// Complete Electronics Manufacturing Services

Our Services

From rapid prototyping to full-scale mass production, we deliver precision-engineered PCB assembly solutions.

Surface Mount Technology (SMT)

High-speed, precision automated pick-and-place assembly for high-density, complex PCB designs. Handling components down to 01005 footprint.

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Through-Hole Technology (THT)

Reliable wave soldering and manual insertion for heavy-duty components, power electronics, and legacy industrial hardware.

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Turnkey PCBA Manufacturing

End-to-end solutions: IC component sourcing, bare board fabrication, assembly, and final testing. We manage the entire supply chain.

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BGA Assembly

Expert Ball Grid Array assembly with X-ray inspection for high-pin-count ICs requiring precision thermal profiling and placement accuracy.

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Flex & Rigid-Flex Assembly

Specialized assembly for flexible and rigid-flex circuit boards used in aerospace, medical devices, and wearable electronics.

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Prototyping & Testing

Rapid assembly runs for engineering validation, followed by AOI, X-Ray verification, ICT, and functional testing.

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// 01

SMT Assembly Process

Surface Mount Technology (SMT) is the dominant method for populating printed circuit boards in modern electronics manufacturing. Unlike through-hole technology where component leads are inserted into drilled holes, SMT components (known as Surface Mount Devices or SMDs) are soldered directly onto the surface of the PCB. This enables dramatically higher component density, smaller board sizes, and faster automated assembly.

At SMTWISE Technology, our SMT assembly lines are equipped with state-of-the-art high-speed pick-and-place machines capable of placing components as small as 01005 (0.4mm x 0.2mm) with exceptional accuracy. Our multi-zone reflow ovens ensure optimal thermal profiling for lead-free and leaded solder processes.

How Our SMT Assembly Process Works

  • Solder Paste Application: A precision stencil printer applies solder paste to the PCB pads. The stencil is laser-cut from stainless steel to match the exact pad pattern of your board design.
  • Solder Paste Inspection (SPI): Before any components are placed, our 3D SPI system inspects every solder paste deposit for volume, height, area, and bridge detection. This prevents defects before they happen.
  • Component Placement: High-speed pick-and-place machines retrieve components from reels, trays, and tubes, then place them onto the solder paste deposits with micron-level accuracy at speeds up to 80,000 components per hour.
  • Reflow Soldering: The populated board passes through a multi-zone convection reflow oven. The carefully calibrated thermal profile melts the solder paste, creating reliable solder joints without damaging sensitive components.
  • Automated Optical Inspection (AOI): Every board undergoes 3D AOI to detect placement errors, tombstoning, insufficient solder, bridging, and missing components in real-time.

Different SMD Component Package Sizes

SMD components come in standardized package sizes. The most common resistor and capacitor packages include 0201 (0.6mm x 0.3mm), 0402 (1.0mm x 0.5mm), 0603 (1.6mm x 0.8mm), 0805 (2.0mm x 1.25mm), and 1206 (3.2mm x 1.6mm). IC packages include QFP, QFN, BGA, CSP, and SOT variants. Understanding these sizes is critical for designing PCBs optimized for automated SMT assembly.

Solder Paste

Solder paste is a mixture of tiny solder spheres suspended in a flux medium. The choice of solder paste affects joint reliability, thermal performance, and compliance with environmental regulations. We use both SAC305 (Sn96.5/Ag3.0/Cu0.5) lead-free paste and traditional Sn63/Pb37 eutectic paste depending on your application requirements. Proper solder paste storage (refrigerated at 0-10°C), warm-up time, and stencil life management are critical quality factors we meticulously control.

Pro Tip: For ultra-fine-pitch components (0.4mm pitch and below), we recommend Type 4 or Type 5 solder paste with smaller particle sizes for cleaner aperture release and reduced bridging risk.


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Through-Hole Assembly Design Rules

Through-Hole Technology (THT) involves inserting component leads through drilled holes in the PCB and soldering them on the opposite side. While SMT has become the dominant assembly method, THT remains essential for components that require strong mechanical bonds — such as connectors, transformers, electrolytic capacitors, relays, and high-power semiconductors.

