SMT sides and THT access
Map component side, height, weight, thermal limits and solder access so later operations do not disturb previously formed joints.
PCB Assembly technology / integrated process sequence
Mixed Technology PCB Assembly
Mixed technology PCB assembly combines surface-mount placement with through-hole, press-fit, odd-form or hand operations. The process succeeds when every thermal and mechanical step is sequenced around the released board, component mix and acceptance plan.
SMT + THTIntegrated assembly route
Wave / selectiveSolder method chosen by access
Press-fit / odd-formMechanical operations by package
Risk-basedInspection and test evidence
At a glance
What is mixed technology PCB assembly?
A mixed-technology assembly contains more than one component or connection route. It may combine top- and bottom-side SMT, through-hole connectors, press-fit contacts, transformers, relays, hardware, cable interfaces or parts that require controlled hand operations. The correct route is not simply “SMT first, THT second”; it is a documented sequence that protects earlier joints and sensitive components during every later step. PCBArise already publishes SMT, THT/DIP, BGA, QFN, press-fit and odd-form scope within its assembly capability reference. This page turns those individual capabilities into a commercial service decision: which files are needed, how soldering methods are chosen, what must be reviewed before quotation and what evidence should follow the finished build.
Engineering choices
Select the sequence before selecting individual operations.
Every additional soldering or mechanical operation can change board support, thermal exposure, component clearance and inspection access. The sequence should be designed as one system.
Reflow, wave, selective or hand
Choose the method from keep-outs, connector geometry, board mass, underside population, alloy and workmanship requirements.
Press-fit and odd-form control
Define tooling, force, support, orientation, hardware and inspection requirements for parts outside automated placement.
Evidence after each critical step
Place inspection and testing where failures can still be detected and corrected without assuming the final visual check covers the whole route.
Technical reference
Mixed-technology assembly reference
Use this reference to prepare a credible quotation package. Final sequence, method, fixtures, line assignment and acceptance evidence remain project-specific.
Mixed-technology assembly reference
Final scope, limits and evidence are confirmed from the released build package.
| Required quote package | Gerber or ODB++, BOM, CPL/centroid data, assembly drawing, mechanical drawings and available programming or test requirements. |
|---|---|
| Component classification | SMT, through-hole, press-fit, odd-form, hardware and manual-install items identified by reference designator and side. |
| SMT sequence | Top- and bottom-side print, placement and reflow reviewed with package weight, adhesive needs, board support and later solder exposure. |
| Through-hole route | Wave, selective or hand soldering selected from component geometry, underside keep-outs, thermal mass and required workmanship. |
| Press-fit operations | Connector, compliant-pin, insertion force, tooling, backing support and verification defined from approved component data. |
| Odd-form handling | Orientation, lead forming, clinching, fastening, adhesive, clearance and manual or automated handling requirements documented. |
| Board support | Panel rails, pallets, carriers, tooling holes, fiducials and underside clearance reviewed for every thermal and insertion step. |
| Process protection | Masking, heat shields, temporary fixtures or sequencing used only when the released design and process review require them. |
| Inspection plan | SPI, AOI, X-ray and visual methods placed where each can observe the intended feature or joint. |
| Test and programming | ICT, flying probe, firmware loading and functional testing included when procedures, files, fixtures and limits are available. |
Integrated assembly sequence checkpoints
The exact flow changes by design; these stages show the decisions that must be closed rather than prescribing one universal recipe.
| 1. File and revision review | Reconcile fabrication data, BOM, CPL, drawings, mechanical information and no-fit instructions. |
|---|---|
| 2. Material and tooling plan | Confirm package, board, stencil, pallet, carrier, insertion tool, fixture and handling requirements. |
| 3. SMT operations | Run the approved print, placement and reflow sequence for each populated side. |
| 4. THT and mechanical operations | Insert, press-fit, fasten or form components using the selected support and process controls. |
| 5. Secondary soldering | Apply wave, selective or hand soldering where access and thermal constraints support the method. |
| 6. Inspection and cleaning | Use the approved visual, automated, X-ray and cleanliness evidence at the relevant checkpoints. |
| 7. Programming and test | Execute the released firmware and electrical or functional procedures with defined limits and records. |
Design context
Later operations must not invalidate earlier process evidence.
