NICHIA STS-DA1-1555A <Cat.No.110318> NICHIA CORPORATION SPECIFICATIONS FOR GREEN LED NESG064T ● Pb-free Reflow Soldering Application ● Built-in ESD Protection Device ● RoHS Compliant NICHIA STS-DA1-1555A <Cat.No.110318> SPECIFICATIONS (1) Absolute Maximum Ratings Symbol Absolute Maximum Rating Unit Forward Current Item IF 30 mA Pulse Forward Current IFP 100 mA Allowable Reverse Current IR 85 mA Power Dissipation PD 105 mW Operating Temperature Topr -40~110 °C Storage Temperature Tstg -40~110 °C Junction Temperature TJ 125 °C * Absolute Maximum Ratings at TA=25°C. * IFP conditions with pulse width ≤10ms and duty cycle ≤10%. (2) Initial Electrical/Optical Characteristics Symbol Condition Typ Unit Forward Voltage Item VF IF=20mA 3.1 V Luminous Intensity1 Iv IF=20mA 870 mcd Iv IF=30mA 1130 mcd - IF=20mA 0.17 - Luminous Intensity2 Chromaticity Coordinate x - IF=20mA 0.70 - Thermal Resistance y RθJS - 180 °C/W Thermal Resistance RθJA - 360 °C/W * Characteristics at TA=25°C. * The Chromaticity Coordinates are derived from the CIE 1931 Chromaticity Diagram. * RθJS is Thermal Resistance from junction to TS measuring point. * RθJA is Thermal Resistance from junction to ambient（Test board: FR4 board thickness=1.6mm, copper layer thickness=35µm）. 1 NICHIA STS-DA1-1555A <Cat.No.110318> RANKS Item Forward Voltage Luminous Intensity Rank Min Max Unit V - 2.7 3.5 V 1120 1560 U 780 1120 T 560 780 mcd Color Ranks Rank G Rank H x 0.14 0.14 0.22 0.22 x 0.21 0.21 0.28 0.28 y 0.64 0.74 0.74 0.64 y 0.65 0.73 0.73 0.65 * Ranking at TA=25°C. * Tolerance of measurements of the Forward Voltage is ±3%. * Tolerance of measurements of the Luminous Intensity is ±10%. * Tolerance of measurements of the Chromaticity Coordinate is ±0.01. * Basically, a shipment shall consist of the LEDs of a combination of the above ranks. The percentage of each rank in the shipment shall be determined by Nichia. 2 NICHIA STS-DA1-1555A <Cat.No.110318> CHROMATICITY DIAGRAM 0.80 535 540 0.75 545 0.70 550 H y G 555 0.65 0.60 0.55 0.10 0.15 0.20 0.25 0.30 0.35 x 3 NICHIA STS-DA1-1555A <Cat.No.110318> OUTLINE DIMENSIONS * 本製品はRoHS指令に適合しております。 This product complies with RoHS Directive. NESx064 STS-DA7-0429 管理番号 No. Cathode Mark 2.2 (1.05) 2.8 (2.4) (0.45) (単位 Unit:±0.2) mm) (単位 Unit: mm, 公差 Tolerance: (0.8) (2.4) 2±0.3 (0.4) 3.2 0.8±0.3 (1.9) 0.8±0.3 3.5±0.3 Anode Cathode K 項目 Item 内容 Description パッケージ材質 Package Materials 耐熱性ポリマー Heat-Resistant Polymer 封止樹脂材質 Encapsulating Resin Materials シリコーン樹脂(拡散剤入り） Silicone Resin(with diffuser) 電極材質 Electrodes Materials 銅合金+銀メッキ Ag-plated Copper Alloy 質量 Weight 0.037g(TYP) A 保護素子 Protection Device 4 NICHIA STS-DA1-1555A <Cat.No.110318> SOLDERING • Recommended Reflow Soldering Condition(Lead-free Solder) 1 to 5°C per sec • Recommended Manual Soldering Condition 260°C Max 10sec Max Pre-heat 180 to 200°C Temperature 350°C Max Soldering Time 3sec Max 60sec Max Above 220°C 120sec Max ● Recommended Soldering Pad Pattern 9.5 4 4 4 1.5 2.6 1.5 (単位 Unit: mm) Blank boxes: Solder resist opening , Shaded areas: Footprint * The product is designed to be reflow soldered to a PCB. If you use dip soldering for the products, Nichia cannot guarantee its reliability. * Reflow soldering must not be performed more than twice. Manual soldering must only be done once. * Care should be taken to avoid cooling at a rapid rate and ensure the peak temperature ramps down slowly. * Customer is advised to use nitrogen reflow soldering as air flow process can cause optical degradation due to the heat and atmosphere of reflow soldering. * Since silicone used as encapsulating resin in this product is a soft material, do not press on the encapsulant. Failure to comply might lead to nicks, chip-outs, delamination and deformation of the encapsulant, wire breakage and an adverse effect on product reliability. * Repairing should not be done after the LEDs have been soldered. When repairing is unavoidable, a double-head soldering iron should be used. It should be confirmed beforehand whether the characteristics of the LEDs will or will not be damaged by repairing. * When soldering, avoid applying any stress to the LED package while heated. 