THT components provide superior mechanical strength compared to their surface-mount counterparts, making them indispensable in applications subject to mechanical stress, vibration, or high current loads. Industrial control systems, power supplies, automotive electronics, and military equipment frequently require through-hole assembly.

Wave Soldering Design Considerations

Wave soldering is the primary method for soldering through-hole components at scale. The PCB passes over a molten solder wave that contacts the bottom of the board, filling the plated through-holes and creating reliable solder joints. Key design considerations include:

  • Maintain consistent component orientation to optimize wave solder flow direction
  • Ensure adequate spacing between through-hole components (minimum 2.54mm pitch recommended)
  • Avoid placing SMD components on the wave-solder side without appropriate solder thieves or selective pallets
  • Design proper thermal relief pads for ground-plane connections to prevent cold solder joints
  • Position connectors and tall components at the trailing edge of the board relative to wave direction

Manual Soldering

For prototype quantities, mixed-technology boards, or rework operations, skilled manual soldering by IPC-certified technicians is used. Our operators use temperature-controlled soldering stations with ESD protection, following IPC-A-610 Class 2 and Class 3 workmanship standards for every joint.

Mixed Assembly Advantages

Many modern PCBs use a combination of SMT and THT components — known as mixed assembly. This approach combines the high-density advantages of SMT with the mechanical robustness of THT. Our production lines are fully configured for mixed assembly workflows, including selective soldering systems that solder specific through-hole joints without affecting nearby SMT components.


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Turnkey PCBA Manufacturing

Our Turnkey PCBA service is a complete, hands-off solution where SMTWISE Technology manages every phase of your PCB project — from component sourcing and bare board fabrication to assembly, testing, and final packaging. You provide the design files; we deliver tested, production-ready assemblies.

Component Sourcing

We maintain a vast network of authorized distributors and verified suppliers across Asia, Europe, and North America. Our procurement team sources authentic, traceable components while actively managing lead times, minimum order quantities, and end-of-life (EOL) risks. For hard-to-find or obsolete components, we leverage our extensive cross-reference database to identify drop-in replacements that maintain electrical and mechanical compatibility.

PCB BOM File

A well-structured Bill of Materials (BOM) is the foundation of successful turnkey assembly. Your BOM should include: manufacturer part number, description, package/footprint, quantity per board, reference designators, and approved alternates. We review every BOM for completeness, availability, and potential cost optimizations before production begins.

Component Orientation and Polarity

Correct component orientation is critical to prevent board failures. Polarized components (electrolytic capacitors, diodes, LEDs, ICs) must be placed with correct polarity as indicated by the silkscreen markings on the PCB. Our AOI systems verify orientation against the design data, catching any placement errors before soldering.

Kitting Guidelines for PCB Assembly

If you prefer consigned assembly (you supply the components), proper kitting is essential. Components should be delivered in their original packaging with manufacturer labels intact. Include 5-10% overage for passive components to account for placement machine attrition. All moisture-sensitive devices (MSDs) must be vacuum-sealed with desiccant and humidity indicator cards per IPC/JEDEC J-STD-033.


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BGA Assembly

Ball Grid Array (BGA) packages are used for high-pin-count integrated circuits like FPGAs, processors, and SoCs. Unlike QFP packages with visible peripheral leads, BGA solder balls are hidden beneath the component body, making inspection challenging and requiring specialized equipment and expertise.

Our BGA assembly capabilities include precise solder paste deposition using stepped stencils, nitrogen-atmosphere reflow for improved wetting, and comprehensive X-ray inspection to verify solder joint integrity beneath every BGA component. We support both standard BGA (1.0mm and 0.8mm pitch) and micro-BGA/CSP packages down to 0.3mm pitch.

BGA Fanout

BGA fanout is the routing strategy used to escape signal traces from beneath the BGA footprint to the outer layers of the PCB. For high-pin-count BGAs, this typically requires via-in-pad technology with filled and capped microvias. Proper fanout design is critical for signal integrity, especially in high-speed digital applications.

Panel Requirements for PCB Assembly

To maximize throughput and minimize handling damage, individual PCBs are assembled in panels (arrays). Panel design must include adequate rails (minimum 5mm), fiducial markers for machine vision alignment, tooling holes for fixture registration, and appropriate breakaway tabs or V-score lines for depaneling. We support both tab-routed and V-scored panels.

