Philips Semiconductors Handling MOS devices General The devices should be kept in their original packing whilst in storage. If a bulk container is partially unpacked, the unpacking should be performed at a protected work station. Any devices that are stored temporarily should be packed in conductive or antistatic packing or carriers. HANDLING MOS DEVICES(1) Electrostatic charges Electrostatic charges can exist in many things; for example, man-made-fibre clothing, moving machinery, objects with air blowing across them, plastic storage bins, sheets of paper stored in plastic envelopes, paper from electrostatic copying machines, and people. The charges are caused by friction between two surfaces, at least one of which is non-conductive. The magnitude and polarity of the charges depend on the different affinities for electrons of the two materials rubbing together, the friction force and the humidity of the surrounding air. Assembly The devices must be removed from their protective packing with earthed component pincers or short-circuit clips. Short-circuit clips must remain in place during mounting, soldering and cleansing/drying processes. Do not remove more devices from the storage packing than are needed at any one time. Production/assembly documents should state that the product contains electrostatic sensitive devices and that special precautions need to be taken. Electrostatic discharge is the transfer of an electrostatic charge between bodies at different potentials and occurs with direct contact or when induced by an electrostatic field. Our devices can be damaged if the following precautions are not taken. All tools used during assembly, including soldering tools and solder baths, must be earthed. All hand tools should be of conductive or antistatic material and, where possible, should not be insulated. Work station Figure 1 shows a working area suitable for safely handling electrostatic sensitive devices. It has a work bench, the surface of which is conductive or covered by an antistatic sheet. Typical resistivity for the bench surface is between 1 and 500 k per cm2. The floor should also be covered with antistatic material. Measuring and testing of completed circuit boards must be done at a protected work station. Place the soldered side of the circuit board on conductive or antistatic foam and remove the short-circuit clips. Remove the circuit board from the foam, holding the board only at the edges. Make sure the circuit board does not touch the conductive surface of the work bench. After testing, replace the circuit board on the conductive foam to await packing. The following precautions should be observed: * Persons at a work bench should be earthed via a wrist strap and a resistor. Assembled circuit boards should be handled in the same way as unmounted devices. They should also carry warning labels and be packed in conductive or antistatic packing. * All mains-powered electrical equipment should be connected via an earth leakage switch. * Equipment cases should be earthed. * Relative humidity should be maintained between 50 and 65%. * An ionizer should be used to neutralize objects with immobile static charges. Receipt and storage Our devices are packed for dispatch in antistatic/conductive containers, usually boxes, tubes or blister tape. The fact that the contents are sensitive to electrostatic discharge is shown by warning labels on both primary and secondary packing. (1) These products are supplied in anti-static packing to prevent damage caused by electrostatic discharge during transport and handling. For further information, refer to Philips specs.: SNW-EQ-608, SNW-FQ-302A and SNW-FQ-302B. 1999 May 17 1 Philips Semiconductors Handling MOS devices General (1) handbook, full pagewidth (2) (2) (2) (3) (7) (6) (8) (5) (4) ,,,,,,,,,, (9) (1) (2) (3) (4) (5) (6) (7) (8) (9) Earthing rail. Resistor (500 k 10%, 0.5 W). Ionizer. Work bench. Chair. Wrist strap. Electrical equipment. Conductive surface/antistatic sheet. Antistatic floor. Fig.1 Protected work station. 1999 May 17 2 MLB049