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Mixed PCB Assembly
Mixed PCB Assembly refers to an assembly process that adopts both Surface Mount Technology (SMT, featuring high density and thinness) and Through-Hole Technology (THT, featuring high power and high mechanical strength) on the same circuit board.
- Maximum panel size 54 inches
- Maximum panel thickness 0.450 inches
- High-density layout, high-current carrying capacity, and high reliability
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Our Mixed PCB Assembly Service Capabilities
Mixed PCB Assembly (hybrid PCB assembly) relies on four core advantages: "strong process compatibility, wide carrying range, outstanding reliability, and flexible scenario adaptation". It has become an "all-round assembly solution" for electronic equipment, covering all-dimensional application scenarios from consumer electronics to special industries.
Mixed PCB Assembly Materials
| Layer | Recommended Model/Specification | Key Parameters | Remarks |
|---|---|---|---|
| Substrate | High Tg FR-4 (e.g., Shengyi SY-1140, Taiguang TU-872) | Glass transition temperature (Tg) ≥ 170°C, thermal decomposition temperature (Td) ≥ 340°C | It needs to undergo reflow soldering and wave soldering successively, so the heat resistance of the material must match both processes |
| Copper Foil | Reverse Treated Foil (RTF) (≤ 3 oz) | Surface roughness (Ra) ≤ 4 μm, elongation ≥ 25% | Meets the requirements of SMT fine circuit production and THT high-current carrying capacity |
| Local Thermal Dielectric Layer | TC-350, IT-180A | Thermal conductivity: 2-3 W/m·K, coefficient of thermal expansion (CTE): 13-15 ppm/°C | Used for local lamination under power devices to enhance heat dissipation |
| Solder Mask Ink | Halogen-free black Laser Direct Imaging (LDI) ink | Withstands 288°C high temperature for 10 seconds, hardness ≥ 6H | Prevents ink from falling off due to impact during the Hot Air Leveling (HAL) process |
| SMT Adhesive (for Glue Fixing + Wave Soldering Process) | EP-138 Heat-Curing Adhesive | Cures at 150°C for 90 seconds, shear strength ≥ 15 MPa | Only used in the “glue fixing of SMT components + wave soldering” process, and has been eliminated in pure SMT processes |
Mixed PCB Assembly Surface Finishes
| Area | Process Combination | Thickness | Purpose |
|---|---|---|---|
| Entire Board | ENIG (Electroless Nickel Immersion Gold) | Ni 3–5 μm + Au 0.05 μm | Flat surface of SMD (Surface Mount Device) areas, suitable for wire bonding |
| Large Pads/Power Areas | HAL-LF (Lead-Free Hot Air Leveling) | SnCu 1–2 μm | Good wetting of hole walls, low cost |
| Gold Fingers | Selective Hard Gold Plating | Ni 3–5 μm + Au 0.5–1.5 μm | Wear-resistant, with ≥ 10,000 insertion cycles |
| RF Microstrips | OSP (Organic Solderability Preservative) | 0.2–0.3 μm | Minimum skin effect loss |
Why Choose Our Mixed PCB Assembly Service?
One-on-One Quotation
Simply upload your .gbr file, and you will receive a quotation feedback within 24 hours. Our professional engineers will analyze your design to avoid misunderstandings, communicate with you, and provide a reasonable price.
High-Quality Assembled
We maintain a rigorous and responsible attitude towards materials, processes, surface treatments, A.O.I (Automated Optical Inspection), and flying probe testing, ensuring consistent high quality from prototype production to mass production.
Fast Delivery
Equipped with advanced machinery and a professional quotation team to ensure fast delivery. We prioritize orders based on order requirements and complexity. Cutomized delivery sulution is also available.
Real-Time Communication
For your benefit, we provide full-process technical support for each customer from quotation to delivery. We will respond quickly to any of your questions until you confirm that you have received satisfactory Mixed PCB Assembly products.
Mixed PCB Assembly Standards
We follow the tolerance standards of ISO 2768 (medium grade, fine grade) and ISO 286 (grade 8, 7, 6). You are welcome to emphasize it in the drawings or communicate with the sales for higher precision needs. We follow ISO2768m by default in the absence of special requirements.
