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SMT PCB Assembly
Surface-Mount Technology (SMT) is the core process of PCB Assembly (PCBA). Components are placed flat on copper pads and soldered in a single reflow cycle—no holes, no wave, delivering delivers high density, high speed, low cost and high reliability for mass production.
- Maximum panel size 54 inches
- Maximum panel thickness 0.450 inches
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Our SMT PCB Assembly Service
Zintilon offers advanced SMT assembly from prototype to small-batch. From solder-paste printing to final AOI, we provide efficient, reliable SMT solutions.
SMT PCB Assembly Materials
| Category | Typical Grade / Spec | Key Parameters | Notes |
| Solder paste | SAC305 (Type 4) | Melting 217–221 °C, Ag 3.0 % | Lead-free mainstream |
| Low-temp paste | SnBiAg (Type 5) | Melting 138–172 °C | For FPCs, temperature-sensitive LEDs |
| No-clean flux | ROL0 | Halogen 0 ppm, SIR >1×10¹² Ω | Automotive requirement |
| SMT adhesive (red glue) | EP-138 | Cure 150 °C / 90 s | Used only for second-side wave; pure SMT obsolete |
| Stencil | Laser + electro-polish 304 | 0.10–0.15 mm; area ratio ≥0.66 | Step stencil for 0.3 mm pitch |
| Nitrogen | N₂ 99.9 % | O₂ <500 ppm | Reduces voids & tombstones |
SMT PCB Assembly Surface Finishes
| Finish | Thickness | Solder | Key Points | Typical Use |
| ENIG | Ni 3–5 µm + Au 0.05 µm | ★★★★★ | Flat, wire-bondable, 12 mo shelf | BGA, fine-pitch, gold-wire |
| ENEPIG | +Pd 0.05 µm | ★★★★★ | Al/Au wire, highest reliability | Automotive, mil, 5G |
| OSP | 0.2–0.5 µm | ★★★☆☆ | Lowest loss, 6 mo shelf | RF, 0201/01005, low-cost |
| Immersion Ag | 0.15–0.3 µm Ag | ★★★★☆ | Low loss, sulfur-sensitive | 5G antenna, mmWave |
| HAL-LF | SnCu 1–2 µm | ★★★★☆ | Cheap, reworkable | Large-pad power boards, LEDs |
Why Choose Our
SMT PCB Assembly Service?
One-on-One Quotation
Simply upload your .gbr file to receive a quotation feedback within 24 hours. Our professional engineers will analyze your design to avoid misunderstandings, actively communicate with you, and provide a reasonable price.
High-Quality Production
We maintain a rigorous and responsible attitude toward materials, processes, surface treatments, A.O.I, and flying probe testing, ensuring consistent high quality from prototype manufacturing to mass production.
Fast Delivery
Equipped with advanced machinery and a professional engineering team to ensure fast delivery. We prioritize orders based on requirements and complexity. Customized delivery solution is also available to tailored to your needs.
Instant Communication
For your benefit, we provide full-cycle technical support for each customer from quotation to delivery. We will respond quickly to any questions until you confirm satisfactory SMT PCB assembly.
SMT PCB Assembly Tolerances
and Standards
Zintilon provides advanced SMT PCB assembly from prototyping to small-batch production. From raw-material cutting to final packaging, we deliver efficient and reliable smt PCB assemly solutions no matter single-layer PCB or multilayer PCBs.
