IN Brief:
- SAKI’s 3Di-LS3BX examines through-hole solder joints and surface debris after selective, wave or dip soldering without board flipping.
- The 15µm optical resolution is not a defect-detection limit; SAKI separately specifies solder-ball detection down to 200µm.
- Standard boards reach 510 × 510mm and 2kg, while a two-step scan supports 510 × 720mm and optional weight-transfer rails allow up to 12kg.
SAKI Corporation has launched the 3Di-LS3BX, an inline three-dimensional automated optical inspection system for the underside of assembled printed circuit boards. The machine is intended for inspection after selective, wave and dip soldering processes, particularly where through-hole components make conventional board handling difficult. It measures solder joints and checks for unwanted material without requiring the board to be turned over between process stages.
Through-hole solder inspection differs from the checks normally performed immediately after surface-mount reflow. Component leads extend through plated holes, and the solder fillet on the underside can show non-wetting, void-like pinholes, bridges or excessive material. A two-dimensional image can establish contrast and shape at the visible surface, but height information helps distinguish defects with similar appearances. SAKI has designed the new system around three-dimensional measurement of pins and solder fillets, with specialised algorithms for this inspection task.
The 3Di-LS3BX uses a rigid gantry and dome illumination to inspect reflective solder fillets and surfaces with slopes or irregular shapes. Reflected light varies with the viewing angle, making apparent brightness an unreliable measure of joint geometry. Three-dimensional measurement can add height information, but results still depend on board positioning, inspection programming and the feature under test. SAKI reports reduced false calls without publishing comparable false-rejection statistics for an identified production dataset.
An additional function examines the broader surface rather than restricting inspection to known component and joint positions. SAKI calls this Full Memory Technology and says it can detect solder balls as small as 200 micrometres as well as foreign object debris and unexpected components. A loose solder ball can cause an electrical short if it becomes trapped at a susceptible point. Detecting such material across the board addresses a different failure mode from assessing whether a planned solder joint meets dimensional acceptance criteria.
SAKI specifies a 15µm optical resolution for the inspection system, which describes the imaging arrangement rather than a guaranteed minimum detectable defect size. Detection depends on contrast, surface geometry, illumination and programmed criteria. Separately, SAKI claims that its Full Memory Technology detects solder balls down to 200µm; the two figures must not be treated as equivalent limits. Production acceptance trials remain necessary to assess performance on representative boards.
Inspecting the underside inline without turning the board over removes a mechanical handling step and may simplify line layout. The system is designed to accommodate tall or unusual through-hole components on the top side, with 140mm of top clearance and 35mm beneath the board. A high-rigidity conveyor supports the heavier fixtures that can be used during back-end assembly. These limits must be checked against component envelopes, pallets and edge-clearance requirements before the equipment can be inserted into a particular production line.
SAKI specifies board dimensions from 50 × 100mm to 510 × 510mm as standard. The two-step scan function permits boards up to 510 × 720mm; it does not extend the width beyond 510mm. Board mass is limited to 2kg on ordinary conveyor rails or 12kg with the weight-transfer conveyor option. Larger dimensions and heavier fixtures cannot be assumed to be compatible without selecting the relevant handling configuration.
The inspection machine measures 1,140 × 1,700 × 1,580mm and weighs approximately 980kg. Its listed electrical requirement is single-phase 200–240V at 50/60Hz, with a 650VA rating. SAKI also offers provision for an optional return conveyor beneath the machine. These specifications give integrators defined layout and service requirements but do not quantify cycle time for every board type, which will depend on scan coverage and programmed inspections.
The 3Di-LS3BX uses the same software environment as SAKI’s solder paste and post-reflow optical inspection systems. Inspection data can be generated from solder-mask Gerber information, reducing some initial programming work, while onboard diagnostics monitor machine status. Common software may assist operators moving between production stages, although settings and acceptance criteria still have to be established for the defects each station is supposed to identify.
SAKI previously previewed bottom-side inspection, while the October launch identifies the 3Di-LS3BX and its published operating limits. The manufacturer has not reported a named customer installation, independently measured yield improvement or universal cycle time. Assessment on the intended PCB mix will need to establish inspection coverage, handling compatibility, false-call behaviour and cycle time against the factory’s acceptance criteria.
