Nozzle Selection for Pick and Place

The Nozzle Is the Interface

The nozzle is the only part of a placement machine that touches the product, and it decides whether the component is picked reliably, held in the right orientation and placed without damage. A machine with an excellent vision system and a poor nozzle selection will still place badly, because the placement depends on a stable hold from the moment of pickup to the moment of release. Nozzle selection is therefore a process decision, and it should be recorded with the program rather than left to the operator’s preference.

Matching the Tip to the Component

The nozzle’s bore, its outer diameter and its contact face all matter. The bore must be smaller than the component’s top surface but large enough to provide the vacuum force required, and the tip’s outer diameter must fit between neighbouring components without touching them during placement. For a small passive the bore is tiny, the tip is delicate and the vacuum force is limited by the area; for a large connector the nozzle may have several bores or a broad contact face. Where the tip is too large, the nozzle cannot reach into a dense area; where it is too small, the vacuum force is insufficient and the component moves during the move.

Contact and the Placement Force

Two families of nozzle exist: those that place the component in contact with the board and those that release it from a small height. The contact type uses a mechanical stop and a defined force, which gives a consistent placement height, and it is used where the paste volume is controlled and the placement has to be repeatable. The non contact type releases the component without touching down, which avoids disturbing the paste on a small pad and is used for very small components and for fine pitch. The choice should match the component and the paste deposit rather than the machine’s default.

Vacuum and Its Limits

Vacuum holds the component, and its force is the pressure difference multiplied by the area it acts on. A component with a small top surface therefore provides little force, which makes the acceleration of the machine’s head a real constraint on small parts. A porous component, such as a bare die or a part with an open top, lets air through and reduces the force. Where the vacuum is marginal the component will rotate or slip during the move, and the defect appears as an offset placement or a rotated part that the vision system cannot correct. The vacuum level should be monitored, and the machine’s vacuum generation and filtration should be maintained.

Nozzle Faults and Their Symptoms

Nozzles wear and clog, and the symptoms are recognisable. A partially blocked bore reduces the vacuum and causes pick failures or dropped components. A worn tip loses its flatness and holds the component at an angle, which appears as a tilt after placement. A bent nozzle places components off centre in a consistent direction. A nozzle that has picked up adhesive from the tape or paste from a previous placement will not release cleanly, and the component ends up displaced. Cleanliness of the nozzle is one of the simplest maintenance items and one of the most commonly neglected.

Nozzle Changeover and Verification

Where a product uses several nozzle types, the changeover is a chance to make an error, and the machine will place components with whatever nozzle is fitted. The nozzle set for a product should be documented, the positions should be checked at the start of the run and the automatic nozzle changer should be verified against the program. A first article that checks placement and orientation catches a wrong nozzle; a vision system that corrects an offset will hide a nozzle problem until it reaches the limit of its correction. Recording which nozzle was used is part of the product’s process history.

Maintenance and Replacement

A nozzle is a consumable and should be treated as one. The tip should be inspected at magnification for wear and damage, the bore checked for blockage, and the nozzle cleaned with the method the manufacturer specifies. Where a nozzle is used heavily, a replacement schedule is more reliable than an inspection that depends on someone noticing. Ceramic and ruby tipped nozzles wear more slowly than those with a soft tip, and the choice should account for the component mix. The cost of a nozzle is small compared with the cost of the defects it causes when it is worn.

Matching the Nozzle to the Package

Beyond the simple size match, some package types need a specific approach. A chip scale package with a very small body may need a nozzle with a soft compliant tip so that the force is spread and the body is not cracked. A connector with a large body may need several nozzles placing it together, or a single nozzle with a broad face and a mechanical centring feature. A bare die needs a nozzle that does not touch the active surface. Where a component is supplied in a tray rather than a tape, the nozzle has to be able to retrieve it from the pocket without disturbing its neighbours, which is a different constraint from a taped part. Reviewing each package against the nozzle set is what prevents a repeated defect on one component.

FAQ

How is a nozzle chosen? By the component’s size and mass, the vacuum force required and the space available around the placement position.

What is the difference between contact and non contact placement? Contact presses to a defined height; non contact releases from a small gap, which suits fine pitch and small pads.

Why does a small part rotate in flight? The vacuum force is limited by the small contact area, so the head’s acceleration can move it.

What are the signs of a worn nozzle? Pick failures, consistent tilt or offset, and components that are not released cleanly.

How often should nozzles be replaced? On a schedule related to their usage, rather than relying on visual inspection alone.

Conclusion

The nozzle decides whether the component is held and released correctly, so match the tip to the part and record the set with the program. Clean and replace them as consumables. Placement control belongs to SMT PCB assembly, the assembly line that uses it sits within PCB assembly, and the verification of placement is part of quality management. Nozzle selection for a new product is set during prototype PCB assembly in 2026.