ESD Control.docx

1、ESD Control ConfidentialPeople Committed To InfoTechESD CONTROL PROGRAMREVISION : ADate:11/9/1999Prepared By:_Gyver LoApproved By:_ W.C.WangMITAC INTERNATIONAL CORP.TAIPEI OFFICE : 8TH FL., NO.75, MING SHENG E. RD., SEC.3, TAIPEI, TAIWAN, R.O.C. TEL:886-2-5018231 TELEX:11942 TAIAUTO FAX:886-2-501426

2、5FACTORY:1,R&D ROAD 2. HSINCHU SCIENCE-BASED INDUSTRIAL PARK, HSINCHU, TAIWAN, R.O.C. TEL:886-35-779250 FAX:886-35-776209DOCUMENT CHANGE STATUSREVCHANGE DESCRIPTIONPREPAREDAPPROVEDAFirst ReleaseGYVER LOW.C.WANGContents 1 ABSTRACT 42 REFERENCES 53 PROBLEM STATEMENT 64 TEAM STRUCTURE AND MEMBER LIST 7

3、5 ESD PROTECTION EQUIPMENT 96 MEASURING EQUIPMENT 147 ESD CONTROL CHECKING ITEMS 168 ESD CONTROL TRAINING PROGRAM 219 AUDITING PROGRAM 23 1 ABSTRACT This ESD Control Program establishes the minimum requirements for Electrostatic Discharge (ESD) control methods and materials used to protect electroni

4、c devices that are susceptible to damage or degradation from ESD. The passage of a static charge through an electrostatic- discharge-sensitive (ESDS) device can result in catastrophic failure or performance degradation of the part. In the following sections, we implement several ESD protective equip

5、ment and some measuring equipment to maintain their functions. Also we implement ESD control training program and ESD audit program to strengthen and check our execution of ESD Control Program. However, the effectiveness should be relied on exact implementation and prompt corrective actions.2 REFERE

6、NCES 2.1 Workmanship Specification for ESD Control Document, A-5951-1589-1, Revision H, ESD Program, HP Corporate, 1999. 2.2 Requirements for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices, EIA-625, EIA Standard, EIA, 1994. 2.3 Basics of Electrostatic Discharge, ESD Association, 1998. 2.4

7、 Protection Against Electrostatic Damage, Sharp, 1995. 2.5 ESD/EOS Fundamental and Avoidance, INTEL, 1996. 2.6 靜電防制專業工程師訓練課程講義，工業技術研究院電子所，1999. 3 PROBLEM STATEMENTAccording to Stephen Halperin (Guidelines for Static Control Management, Eurostat 1990), average product losses due to static range from

8、8% to 33% (see Table 1). Others estimate the actual cost of ESD damage to the electronics industry as running into the billions of dollars annually. The cost of damaged devices themselves ranges from only a few dollars for a simple diode to several thousand dollars for complex hybrids. When associat

9、ed costs of repair and rework, shipping, labor, and overhead are included, clearly the opportunities exist for significant improvements.ESD damage to electronic components and assemblies has been a major problem of the electronics industry in recent years, or installing ESD sensitive devices. Device

10、s that arent destroyed during handling are often damaged or impaired. This damage is known as latent damage and often is not detectable by routine quality tests, and could appear after the device is installed in its host equipment.An electrostatic charge also may be created on a material in other wa

11、ys such as by induction, ion bombardment, photoelectric effect, particle beam, freezing, radioactive decay, spray, field emission or contact with another charged object. However, triboelectric charging is the most common. Table 2 shows some examples that can generate different voltage levels of elec

12、trostatic charges. Table 1Informal Summary ofStatic Losses by LevelStatic Losses ReportedDescriptionMinLossMaxLossEst. Avg.LossComponentManufacturers4%97%16-22%Subcontractors3%70%9-15%Contractors2%35%8-14%Users5%70%27-33%Source: Stephen Halperin. Guidelines for Static Control Management Eurostat 199

13、0. Table 2Examples of Static GenerationTypical Voltage LevelsMeans of Generation10-25% RH65-90% RHWalking across carpet35,000V1,500VWalking across vinyl tile12,000V250VWorker at bench6,000V100VPoly bag picked up from bench20,000V1,200VChair with urethane foam18,000V1,500V4 TEAM STRUCTURE AND MEMBER

