TECHNICAL BULLETIN TB-3060 Full-Time Continuous Monitor Made in the Installation, Operation and Maintenance United States of America ADVANTAGES OF WORKSTATION CONTINOUS MONITORING OVER PERIODIC TESTING Many customers are eliminating periodic testing and are utilizing workstation continuous monitoring to better ensure that their products were manufactured in an ESD controlled environment. Full time workstation continuous monitoring is superior to pulsed monitoring as well as periodic testing, and can save a significant amount of money in testing costs and rejected products. Periodic testing detects failures after ESD susceptible products have been manufactured. The costs of dealing with the resulting catastrophic or latent defects can be considerable. Full Time Continuous Monitors eliminate the need for users to test wrist straps and log the results by their function, these monitors satisfy the ISO 9000 and ANSI/ESD S20.20 Paragraph 6.2.2.2. test logging requirements. Per ESD-S1.1 paragraph 6.1.3 Frequency Figure 1. Desco Full-Time Continuous Monitor of Functional Testing Daily (Wrist Strap) testing may be omitted if constant monitoring is used. Description Per ESD Handbook TR 20.20 paragraph 5.3.2.4.4 Test Leading companies use continuous monitors as a cost Frequency Because wrist straps have a finite life, it is effective component in satisfying the paragraph 6.1.3 important to develop a test frequency that will guarantee Compliance Verification Plan requirements of ANSI/ integrity of the system. Typical test programs recommend ESD S20.20. The Desco Full Time Continuous Monitor that wrist straps that are used daily should be tested daily. provides 100% monitoring of both the operator and the work However, if the products that are being produced are of surface. This unit provides continuous monitoring of: such value that knowledge of a continuous, reliable ground One user wearing a wrist strap is needed, and then continuous monitoring should be ESD worksurface considered or even required. Ground WAVE DISTORTION DETECTION TECHNOLOGY AC outlet PROVIDES TRUE 100% CONTINUOUS MONITORING Note: Worksurface must have a conductive layer such as Desco utilizes wave distortion technology for the Full Time Dual Layer Rubber, Dissipative 3-Layer Vinyl or Micastat Continuous Monitor, which is an Impedance type monitor. Dissipative Laminate with conductive buried layers. Desco Per ESD TR12-01 section 2.2 Impedance (or single wire) Continuous Monitors are not recommended for use with constant monitors The capacitance type of monitor is homogeneous matting. also known as an impedance monitor. They both work on If the unit detects that the elements are outside industry the same theory, however the impedance monitor uses standards, the continuous monitor will alarm woth both an a detection circuit designed to reduce false alarms and audible alarm and an illuminated red LED to notify the user eliminate adjustments. Single Wire or impedance type of a problem. monitors use the phase difference between current and voltage to detect changes in impedance of the cord, band Unlike many units, the Full Time Continuous Monitor also and person. A very low AC voltage is used for constant continuously verifies ground (AC outlet ground). When the sensing. Any standard wristband and coiled cord can be Power Cord is plugged in, a self-test runs automatically. used. If the AC outlet is wired incorrectly, both red LEDs will illuminate and the audible alarm will sound. The unit has an Thus the wave distortion circuitry monitors current/voltage additional ground point for a user or supervisor. phase shifts and provides true 100% continuous monitoring. Electrical current will lead voltage at various points due to The Full Time Continuous Monitor is available in two the combinations of resistance and capacitive reactance. models: By monitoring these distortions or phase shifts, the wave distortion Full Time Continuous Monitor will reliably determine Item Input Voltage Power Cord if the circuit is complete. 19325 120VAC North America 19326 220VAC United Kingdom DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Website: Desco.com 2019 DESCO INDUSTRIES INC TB-3060 Page 1 of 5 May 2019 Employee OwnedWave distortion technology can be referred to as vector Packaging impedance monitoring. This description is valid as the 1 Full-Time Continuous Monitor wave distortion technology measures the impedance at the 1 Power Cord monitored banana jack and looks for changes in either the 1 Mat Monitor Cord (Black) capacitance or resistance of the circuit which includes the 1 Ground Cord (Green and Yellow) wrist strap and its wearer. It uses filtering and time domain 2 Countersunk Washers sampling to filter out false signals caused by voltage offsets, 2 Flat Head Screws, 6-32 x 1/4 60 Hz fields and other electro-magnetic and electrostatic 1 Hook and Loop Fastener Strip interference. 1 Certificate of Calibration In normal factory environments, and with persons whose Features and Components capacitance with respect to ground is within design limits (5 feet tall 90 pound person to 6 foot 5 inch 250 pound person), B C D A the Full Time Continuous Monitor cannot be fooled. It will provide a reliable alarm only when the wrist strap or work surface becomes dysfunctional or unsafe according to accepted industry standards. The Full Time Continuous Monitor is drift-free and designed to be insensitive to the effects of squeezing or stretching the coil cord. E ADVANTAGES OF WAVE DISTORTION AND SINGLE-WIRE TECHNOLOGY The Desco Full Time Continuous Monitor allows the use F of any standard, single-wire wrist strap and coil cord. The monitor / wrist strap / cord system life-cycle costs are by far lower than alternative systems which require dual-wire cords and special wrist straps. Dual-wire cords are expensive and are the weak link of the system, the most likely component to need replacement. Over a five year period, this can make the dual-wire system three to five times as expensive as G H I a system utilizing single-wire wrist straps and cords. See Calibration section on page 4 to minimize life cycle costs. Figure 2. Full-Time Continuous Monitor features and components The dictionary defines constant as uniform and unchanging, and continuous as uninterrupted. None theless, some A. IEC Power Cord Inlet: Connect the power cord here. dual-wire resistance monitors utilize a pulsed test current and do not really provide continuous monitoring. For example, B. I/O Signal Output: Contact Desco Customer Service for during each 2.2 second pulse cycle of a leading constant more information resistive monitor, electrical current is pulsed for only 0.2 C. Monitored Ground Terminal: Grounds the worksurface seconds followed by an unmonitored interval of 2 seconds. mat. Connect the green and yellow ground cord here. This leaves the user/wrist strap unmonitored for over 90% of each cycle. Damaging static charges can easily occur in the D. Monitored Mat Terminal: Monitors the worksurface mat. portion of the time in between the pulses. The off period of Connect the black mat monitor cord here. 2 seconds equals 2 billion nanoseconds, and it takes only about 25 volts applied for 100 nanoseconds to blow most E. Mat Ground LEDs: When the green LED is illuminated, memories or microprocessors.* Some dual-wire systems do the worksurface mat is properly grounded. When the red not reliably meet all industry specifications, as the cords may LED is illuminated and the alarm sounds, the worksurface not meet the EOS/ESD S-1.0 paragraph 4.1.6 one to five mat is not properly grounded. pound breakaway force requirement for operator safety. F. Operator Ground LEDs: When the green LED is By using the reliable wave distortion technology to determine illuminated, the operator is properly grounded. When the if the circuit is complete, there are no false alarms. There red LED is illuminated and the alarm sounds, the operator is no need to adjust or tune the monitor to a specific user is not properly grounded. or installation. The miniscule amount of electrical current G. Auxiliary Ground: Unmonitored banana jack ground (less than 1 volt coil cord signal) required to generate the point. waveform has never caused reported skin irritation and is extremely safe for use in voltage sensitive applications such as disk drive manufacturing. DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Website: Desco.com 2019 DESCO INDUSTRIES INC TB-3060 Page 2 of 5 Employee Owned