RoHS: How the Changing Regulatory Landscape is Affecting the Disk Drive Industry Henri C.H. Seng Business Manager, Asia Pacific Henry Yu China Sales Manager
Introduction In 1998, the European Union (EU) discovered that alarmingly large amounts of hazardous waste were being dumped into landfill sites. To address hazardous waste issues, the member states of the EU created the Waste Electrical and Electronics Equipment (WEEE) directive. The WEEE directive laid the groundwork for additional legislation and a proposal called Environment of Electrical & Electronics Equipment (EEE).
EU directive 22/95/EC The Restriction of the use certain Hazardous Substances in electrical and electronic equipment or RoHS was implemented in July 26. Restricts the use of hazardous substances in electrical and electronic equipment. Lead (Pb) Mercury (Hg) Hexavalent chromium (Cr(VI)) Cadmium (Cd) Polybrominated biphenyls (PBB) Polybrominated diphenyl ethers (PBDE).
Where is RoHS in Effect? All EU member countries. Croatia, Norway, and Switzerland may have similar legislation. China RoHS regulations are also in effect. Many consider them to be considerably more restrictive. Argentina, Australia, Brazil, Japan, Korea, Taiwan, Thailand, and the United States have passed or have pending RoHS legislation.
Get the Lead Out! An aim shared by almost all RoHS legislation is the elimination of lead in electronic products. Printed circuit boards (PCBs) have conducting layers on their surface typically made of thin copper foil. Traditionally, any exposed copper was plated with lead(-based) solder.
Lead-Free Transition One failure mechanism was not foreseen by the industry, i.e., lead-free products with a silver surface finish will corrode in high sulfur environments. ISA Class G2 or higher. The majority of failures occurred on hard disk drives (HDD), graphic cards, and motherboards. Corrosion failures have increased dramatically. The most common failures are with the most common components.
RoHS Corrosion Studies None of the coatings can be considered immune from failure in an ISA Class G3 environment. Printed circuit boards made using lead-free materials can be more susceptible to corrosion than their tin/lead counterparts.
Causes of Corrosion Corrosion can be defined as the deterioration of a substance (usually a metal) because of a reaction with it s environment. Corrosion of metals is a chemical reaction caused primarily by the attack of gaseous contaminants and is accelerated by heat and moisture. Rapid shifts in either temperature or humidity cause small portions of circuits to fall below the dew point temperature, and facilitate condensation of contaminants.
Example of creep corrosion caused by sulfur contamination causing a short circuit on a PCB.
Corrosion and Air Quality The International Society for Automation (ISA) Standard 71.4 classifies several levels of environmental severity for electrical and electronic systems: G1, G2, G3 and GX, which provides a measure of the corrosion potential of an environment. G1 is benign and GX is openended and the most severe.
Classification of Reactive Environments Class Severity Level Copper Reactivity Comments G1 Mild <3Å An environment sufficiently well-controlled such that corrosion is not a factor in determining equipment reliability. G2 Moderate <1Å An environment in which the effects of corrosion are measurable and corrosion may be a factor in determining equipment reliability. G3 Harsh <2Å An environment is which there is a high probability that corrosive attack will occur. These harsh levels should prompt further evaluation resulting in environmental controls or specially designed and packaged equipment. GX Severe 2Å An environment in which only specially designed & packaged equipment would be expected to survive. Specifications for equipment in this class are a matter of negotiation between user & supplier.
Measuring Corrosion Reactivity Monitoring Involves placement of specially prepared metal coupons / sensors in the local environment. Analysis may measure film thickness, film chemistry, and/or weight loss. ISA Standard references measurement of film thickness by cathodic (electrolytic) reduction. ALLOWS FOR DIRECT CORRELATION BETWEEN CORROSION AND RELIABILITY.
Measuring Corrosion (2) Copper AND silver monitoring is required for complete environmental analysis. Corrosion on copper is humidity dependent. Silver corrosion can be attributed solely to chemical contaminants. Silver can identify the presence of inorganic chlorine. Silver is more sensitive to low levels of contaminants.
Real-Time Corrosion Monitoring Atmospheric Corrosion Monitor (ACM) Microprocessor-controlled device that continuously monitors corrosion caused by pollutant gases. Can be operated as a battery-operated data logging system or wired into a central computer system. Can also monitor temperature and RH.
Corrosive Gases Active sulfur compounds (H 2 S) Sulfur oxides (SO 2, SO 3 ) Nitrogen oxides (NO X ) Inorganic chlorine compounds (Cl 2, ClO 2, HCl) Hydrogen fluoride (HF) Ammonia and derivatives (NH 3, NH 4+ ) Photochemical species (O 3 ) Strong oxidants
Nitrogen Dioxide Levels in Asia Motor vehicles cause 54% of all urban air pollution. Air monitoring shows that metropolitan areas do not meet national standards for fine particles (PM 2.5 ) and ozone (O 3 ). 16
Air Quality in Thailand vs. ISA Standard Air Quality Index for Bangkok SO 2 : NO 2 : O 3 : 1 17 ppb, 8.3 ppb (avg.) G1 (<1 ppb) Avg.: G1 1 15 ppb, 63.5 ppb (avg.) G1 (<5 ppb) Avg.: G2 1 17 ppb, 16.39 ppb (avg.) G1 (<2 ppb) Avg.: G2 Although contaminant concentrations may suggest an ISA Class G1 or G2 severity level, the synergistic effects of these contaminants would most likely produce an ISA Class G3 or GX severity level.
