Through Hole PCB Assembly Service , PCB Board Assembly Manufacturing

While Surface Mount Technology (SMT) dominates modern miniaturization, Through-Hole Technology (THT) remains the undisputed champion for mechanical reliability and high-power applications.

DuxPCB provides industry-leading Through-Hole assembly services, blending the precision of automated insertion with the craftsmanship of skilled manual assembly. Whether you need rugged connectors for industrial controllers, heavy transformers for power supplies, or legacy components for aerospace avionics, our THT process ensures the strongest possible mechanical bond between the component and the PCB.

We don't just "stuff boards"; we engineer connection integrity. From automated Axial/Radial Insertion to advanced Selective Soldering, DuxPCB delivers the robust performance required for harsh environments.

Designers choose Through-Hole not for size, but for Survival.

1. Mechanical Durability
SMT components rely on surface solder. THT components pass through the board, providing a mechanical anchor. This is non-negotiable for connectors, switches, and heavy capacitors that face constant physical stress, vibration, or plug-in/plug-out cycling.

2. High-Power Handling
For power electronics (EV Chargers, Inverters), THT leads can handle significantly higher current and thermal loads than surface mount pads.

3. Environmental Resilience
THT solder joints are larger and more robust, making them less susceptible to thermal shock and fatigue in extreme temperature environments (-40°C to +125°C).

We support High-Mix/Low-Volume (Manual) and High-Volume (Automated) production lines.

Through-Hole assembly is more complex than SMT because it requires 3D manipulation of components. Our process controls ensure consistency.

Components often come in bulk or ammo packs.

• Pre-forming: We utilize automated lead-forming machines to cut and bend leads to the exact pitch required by your PCB layout.

• Stress Relief: We form "kinks" or standoffs in the leads to prevent thermal stress from cracking the component body during soldering.

• Auto-Insertion: For high-volume resistors and capacitors, our Axial/Radial machines insert components at high speed, clinching the leads underneath to secure them before soldering.

• Manual Insertion: For odd-form parts (transformers, connectors), our operators use visual aids and fixture templates to ensure correct polarity and alignment.

We offer three distinct soldering methods depending on your board density and volume:

• Wave Soldering: The standard for mass production. Boards pass over a molten wave of solder. We use custom Solder Pallets (Fixtures) to shield bottom-side SMT parts from the wave.

• Selective Soldering (The High-End Choice): For boards that are too dense for wave soldering fixtures, we use robotic Selective Soldering. A mini solder nozzle moves to specific points, soldering individual THT pins without thermally shocking nearby SMT components. This is essential for high-reliability/automotive boards.

• Hand Soldering: Used for temperature-sensitive components or final assembly steps.

Flux residue can be corrosive.

• Inline Wash: We use high-pressure aqueous cleaning systems to remove flux residues.

• AOI & Visual: We inspect for "Solder Fillet" quality (barrel fill > 75% for Class 2, > 100% for Class 3), solder bridges, and lifted pads.

Many EMS providers only offer Wave Soldering or Hand Soldering. DuxPCB invests in Selective Soldering technology.

Why is this important?

1. Precision: It allows us to solder THT parts on double-sided boards populated with fine-pitch SMT components on the bottom side.

2. Reliability: It provides reproducible machine quality (temperature, dwell time) that hand soldering cannot match.

3. Cleanliness: It applies flux only where needed, reducing contamination.

THT defects are often structural. We test rigorously.

• Pull Testing: We periodically perform destructive pull tests to verify the mechanical strength of the solder joint.

• Solder Fillet Inspection: We strictly adhere to IPC standards regarding vertical fill (the solder must rise through the hole to the top side).

• Heatsink Verification: For TO-220/247 power devices, we check torque on mounting screws and verify thermal paste application to ensure proper heat transfer.

• Industrial Controls: High-voltage inputs, Relay logic boards, VFDs.

• Power Supplies: Heavy transformers, Large electrolytic capacitors, Power inductors.

• Automotive: Heavy-duty connectors, Ignition systems.

• Audio Equipment: High-fidelity amplifiers using through-hole capacitors and tubes.

• Military/Aerospace: Legacy avionics systems requiring extreme vibration resistance.

Q: Do you support "Mixed Technology" (SMT + THT) assembly?
A: Yes, 95% of our projects are Mixed Technology. We typically perform SMT reflow first, followed by THT assembly (Wave or Selective soldering).

Q: What is the difference between Wave Soldering and Selective Soldering?
A: Wave soldering passes the entire board over molten solder (fast, good for simple boards). Selective soldering uses a robotic nozzle to solder specific points (precise, ideal for dense, double-sided boards). We will recommend the best method based on your layout.

Q: Can you handle Leaded (SnPb) soldering for military legacy products?
A: Yes. We maintain dedicated solder pots for Leaded solder to prevent cross-contamination with our RoHS/Lead-Free lines.

Q: Do you provide Component Pre-forming/Bending services?
A: Yes. We have automated forming equipment. We never manually bend leads against the component body, as this can damage the internal seal. We always follow IPC lead-forming guidelines.

Don't let a weak solder joint be the failure point of your product. Choose a partner who treats Through-Hole assembly with modern engineering precision.

Send your Gerber and BOM to DuxPCB. Our engineers will review your design for Wave Solder Pallet feasibility and provide a comprehensive quote.