may have higher minimum order quantities (MOQs). If BOM optimization supported, shifting towards reeled components lowers overall materials cost.

Customer Supplied Parts

Rather than having assemblers procure all BOM elements, supplying fixed configurations or high cost parts yourself avoids excessive material markups while guaranteeing authentic components are used. This asset management must be weighed against internal overhead expenses.

Board Complexity Factors

In addition to materials themselves, physical PCB attributes also determine assembly process pricing between loading, soldering, cleaning, inspection etc process steps.

Placement Density

Component packing density set by board layout complexity pushes pick-and-place cycle times higher and risks occasional misseddrops. Higher density may force slower precision machine vision alignment steps during loading as well. Expect pricing premiums above roughly 100 components per square inch depending on part pitches.

Odd Components

Special support tooling for loading small passives like 01005 chips or handling tall connectors adds process considerations or external hand tooling tasks compared to standard 0603/0402 SMT parts, increasing placement pricing.

Double Sided Loading

Needing to stuff components on both top and bottom surfaces requires flipping boards and running through SMT lines twice, driving cost 2x higher compared to single sided placement. Reduce layer count if feasible during design to avoid.

Through Hole Parts

Leaded through hole parts demand separate insertion steps compared to sole SMT loading. While automatable, these extras process steps add cost. Some mixed technology boards may unavoidably require a small number of connectors or pins.

Solder Types

Lead-free SAC alloys are now standard, but some boards still rely on tin-lead solders. Any secondary solder pots or paste printing setups impinge on line changeover and reduce throughput driving cost upwards.

Selective Depanelization

Singulation routers cut assembled panels into individual PCBs. Skipping V-scoring depanelization early on keeps material utilization high but requires manually separating completed boards later when panels hold components. This risks damage without proper fixtures.

Testing and Inspection

Stringent testing protocols guarantee assembly quality but rack up expenses through capital equipment demands and reductions in process parallelization.

Visual AOI

Automated optical inspection (AOI) scanning looks for missing or skewed parts, solder defects, and other assembly flaws using pattern recognition algorithms after reflow stages. Typical 2D inspection suffices for many boards under $0.01 per capture, while more sophisticated 3D AOI costs multiply higher but captures finer defects that impact reliability statistics.

ICT Probing

Rigorous probing of nets validates end-to-end connectivity across all nodes by electrically checking shorts/opens down to component pin resolution. Bed of nails test fixtures required for ICT probing usually exceed $5k in custom tooling costs alone before validation charges tally upwards of $0.05 per net probed, easily eclipsing base assembly charges.

Functional Testing

Exercising critical interfaces or validating proper firmware operation requires development of custom test scripts plus any associated test equipment. Functional test creation itself can run $100 per hour between testbench development, debugging, and documentation for complex parallel testers. Per board functional test execution pricing in smaller volumes then range from $2.50-$25+ impacting small batch pricing dramatically. But this drops to under $0.10 at high volumes with test set amortization.

X-Ray Inspection

X-ray imaging used for BGA/CSP packages and multi-layer boards ensures hidden solder joint or via quality. Typical snapshot inspection costs around $5 per board for standard resolution. Then full multi-angle laminography can run upwards of $50–100 per analysis during new product introduction.

Economies of Scale

Assembly pricing is not strictly linear with ordered quantity due to improved efficiencies from batch processing and equipment utilization at volume production scales. Cost per board drops dramatically above ~500+ units.

Assembly Cost Per Board vs Volume

Order QuantityPrice per BoardAssembly Location1–50 boards$50 — $500+Local CM or Self50–250 boards$10 — $50Southeast Asia250–1,000 boards$5 — $25China1,000–5,000 boards$2 — $15China5,000–25,000 boards< $10China

Capital equipment like pick-and-place machines or reflow ovens cost upwards of $250k. Fully burdening monthly lease financing, maintenance, and depreciation of this machinery over small prototype runs drastically inflates price. But by batching even medium scale volumes, fixed expenses are amortized lowering assembly pricing exponentially. Approaching 25,000+ boards brings further discounts finally flattening around $2.50 per board. Even domestic assembly quotes can compete if volumes exceed 50k monthly boards.

Frequently Asked Questions

What are the main cost drivers?

BOM component costs, density/complexity factors impacting process tooling, degree of testing/inspection validation, and overall order volumes dictate assembly pricing. NRE charges also represent substantial fixed overheads.

What hidden costs might not be obvious?

Seemingly minor custom process steps like selective wave soldering, depanelization, QFN rework, or special storage/handling requirements rack up expenses not always clear from initial pricing guides. Clarify any unusual fabrication notes that carry through to assembly needs.

What quantity minimizes assembly cost?

Amortizing equipment investments and support staffing expenses over total throughput pushes assembled pricing exponentially lower above roughly 500 boards to approach $5 per board at median volumes with circuits of mid complexity. Further scaling keeps reducing unitary pricing down towards $2–3.