Air Quality in China vs. ISA Standard Air Pollution Indices for China Beijing SO 2 : 22 67 ppb G1 (<1 ppb) G1/G2G2 NO 2 : 44 73 ppb G1 (<5 ppb) G1 O 3 : 5 12 ppb G1 (<2 ppb) G3/GX Shanghai SO 2 : 2 3 ppb G1 (<1 ppb) G1/G2G2 NO 2 : 65 66 ppb G1 (<5 ppb) G1 O 3 : 1 16 ppb G1 (<2 ppb) GX Although individual contaminant concentrations may suggest an ISA Class G1 or G2 severity level, the synergistic effects of these contaminants will most likely produce an ISA Class G3 or GX severity level.
CCC Results for Asian Data Centers Copper Corrosion Silver Corrosion Type Location Cu 2 S Cu 2 O Cu-Unk Total ISA Level AgCl Ag 2 S Ag-Unk Total Bank Inside DC 75 75 G1 636 636 Financial Services Server Room 122 7 192 G1 524 524 Call Center Inside DC 162 15 267 G1 982 982 Bank Inside DC 193 94 287 G1 785 785 Bank DC supply air 288 288 G1 23 227 25 Bank Under raised floor 258 89 347 G2 1,47 1,47 Bank Data storage 265 91 356 G2 3,2 3,2 Company HQ Inside DC 299 8 379 G2 1,63 1,63 Bank Inside DC 334 75 49 G2 1,833 1,833 Financial Services Inside DC 29 24 449 G2 16 16 Financial Services Outside air 355 137 492 G2 135 353 488 Bank DC supply air 426 85 511 G2 861 861 Bank Inside DC 415 179 594 G2 1,122 1,122 Call Center Server room 474 143 617 G2 852 852 Bank Under raised floor 587 18 767 G2 45 1,742 1,787 Every data center shown here had documented hardware failures due to sulfur corrosion even though they met the manufacturer s recommended ISA Severity Level.
Data Center (DC) Case Study HDD Errors 1. Assessment of the power grid, specifically on the power feeding the disk array. 2. Verify air quality in the data center including information on: a. Data center ventilation, temperature, humidity levels, air conditioning systems, air cleaning systems. b. Data center/site location (near factories, coal burning power plants, highways, etc.) c. Visual inspection (with magnifier) of the PCBs of the failed HDDs. Signs of corrosion should be visible around solder joints, vias, IC legs, etc. 3. Keep all of the HDDs that show any signs of corrosion. a. If customer does not meet the specified requirements for the data environment they will void the warranty and support contract. Division will not be responsible to support the array if the warranty is voided.
DC Case Study HDD Status Report 1. HDDR-1 GROUP: 1-2 Device Status: Failed Port Status: Failed 2. HDDR-4 GROUP: 1-5 Device Status: Blocked Port Status: Normal 3. HDDR-9 GROUP: Spare Device Status: Failed Port Status: Failed 4. HDDR1-1 GROUP: 1-2 Device Status: Failed Port Status: Normal 5. HDDR1-4 GROUP: 1-5 Device Status: Failed Port Status: Normal 6. HDDR1-5 GROUP: 1-6 Device Status: Failed Port Status: Normal 7. HDDR4-19 GROUP: Spare Device Status: Failed Port Status: Normal 8. HDDR2- GROUP: 1-1 Device Status: Failed Port Status: Normal 9. HDDR2-7 GROUP: 1-8 Device Status: Failed Port Status: Normal 1. HDDR3-E GROUP: 1-16 Device Status: Failed Port Status: Failed 11. HDDR6-13 GROUP: 2-4 Device Status: Warning Port Status: Warning port 1 failed 12. HDDR6-17 GROUP: 1-8 Device Status: Failed Port Status: Normal 13. HDDR1- GROUP: 3-1 Device Status: Failed Port Status: Normal 14. HDDR11- GROUP: 3-1 Device Status: Failed Port Status: Normal 15. HDDR16-1 GROUP: 3-2 Device Status: Failed Port Status: Normal
DC Case Study Response to HDD Errors Report from Sr. System Engineer: There is no cleaning that the local team can do to remove any sulfur contamination from the disk array. It is the result of a chemical reaction between sulfur dioxide and water producing an acid that reacts between the silver and copper metals used in the manufacture of the electronic components. Response from hardware supplier: Management has decided to provide new 36 array (144) disk drives.
Disk Drive Failures and RoHS Increased incidents of corrosion can be attributed to: 1. Dominant use of surface finishes compatible with fine pitch soldering. Driven by increasing device / electronic package density needs which in turn has been driven by system performance requirements. The introduction of thin solderable surface finishes is perhaps one of the main factors associated with higher instances of corrosion. 2. Installation and use of products in expanding markets. Non-traditional IT environments where extremes of temperature, humidity, and airborne (gaseous and solid form) pollutants exist. Cost pressures have reduced the levels of environmental controls provided at the system and subsystem level. Field replaceable units, such as disk drives, are more likely to be exposed to harsh indoor environments than in the past.
