Fine-pitch SMT ICs and mechanically robust THT connectors, on the same board, in the same production run — engineered process sequencing eliminates the hand-off errors that come from splitting SMT and THT across two vendors.
Any product combining logic-level electronics with rugged connectors or power components needs mixed assembly. Hover to explore.
Relay modules and body controllers combine fine-pitch driver ICs with press-fit power connectors and screw terminals in a single hybrid build.
Diagnostic instruments pair SMT sensor front-ends with THT battery holders, fuse clips and locking connectors that must survive repeated handling.
Motor drives and PLC I/O cards need SMT control logic alongside THT terminal blocks and heavy connectors rated for field wiring.
Appliances and power tools mix dense SMT control boards with THT switches, motor leads and mechanically-stressed jacks.
Base station and power supply boards combine RF SMT modules with high-current THT connectors and chassis-mount hardware.
Avionics and rugged comms gear demand IPC Class 3 mixed assembly — fine-pitch SMT plus mil-spec THT connectors, fully traceable.
Smart-home hubs and gateways combine BLE/Wi-Fi SMT modules with THT power jacks, antennas and battery connectors.
Inverters and charge controllers pair SMT control loops with THT power switching devices, chokes and busbar terminals.
Mixed assembly isn't two separate jobs bolted together — it's one engineered process where the order of operations determines the yield.
Before any board is built, our process engineers plan the solder-paste-vs-wave sequence for your specific BOM — deciding which SMT parts go through reflow first, which side is populated first on double-sided boards, and where thermal exposure limits require paste-in-hole or selective soldering instead of full wave.
Stack-up review · thermal budget · sequencing planSolder paste printing, high-speed pick-and-place down to 01005 passives and 0.4mm-pitch fine-pitch ICs, followed by a nitrogen-assisted reflow profile tuned to your paste alloy and board mass.
01005 min · 0.4mm pitch · N2 reflowThrough-hole components are inserted — by machine where possible, by hand for connectors and mechanical hardware — then soldered by wave or selective soldering. On dense boards where SMT joints sit close to THT pads, we default to selective soldering to eliminate bridging risk and keep heat away from parts already reflowed.
Wave or selective · bridging-safe · thermally isolatedLarge connectors, heat-sinked power devices and any joint outside automated coverage are hand-soldered by IPC-A-610 certified operators, followed by no-clean or aqueous cleaning and a full AOI, X-ray and functional test pass before the board leaves the line.
IPC-A-610 hand-solder · AOI · X-ray · function testEvery stage — SMT, THT and rework — runs in-house on one production floor.
Multiple high-speed pick-and-place lines with fine-pitch and 01005 capability, solder paste inspection (SPI) after printing, and nitrogen reflow ovens with closed-loop thermal profiling for every recipe.
Automated wave soldering for boards with clear THT-only zones, and selective soldering cells for dense mixed boards where nearby SMT joints can't tolerate wave immersion. Both processes run with nitrogen assist to control dross and joint quality.
ESD-safe manual soldering benches staffed by IPC-A-610 Class 2/3 certified operators for large connectors, heat-sinked devices and any component outside automated process coverage, backed by dedicated BGA and fine-pitch rework stations.
Every parameter below is verified against IPC-A-610 and J-STD-001 requirements. Full inspection and test reports ship with every order.
| Parameter | Mixed Assembly Grade | Status |
|---|---|---|
| SMT Component Size | 01005 to large-body BGA/QFP | Available |
| SMT Min Pitch | 0.4 mm fine-pitch | Available |
| THT Lead Diameter | 0.6 mm – 3.0 mm | Available |
| Board Type | Single or double-sided mixed tech | Available |
| Layer Count | 2 – 20 layers | Available |
| Max Board Size | 500 mm x 400 mm | Available |
| Solder Process | Reflow + wave / selective + hand-solder | Available |
| IPC Build Standard | Class 2 default · Class 3 on request | Available |
| Standard Lead Time | 5 – 7 working days | Available |
Mixed-technology boards carry the risk of two different failure modes on one assembly. Our QMS treats SMT and THT joints with the same rigor — full inspection coverage on both, every batch.
Real mixed-technology assembly challenges — and how we solved them.
Double-sided board combining a 0.4mm-pitch microcontroller with THT screw terminals and IGBT modules. Selective soldering used to protect nearby SMT joints from wave heat.
Switching from wave to selective soldering on the SMT-adjacent zone eliminated a recurring bridging defect the customer's previous supplier could not resolve.
SMT sensor front-end plus THT battery clips and a locking power connector. Single-vendor build removed the hand-off between separate SMT and THT suppliers used previously.
Consolidating SMT and THT under one process owner cut lead time by 4 days and removed a recurring connector-alignment defect tied to the previous two-vendor hand-off.
12-layer board pairing SMT MPPT control logic with THT power switching devices, chokes and busbar terminals rated for continuous high current.
100% X-ray inspection of THT barrel fill on the busbar terminals caught a marginal solder-fill batch before shipment, avoiding a field failure under load.
Mixed-technology assembly punishes vendors who treat SMT and THT as separate jobs. We plan the whole sequence up front, so process order — not luck — is what protects your yield.
Splitting SMT and THT across two vendors means two shipping legs, two sets of process notes and two chances for a connector to be misaligned or a joint to be missed. We run both in one facility, under one process owner.
Our engineers map the reflow-vs-wave-vs-selective sequence against your BOM's thermal limits within 12 hours of file receipt — so no already-soldered SMT joint is ever put back through unnecessary heat.
On dense boards where wave soldering could bridge nearby SMT joints, we default to selective soldering — a small process choice that consistently protects yield on complex mixed boards.
Full turnkey sourcing for both SMT and THT components, fabrication and assembly under a single purchase order and a single point of contact.
Common questions about mixed-technology SMT + THT assembly.
Mixed assembly refers to a single PCB that carries both surface-mount (SMT) and through-hole (THT) components, assembled in the same production run. We reflow the SMT side first, then insert and solder the THT components by wave, selective soldering or hand-solder — sequenced so earlier joints aren't damaged by later thermal steps.
Splitting the job adds a shipping leg, a second inspection point and a real risk of process notes getting lost between vendors — a common cause of misaligned connectors or missed touch-up joints. Running both processes under one roof removes that hand-off entirely and typically shortens lead time by several days.
Both, chosen per board. Full wave soldering is efficient for boards with a clear THT-only zone. On dense boards where SMT joints sit close to THT pads, we use selective soldering instead — it applies solder only where needed, avoiding bridging on nearby fine-pitch joints and keeping thermal exposure localized.
Yes. Double-sided mixed-technology boards are common — for example SMT on both sides with THT connectors on one side. We plan the reflow order (which side goes first) and use adhesive or fixturing as needed to keep bottom-side SMT components in place through the second reflow pass.
This is exactly what our DFM sequencing review addresses before production starts. We assess which SMT components sit near THT pads, select wave versus selective soldering accordingly, use thermal shielding or pallet fixtures where needed, and validate the profile on a first-article board before full production.
Gerbers or ODB++, a full BOM with SMT and THT parts clearly identified, centroid/pick-and-place data, and assembly drawings noting any special mounting or connector orientation requirements. If you can flag which components are height- or heat-sensitive, our sequencing review moves even faster.
Our process engineering team will review your BOM and stack-up, plan the SMT/THT sequencing, and return a full quote and DFM report within 12 working hours.
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