Component Placement
Spec Component shift
Source/Remarks ≤25 % pad width for chip parts (IPC Class 2)
Spec QFP/BGA offset
Source/Remarks ≤15 % pad width
Spec Same component orientation
Source/Remarks align along X or Y to reduce pick-place rotation
Spec Edge clearance
Source/Remarks ≥3 mm (V-cut side ≥5 mm) to avoid conveyor clamps
Spec BGA keep-out
Source/Remarks ≥3 mm from board edge, slots, mounting holes
Spec Heavy parts
Source/Remarks spread symmetrically, center of gravity on PCB neutral axis
Spec Heaters
Source/Remarks ≥1 W devices spaced ≥5 mm; sensitive parts ≥10 mm from heat sources
Pads & Stencil
Spec Stencil thickness
Source/Remarks 0.10–0.15 mm; 0.3 mm pitch use 0.08 mm step-down
Spec Area ratio
Source/Remarks round aperture ≥0.8, rectangular ≥0.66
Spec BGA pads
Source/Remarks diameter = 0.8–1.0 ball diameter; no via-in-pad or plated-filled only
Spec 0201/01005
Source/Remarks use IPC-7351 “NSMD” library, 0.05 mm rounded corners
Reflow Profile (SAC305 Lead-Free)
Spec Ramp
Source/Remarks 1–3 °C/s
Spec Soak
Source/Remarks 150–190 °C, 60–90 s
Spec Peak
Source/Remarks 235–245 °C
Spec Time above liquidus
Source/Remarks 40–70 s
Spec Cooling
Source/Remarks ≤6 °C/s
SMT PCB Assembly Guidelines
Ensure precise tolerances, select appropriate materials, maintain clear CAD designs, and follow IPC for best results. Zintilon delivers accuracy, quality, and consistency in every SMT PCB assembly.
Item
Spec
Source/Remarks
Chip Component Offset
Spec ≤ 25% of Pad Width
Source/Remarks IPC-A-610 G Class 2
QFP/BGA Offset
Spec ≤ 15% of Pad Width
Source/Remarks High-Precision Vision Alignment System Acceptance
Orientation of Similar Components
Spec Uniformly along X or Y axis, with consistent polarity direction
Source/Remarks Reduce placement machine rotation axis movements and lower component mismatch rate
Component to Board Edge
Spec ≥ 3 mm (≥ 5 mm for V-CUT edges)
Source/Remarks Prevent component damage from conveyor clamps and board splitting/cracking
BGA Keep-Out Area
Spec ≥ 3 mm from board edges, slots, and mounting holes
Source/Remarks Avoid high-stress areas and prevent solder joint cracking
High-Mass Components
Spec Distributed and symmetric layout, with center of gravity aligned to PCB geometric center
Source/Remarks Reduce warpage after reflow and conveyor jamming
Heat-Generating Components
Spec ≥ 5 mm spacing between each other when power ≥ 1 W; ≥ 10 mm distance between sensitive components and heat sources
Source/Remarks Reduce local thermal island effect
Our SMT PCB Assembly Service for Various Industrial Applications
Prototyping and production parts from Zintilon have been applied to the various walks of life. The brilliant SMT PCB assembly service simplifies the process of obtaining good-quality production PCB assembly components.
SMT PCB Assembly FAQs
We cooperate with multiple certification bodies and can handle CE certification, FCC certification, RoHS certification, FDA certification, etc.
We have a highly professional engineering team with extensive design experience in fields such as industrial control, consumer electronics, new energy, and medical devices.
Throughout the product development process, we confirm each step with the client. If the project design includes sample testing, we will conduct electrical performance testing, functional testing, performance testing, and reliability testing to ensure design quality.
Got any more questions?
Ultimate Guide
to SMT PCB Assembly
to SMT PCB Assembly
SMT PCB Assembly Manufacturing
Various and Robust SMT PCB Assembly Services
Prototype
Prototyping
From Gerber files to circuit boards, our professional engineering team provides you with the highest quality rigid PCB manufacturing services. We meticulously control every detail of the process, including drilling, electroplating, and AOI, ensuring precise control over trace spacing, thickness, and panel dimensions. We are committed to providing you with the most reliable PCB assembly.
- Complete production line
- Professional engineering support
- 10+ years‘ manufacturing experience
Production
Production
We have our own production lines and a robust manufacturing network. From PCB design, engineering, and manufacturing, we have sufficient capacity to provide you with professional and fast delivery services, whether for small or large batches. We spare no effort in providing consistent mass production services for your products.
- Strong supply chain team
- Competitive pricing
- One-stop service from design to delivery
Let’s Build Something Great, Together