DC Environmental Control The control of gaseous contaminants is critical in providing a truly "clean" data center environment. Gaseous contaminant control can be achieved by using chemical filtration systems employing one or more chemical filtration media. Packed-bed gas-phase air filtration systems are commonly used in fresh air systems. Extruded carbon composites, adsorbent-loaded fiber filters and combination particulate/chemical filters are also being used.
DC Design Considerations Basic Room Air Pressurization Pressurize the room to.5-.1 IWG (12.5 25. Pa) with clean air (3 to 6 air changes per hour) Humidity Control <5% Relative Humidity (with less than a 6% change per hour) Temperature Control 7± 2 F (21 ± 1 C) Room Construction and Integrity Well-sealed room; double airlock entryways Room Air Recirculation 6 to 12 air changes per hour
DC Design Considerations Advanced Gaseous contamination control Makeup (Outdoor, Fresh) Air Handlers Air-Side Economizers Computer Room Air Conditioning (CRAC) Units Recirculating Air Handlers (CA Unit) Positive Pressurization Unit (PPU) Under-Floor Air Filtration Filtration effectiveness and filter life Particulate contamination monitoring ΔP Gaseous contamination monitoring CCCs, real-time corrosion monitors
ASHRAE Contamination Guidelines* Data centers must be kept clean to ISO 14644-1 Class 8. The room air may be continuously filtered with MERV 8 (3%, G4) filters. Air entering a data center may be filtered with MERV 11-13 (95%, FF8) filters. Sources of dust inside data centers should be reduced. Every effort should be made to filter out dust that has deliquescent relative humidity greater than the maximum allowable relative humidity in the data center. *Gaseous and Particulate Contamination Guidelines for Data Centers (29)
ASHRAE Contamination Guidelines (2) Gaseous contamination should be within the modified ANSI/ISA-71.4-1985 severity level of G1- Mild that meets: A copper reactivity rate of less than 3 angstroms (Å) per month, and A silver reactivity rate of less than 3 Å per month. For data centers with higher gaseous contamination levels, gas-phase filtration of the inlet air and the air in the data center is highly recommended.
RoHS and Reliability The requirement for corrosion control in data center environments is constant and growing. RoHS has been an integral, but arguably unnecessary part of this transition. More companies are developing or updating specifications due to the changes made by controls manufacturers to comply with RoHS regulations. With many manufacturers using silver on their PCBs and other electrical components, and with silver (and copper) being much more sensitive to corrosion, we have seen increased concerns over equipment reliability.
Summary Computer systems and components used in data centers are protected against fire, power, shock, humidity, temperature and particulate contamination. Unfortunately, the potential damage to equipment caused by corrosion from gaseous contaminants due to RoHS compliance has not been fully recognized or addressed. Manufacturers have to comply with RoHS if they want to continue to do business in the EU, China, etc.
Summary (2) Recognizing the severity of the problem, the world's leading manufacturers of computer systems have jointly published a white paper titled, Particulate and Gaseous Contamination Guidelines for Data Centers*, that summarizes acceptable levels of data center contamination. Recent Journal Articles (India, China, U.S.A.) Part 1: Gaseous and Particulate Contamination Limits for Data Centers (ASHRAE TC 9.9) Part 2: Controlling Gaseous and Particulate Contamination in Data Centers (Purafil, Inc.) ASHRAE TC 9.9 (29)
Summary (3) Enhanced air filtration systems for data centers should be designed to ASHRAE guidelines. With the increasing pressure to reduce energy consumption in data centers, and the increasing use of air-side economizers, data centers located in regions with poor ambient air quality will struggle to maintain efficient operations without the application of enhanced air cleaning. The problem needs to be addressed by monitoring of the environment and removal of contaminants where needed.
Conclusions Assuring long-term equipment reliability requires: Quantifying the corrosive potential of an environment. Providing engineered solutions for gaseous and particulate contaminant control. Ongoing monitoring of the controlled environment. The successful application of such an environmental control program will protect critical electronic equipment and assure continuous and profitable operations.
Conclusions (2) The issue and potential for corrosion-related problems in data centers is acknowledged. Data from many different sites shows that corrosive atmospheres exist in locations that most would consider otherwise benign if not for the changes in electronics mandated by RoHS legislation. These problems can be addressed by continuous monitoring of the data center environment and removal and control of corrosive contaminants where indicated.
Conclusions (3) Ultimately, the successful implementation of a corrosion protection program requires: 1. Knowledge and understanding that corrosion of electronic equipment is a serious problem. 2. Commitment to a monitoring program to describe the potential for electronic equipment failure. 3. Commitment to an integrated contamination control system. 4. Commitment to take corrective action whenever necessary.
Thank You For Your Time. Any Questions? Contact Information: Henri Seng, hseng@purafil.com Henry Yu, hyu@purafil.com