Training Material for SMT/DIP Jigs & Carriers

一. Reflow Soldering Pallet

1. The supporting edge of the pallet must be ≥ the width of the conveyor belt, typically 5mm or wider. The thickness of the supporting edge should not be excessive, generally between 1.5mm and 2mm.
2. The pallet must have large rounded corners on all four sides to prevent jamming during operation. The radius of the rounded corners is generally equal to the width of the supporting edge.
3. Wherever possible without compromising the pallet's structural strength, hollow out the central area where the PCB sits. This ensures the pallet is fully heated inside the reflow oven and prevents cold soldering.
4. For pallets used in printing and placement, the height of the locating pins must not exceed the surface height of the loaded PCB, as this would damage the stencil inside the printer.
5. The depth of the recess for the PCB must not exceed the thickness of the PCB, as this would increase the thickness of the printed solder paste, leading to post-reflow shorts.
6. Use only high-quality imported synthetic stone (Rouslin) for reflow pallets. Inferior materials will deform under prolonged heat exposure.
7. Use lock nuts when installing screws to prevent loosening.

二. Wave Soldering Pallet

1. The width of the supporting edge must be designed to accommodate the wave soldering machine's fingers, typically 5mm or wider. No structures should be present on the top surface of the supporting edge to avoid interference with the fingers. The thickness of the supporting edge is generally 2mm.
2. The pallet must have large rounded corners on all four sides to prevent jamming when entering the wave and during travel on the fingers. The radius of the rounded corners is generally equal to the width of the supporting edge.
3. The cutouts for component leads should be as large as possible, with wide-angle chamfers on the bottom side. This allows the solder wave to flow better into the cutouts. No additional cutouts should be made outside the soldering area to prevent solder leakage.
4. Solder dams must be installed around the entire perimeter, with full-length dams at the front and rear.
5. Use stainless steel screws for any fasteners exposed on the bottom of the pallet to prevent solder adhesion.
6. Large pallets or those with extensive cutouts that are prone to warping must be fitted with reinforcing ribs.
7. Include anti-float structures for components that tend to lift during soldering.

三. Aluminum Alloy Pallet

1. Use high-quality aluminum alloy material. Inferior alloys will deform permanently under heat and cannot be corrected.
2. Typically, only one side of the pallet is machined. Measures must be taken to prevent deformation during machining.
3. The flatness of the pallet must be corrected after machining, with a general requirement of 0.03mm.
4. For pallets requiring large hollowed-out areas, leave wider borders to ensure structural strength.
5. Control the depth of the PCB recess carefully. Generally, avoid over-cutting, as this causes excess solder paste printing and leads to shorts.
6. Ensure the positional and dimensional accuracy of the locating pins machined into the pallet: position tolerance of 0.01mm, and pin diameter 0.02mm smaller than the PCB holes.
7. Install the locating pins with an interference fit and secure them with high-temperature adhesive.
8. The pallet surface should undergo hard anodizing to enhance wear resistance.

四. Magnetic Pallet

1. The pallet body is made of aluminum alloy and must meet all the requirements for standard aluminum alloy pallets.
2. Access cutouts for PCB removal must not be located where components will be placed.
3. Machining tolerances for magnet mounting holes should be positive to prevent magnets from being too tight to fit.
4. Install magnets on a steel plate with consistent polarity. Take care not to break the magnets when tapping them into place.
5. After installation, apply red adhesive over the magnets to secure them. This ensures they remain magnetic even if fractured and prevents debris from falling out.
6. Cutouts in the 0.05mm magnetic steel sheet should not be too close to components, as this can cause excess solder paste printing.
7. Cutouts must be made in the magnetic steel sheet to expose the PCB's fiducial marks.
8. The fit between the base locating pins and the pallet must be smooth to prevent jamming during operation.

五. Silicone Pallet

1. The pallet body is made of aluminum alloy and must meet all the requirements for standard aluminum alloy pallets.
2. When designing the aluminum base, design it based on the product being placed directly on it.
3. Apply a uniform 1mm thick layer of silicone over the entire top surface of the machined pallet body.
4. Silicone pallets require dedicated fixtures to align and position the product on the pallet.
5. During use, the product must be placed flat and correctly aligned on the pallet.