A surface-mount section may pass AOI and still be damaged during a later insertion, selective-solder or manual operation. Mixed assembly planning therefore connects thermal exposure, mechanical force, access and inspection checkpoints. Compare the foundation on SMT Assembly and Through-Hole Assembly, then use the mixed route to resolve their interfaces.
- Identify both assembly sides, component height and underside keep-outs.
- Confirm which joints are formed by reflow, wave, selective or hand soldering.
- Define carriers, pallets, backing support, insertion tools and fixtures before release.
- Place inspection and testing after the operations that create the relevant risk.
Engineering review
What the mixed-technology engineering review should close
The final process plan should make ownership, sequence, tooling and evidence visible before a mixed build enters production.
BOM, CPL, drawing and side information identify every automated and manual operation.
The SMT sequence accounts for package weight, underside population and later heating.
Wave, selective and hand-solder choices match keep-outs, geometry and thermal constraints.
Press-fit and odd-form components have approved handling, tooling and support instructions.
Board and panel support remain valid through printing, reflow, insertion and soldering.
Cleaning, masking, coating or hardware operations are sequenced around component restrictions.
Inspection checkpoints are assigned to the defects each method can actually detect.
Programming, ICT or functional-test inputs are complete before the quotation schedule is confirmed.
Practical fit
Where mixed technology assembly fits
Use the route when automated placement and mechanically robust or high-power connections must coexist on the same released assembly.
Industrial control
Combine dense control electronics with terminal blocks, relays, connectors and serviceable through-hole interfaces.
Power electronics
Coordinate large thermal masses, power devices, magnetics, bus connections and control-side SMT populations.
Automotive electronics
Connect high-density packages, robust connectors and project-specific inspection or test evidence.
Test and measurement
Integrate precision SMT circuits with connectors, mechanical controls and defined calibration or functional checks.
BGA plus THT builds
Place hidden-joint packages within a route that also includes connectors, press-fit or secondary soldering.
Prototype to repeat production
Capture first-build learning in tooling, sequence, workmanship and test records before scaling.
Frequently asked questions
Questions that shape the mixed technology pcb assembly route
Use these answers to define the process route without assuming all mixed assemblies follow one fixed sequence.
What makes a PCB assembly mixed technology?
A mixed assembly combines process families such as SMT and through-hole, or adds press-fit, odd-form, hardware and controlled manual operations. The defining feature is the need to coordinate their sequence and interfaces.
Does SMT always run before through-hole assembly?
Often, but not unconditionally. Side population, component weight, adhesive, solder access, thermal limits, carriers and later mechanical operations can change the approved sequence.
How do you choose between wave, selective and hand soldering?
The decision depends on component and lead geometry, underside keep-outs, board thermal mass, alloy, access, quantity, workmanship requirements and the evidence needed for acceptance.
Can BGA packages be included on a mixed-technology board?
They can be evaluated as part of the SMT route. The BGA land pattern, print, reflow and hidden-joint inspection plan must remain compatible with the THT and secondary operations that follow.
What files help define press-fit or odd-form operations?
Provide approved component data, assembly and mechanical drawings, orientation, insertion or fastening requirements, tooling information and inspection or test criteria in addition to the standard PCB assembly package.
Related pages
Review each process family that shapes the mixed route.
Use the connected pages to resolve surface-mount, through-hole, BGA and acceptance decisions before release.
PCB Assembly
SMT Assembly Services
SMT assembly services for fine-pitch, BGA and mixed-technology PCBA, with file review, stencil, placement, reflow, inspection and test planning.PCB AssemblyThrough-Hole PCB Assembly (THT)
Through-hole PCB assembly service for connectors, relays, transformers and high-mass parts, with wave, selective or hand soldering and test planning.PCB AssemblyBGA Assembly Services
BGA assembly services for fine-pitch packages, with stencil, placement, reflow, X-ray inspection and build-specific engineering review for prototype and production PCBA.PCB AssemblyPCB Assembly Testing Services
PCB testing services including SPI, AOI, AXI, ICT, flying probe, FCT and project-specific functional test plans for assembled boards.Map the full mixed-technology route before quotation.
Share the released PCB files, BOM, CPL, assembly and mechanical drawings, plus programming and test requirements so every SMT, THT and secondary operation can be reviewed together.