Item
Subitem
Spec
DFM Spacing & Dimensions (IPC-2221 + IPC-7351)
Recommended Value for Mixed Assembly Hole dia
IPC Source D + 0.20 mm (eco) | D + 0.15 mm (hi-rel)
Recommended Value for Mixed Assembly Annular ring
IPC Source ≥0.20 mm (Cl 2) | ≥0.25 mm (Cl 3)
Recommended Value for Mixed Assembly Hole copper
IPC Source ≥25 µm (1 oz) | ≥35 µm (auto/large current)
Recommended Value for Mixed Assembly SMD-to-THT edge
IPC Source ≥1.0 mm | ≥1.5 mm (anti-wave shadow)
Recommended Value for Mixed Assembly THT-to-board-edge
IPC Source ≥3 mm | ≥5 mm (V-cut side)
Recommended Value for Mixed Assembly Heavy parts
IPC Source symmetrical placement, CG on PCB neutral axis, warp ≤0.75 %
Thermo-Mechanical Co-Design
Recommended Value for Mixed Assembly Copper balance
IPC Source areal density difference ≤10 %, anti-reflow warpage
Recommended Value for Mixed Assembly Lamination
IPC Source pre-fill resin in thick-copper zones, no resin starvation
Recommended Value for Mixed Assembly Thermal cycling
IPC Source –55 ↔ +125 °C, 1 000×, ΔR ≤5 % (IPC-TM-650)
Recommended Value for Mixed Assembly Vacuum wave
IPC Source 5 mbar / 10 s for automotive large pads, voids <1 %
Mixed PCB Assembly Guidelines
Ensure precise tolerances, select appropriate materials, maintain clear CAD designs, and follow toolpath optimization for best results. Zintilon delivers accuracy, quality, and consistency in every machined part.
Item
Recommended Value for Mixed Assembly
IPC Source
Remarks
Hole Diameter
Recommended Value for Mixed Assembly D + 0.20 mm (for round pins)
IPC Source IPC-2221
Remarks Suitable for both automatic insertion and manual insertion
Pad Annular Ring Width
Recommended Value for Mixed Assembly ≥ 0.20 mm (Class 2)
IPC Source IPC-2221
Remarks Prevents annular ring breakage during HAL
Hole Copper Thickness
Recommended Value for Mixed Assembly ≥ 25 μm (1 oz)
IPC Source IPC-6012
Remarks Use 35 μm when current > 2 A
SMD Pads
Recommended Value for Mixed Assembly In accordance with IPC-7351 naming library (N density)
IPC Source IPC-7351
Remarks Directly call the package to reduce DFM (Design for Manufacturability) rework
Component Spacing (Mixed)
Recommended Value for Mixed Assembly SMD-to-THT ≥ 1.0 mm; THT-to-edge ≥ 3 mm
IPC Source IPC-2221
Remarks Avoids automatic insertion clamping jaws and wave soldering nozzles
Glue Fixing + Wave Soldering
Recommended Value for Mixed Assembly Adhesive dot: Ø 0.6 mm, height 0.3 mm, distance from pad 0.4 mm
IPC Source Production Line Experience
Remarks Prevents adhesive from spreading to pads and avoids cold soldering
Wave Soldering Direction
Recommended Value for Mixed Assembly Place THT tall components (> 15 mm) at the rear, low components at the front
IPC Source IPC-A-610
Remarks Reduces bridging caused by the shadow effect
Test Points
Recommended Value for Mixed Assembly Reserve 1.0 mm bare copper on both sides, ≥ 0.5 mm away from components
IPC Source IPC-2221
Remarks Shared by ICT (In-Circuit Test) and A.O.I
Warpage
Recommended Value for Mixed Assembly ≤ 0.75% after reflow soldering; ≤ 1.0% after wave soldering
IPC Source IPC-A-610 G
Remarks Use furnace fixtures and copper balance to control
Our Mixed PCB Assembly Service for Various Industrial Applications
Prototyping and production parts from Zintilon have been applied to the various walks of life. The brilliant custom CNC machining service simplifies the process of obtaining good-quality production parts.
Mixed PCB Assembly FAQs
Our maximum CNC machining part size is 3000 mm x 2200 mm x 1100 mm.
Our CNC machining standard tolerances range from plus or minus 0.001mm.
The cost of CNC machining is determined by the material, machining costs, labor costs, and the tooling and surface finish involved. Feel free to contact us for a quick quote.
Got any more questions?
Ultimate Guide
to Mixed PCB Assembly
to Mixed PCB Assembly
Mixed PCB Assembly Service
Various and Robust CNC Machining Services
Process 1
Prototyping
Zintilon's rapid prototype service bridges the gap between product concept and market during the product development. Advanced CNC machines such as Hermle 5 axis cnc milling centers, multiple international certifications, and top-notch CMM inspection ensure the accuracy and details of the prototype, meeting high standards of quality requirements.
- Advanced Technology: CNC, CMM inspection, elite engineers etc.
- Quick Response: full support to ensure problem solved.
- Customized service: customize precision machining solutions
Process 2
Production
Zintilon's on-demand production solution provides customers with a modern, efficient and customer-oriented production solution through its flexibility, high quality standards by our robust supply network and self-owned CNC shop, strict quality control inspection, etc.
- Reasonable planning: precision resource allocation to ensure quick cycle time.
- Machining SOP : advanced technology and strict QC processes.
- Flexible Production: from rapid prototyping (1-20pcs) to low-volume production (20-1000pcs).
Let’s Build Something Great, Together