14、LIST 4.1 Structure 4.2 Member ListPosition/Department Mission Chairman/QA Responsible for MiTACs ESD control programCoordinator/QE Develop, implement and maintain ESD control programAudit Controller/IPQA Responsible for the auditing programIQC Responsible for IQCs ESD control programSMT line Respons

15、ible for SMTs ESD control programPCBA production line Responsible for PCBA production lines ESD control programSystem assembly line Responsible for System assembly lines ESD control programWarehouse Responsible for Warehouses ESD control programOQA Responsible for OQAs ESD control programMOD Respons

16、ible for MODs ESD control programEngineering Division Assist the production line to execute and maintain the ESD control program 4.3 Schedule of Team Meetings 4.3.1 The first ESD Control meeting will be held at 10:10 AM, Friday, 5 Nov 99. 4.3.2 The second meeting will be held on Thursday, Dec 9, 199

17、9. 4.3.3 The third meeting will be held on Thursday, Jan 6, 2000. 4.3.4 Afterwards, meetings shall be held quarterly.5 ESD PROTECTION EQUIPMENT 5.1 ESD Wrist Straps and Gloves Typically, the primary means of controlling static charge on personnel is with a wrist strap and a pair of gloves. When prop

18、erly worn and connected to ground, a wrist strap keeps the person wearing it near ground potential. Because the person and other grounded objects in the work area are at or near the same potential, there can be no hazardous discharge between them. In addition, static charges are safely dissipated fr

19、om the person to ground and do not accumulate. Wrist straps have two major components, the cuff that goes around the persons wrist and the ground cord that connects the cuff to the common point ground. Most wrist straps have a current limiting resistor molded into the ground cord head on the end tha

20、t connects to the cuff. The resistor most commonly used is a 1M, 1/4W with a working voltage rating of 250 V. The resistance from a wrist strap wearers hand to ground shall be . 5.2 Shoes, Heel Straps Used in combination with ESD protective floor materials, static control shoes, grounders, casters a

21、nd wheels provide the necessary electrical contact between the person or object and the floor material. Insulative footwear, casters or wheels prevent static charges from flowing from the body to the floor to ground. The resistance from fingertip to ground is the same as wrist strap. 5.3 Smocks Clot

22、hing materials can generate electrostatic charges when they contact and separate from other objects and the clothing itself. These charges may discharge into sensitive components or create electrostatic fields that may induce charges on the human body.Although a person may be grounded, that does not

23、 mean that insulative clothing fabrics can dissipate a charge to that persons skin and then to ground. Clothing usually is electrically insulated or isolated from the body. Static control garments are intended to minimize the effects of electrostatic fields or charges that may be present on a person

24、s clothing. Smocks sleeve to sleeve resistance should be between and after 20 washings. 5.4 Work Stations and Work surfaces Work surfaces and work stations are important parts of an ESD protective program. Many ESDS devices and assemblies are handled, assembled or repaired at work stations. The work

25、 station provides a means for connecting all work surfaces, fixtures, handling equipment, and grounding devices to a common point ground. The key ESD control elements comprising most workstations are a static dissipative work surface, a means of grounding personnel (usually a wrist strap), a common

26、grounding connection, and appropriate signage and labeling. Static protective worksurfaces with a resistance to ground of to provide a surface that is at the same electrical potential as other ESD protective items in the workstation. They also provide an electrical path to ground for the controlled

27、dissipation of any static potentials on materials that contact the surface. The work surface also helps define a specific work area in which ESD sensitive devices may be safely handled. The worksurface is connected to the common point ground. 5.5 ESD Dissipative Chairs ESD chairs shall be constructe

28、d of static dissipative materials. The resistance from the seat cushion, back or arm rests to ground shall continuously be within the required range of to . 5.6 Ionizers As we have seen, the primary method of static charge control is direct connection to ground for conductors, static dissipative mat

29、erials, and personnel. However, a complete static control program must also deal with isolated conductors that cannot be grounded, insulating materials (e.g., most common plastics). Topical antistats often are used to dissipate static charges from these items under some circumstances. More frequentl

30、y, however, air ionization can neutralize the static charge on insulated and isolated objects by charging the molecules of the gases of the surrounding air. Whatever static charge present on objects in the work environment will be neutralized by attracting opposite polarity charges from the air. Because it uses only the air that is already present in the work environment, air ionization may be employed even in clean rooms where chemical sprays and some static dissipative materials are not usable. Air ionization is not a replacement for grounding methods. It is one component of