Array Panelization

Array panelization involves arranging multiple PCB units into a single panel for efficient batch processing through the SMT line. The panel layout must balance material utilization with mechanical stability during assembly. We provide free panelization review and optimization as part of our DFM service.


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Flex & Rigid-Flex Assembly

Flexible and rigid-flex PCBs present unique assembly challenges due to their thin, bendable substrates. These boards are widely used in medical devices, aerospace systems, wearable electronics, and compact consumer products where space constraints demand three-dimensional circuit routing.

Rigid PCB Assembly

Standard rigid PCB assembly follows conventional SMT and THT processes on FR-4 or other rigid substrates. We handle single-sided, double-sided, and multi-layer rigid boards up to 40 layers with any combination of surface mount and through-hole components.

Flex PCB Assembly

Flex PCB assembly requires specialized handling fixtures (carriers or pallets) to maintain flatness during solder paste printing, component placement, and reflow. The thin polyimide substrate (typically 25-50μm) is fragile and susceptible to wrinkling, so our operators follow strict handling protocols. Component placement near bend areas must be avoided, and stiffeners are bonded to component areas to provide mechanical support.

Rigid-Flex Assembly

Rigid-flex assemblies combine rigid sections (with components) connected by flexible sections that fold into the final product enclosure. Assembly must account for the different thermal characteristics of rigid and flex sections during reflow. We use custom fixtures that support both rigid and flex zones simultaneously.

How to Select a PCB Cable Assembly

PCB cable assemblies connect circuit boards to other boards or external systems using flexible flat cables (FFC), flexible printed circuits (FPC), or wire harnesses. Selection depends on signal count, impedance requirements, bend radius, and connector type. We assist with cable assembly design, connector selection, and integration into your overall product architecture.


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Prototyping & Quality Testing

Our rapid prototyping service delivers assembled boards in as few as 48 hours, enabling fast design iteration and time-to-market acceleration. We support quantities from 1 to 100+ units with the same precision equipment and processes used in full production.

Automated Optical Inspection (AOI)

Our 3D AOI systems inspect 100% of assembled boards for solder joint quality, component presence/absence, correct orientation, polarity, and marking verification. The system compares each board against the golden reference image and flags any deviations for review.

PCB X-Ray Inspection

X-ray inspection is essential for verifying hidden solder joints beneath BGA, QFN, and LGA packages. Our high-resolution X-ray system can detect voiding, head-in-pillow defects, solder bridging, and insufficient solder on joints that are invisible to optical inspection.

E-Test (Electrical Testing)

Flying probe and bed-of-nails electrical testing verifies continuity, isolation, and impedance of every net on the bare PCB before assembly. This catches open circuits, short circuits, and impedance violations that could cause field failures.

What Are PCB Test Coupons?

Test coupons are small, standardized patterns fabricated on the same panel as your production boards. They are used for destructive testing — cross-sectioning to measure copper plating thickness, via barrel integrity, dielectric spacing, and solder mask registration — without sacrificing production boards. We include IPC-compliant test coupons on every panel.

Manufacturing Tolerances

Understanding manufacturing tolerances is critical for designing boards that are both high-performance and manufacturable. Key tolerances include minimum trace width/spacing (typically 3/3mil for standard, 2/2mil for HDI), drill size tolerance (±0.05mm), registration accuracy (±0.075mm), and impedance tolerance (±10% standard, ±5% controlled).

The SMTWISE Advantage

01. Advanced Equipment

Multi-zone reflow ovens, high-speed Yamaha and Fuji pick-and-place machines capable of handling 01005 components with absolute precision.

02. Expert Engineering

Decades of combined experience. Our R&D engineers assist with DFM/DFA to reduce costs and improve yield before production begins.

03. Turnkey Sourcing

Vast network of verified global suppliers to source authentic, hard-to-find ICs and passives, mitigating supply chain risks.

04. Strict Compliance

ISO certified processes ensuring every batch meets rigorous international quality and environmental standards including RoHS and REACH.

Ready to Start Your PCB Assembly Project?

Upload your Gerber files and BOM for an instant quote. Our engineers will review your design for free DFM/DFA feedback within 24 hours.

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