5 NICHIA STS-DA1-1555A <Cat.No.110318> TAPE AND REEL DIMENSIONS 3.5 ±0.05 Cathode Mark 0.25±0.05 Nxxx064x STS-DA7-0165 (単位 Unit: mm) 3.65 ±0.1 2±0.05 1.75 ±0.1 4±0.1 Φ1.5+0.1 -0 管理番号 No. 8 +0.3 -0.1 テーピング部 Tape 2.15±0.1 4±0.1 Φ1+0.25 -0 2.85±0.1 エンボスキャリアテープ Embossed Carrier Tape トレーラ部/リーダ部 Trailer and Leader トップカバーテープ Top Cover Tape 引き出し方向 Feed Direction トレーラ部最小160mm（空部） Trailer 160mm MIN(Empty Pockets) LED装着部 Loaded Pockets 引き出し部最小100mm（空部） Leader with Top Cover Tape 100mm MIN(Empty Pocket) リーダ部最小400mm Leader without Top Cover Tape 400mm MIN リール部 Reel 180+0 -3 11.4±1 9±0.3 * 数量は1リールにつき 2000個入りです。 Quantity per reel=2000pcs Φ * JIS C 0806電子部品テーピングに準拠しています。 The tape packing method complies with JIS C 0806 (Packaging of Electronic Components on Continuous Tapes). ± 21 ±0.2 ラベル Label Φ 13 ± 0. 2 f 13 .8 Φ60 +1 -0 8 0. f2 1 ±0 6 NICHIA STS-DA1-1555A <Cat.No.110318> PACKAGING - TAPE & REEL シリカゲルとともにリールをアルミ防湿袋に入れ、熱シールにより封をします。 The reel is placed in the moisture proof bag with a moisture absorbent material. The bag is heat sealed. 管理番号 No. Nxxxxxxx STS-DA7-0006A ラベル Label シリカゲル Moisture Absorbent Material リール Reel XXXX LED TYPE Nxxxxxxx ******* LOT YMxxxx-RRR QTY. PCS RoHS NICHIA CORPORATION 491 OKA, KAMINAKA, ANAN, TOKUSHIMA, JAPAN 熱シール Seal アルミ防湿袋 Moisture Proof Foil Bag アルミ防湿袋を並べて入れ、ダンボールで仕切ります。 The moisture proof foil bags are packed in a cardboard box with corrugated partition. ラベル Label XXXX LED TYPE Nxxxxxxx ******* RANK RRR PCS QTY. RoHS NICHIA CORPORATION 491 OKA, KAMINAKA, ANAN, TOKUSHIMA, JAPAN Nichia LED * 客先型名を*******で示します。 客先型名が設定されていない場合は空白です。 ******* is the customer part number. If not provided, it is not indicated on the label. * ロット表記方法についてはロット番号の項を 参照して下さい。 For details, see "LOT NUMBERING SCHEME" in this document. * ランク分けがない場合はランク表記はありません。 The label does not have the RANK field for un-ranked products. * 本製品はテーピングしたのち、輸送の衝撃から保護するためダンボールで梱包します。 The products are taped and reeled, and then packed in moisture-proof bags. The moisture-proof bags are packed in cardboard boxes to prevent damage during shipment. * 取り扱いに際して、落下させたり、強い衝撃を与えたりしますと、製品を損傷させる原因になりますので注意して下さい。 Do not drop the cardboard box or expose it to shock. If the box falls, the products could be damaged. * ダンボールには防水加工がされておりませんので、梱包箱が水に濡れないよう注意して下さい。 The cardboard box is not water-resistant. Do not expose to water. * 輸送、運搬に際して弊社よりの梱包状態あるいは同等の梱包を行って下さい。 Customer is advised to pack the products in the original packaging or equivalent in transit. 7 NICHIA STS-DA1-1555A <Cat.No.110318> LOT NUMBERING SCHEME Lot Number is presented by using the following alphanumeric code. YMxxxx - RRR Y - Year Year Y 2009 9 2010 A 2011 B 2012 C 2013 D 2014 E M - Month Month M Month M 1 1 7 7 2 2 8 8 3 3 9 9 4 4 10 A 5 5 11 B 6 6 12 C xxxx-Nichia's Product Number RRR-Ranking by Color Coordinates, Ranking by Luminous Intensity 8 NICHIA STS-DA1-1555A <Cat.No.110318> DERATING CHARACTERISTICS 管理番号 No. カソード側はんだ接合部温度-許容順電流特性 Solder Temperature(Cathode Side) vs Allowable Forward Current Derating2 50 40 40 (76, 30.0) 30 20 10 (110, 10.0) Allowable Forward Current(mA) 50 許容順電流 許容順電流 Allowable Forward Current(mA) 周囲温度-許容順電流特性 Ambient Temperature vs Allowable Forward Current Derating1 NESx064x STS-DA7-0856 (105, 30.0) 30 (110, 25.0) 20 10 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 周囲温度 カソード側はんだ接合部温度 Ambient Temperature(°C) Solder Temperature(Cathode Side)(°C) デューティー比-許容順電流特性 Duty Ratio vs Allowable Forward Current Duty 120 TA =25°C 許容順電流 Allowable Forward Current(mA) 1000 100 30 10 1 10 100 デューティー比 Duty Ratio(%) 株式会社 小糸製作所殿 専用 KOITO MANUFACTURING CO., LTD. Only 9 NICHIA STS-DA1-1555A <Cat.No.110318> OPTICAL CHARACTERISTICS * 本特性は参考です。 All characteristics shown are for reference only and are not guaranteed. 管理番号 No. 発光スペクトル Spectrum NESG064 STS-DA7-0802 T A=25°C IF=20mA Spectrum 1.0 相対発光強度 Relative Emission Intensity(a.u.) 0.8 0.6 0.4 0.2 0.0 400 450 500 550 600 650 700 波長 Wavelength(nm) Directivity1 指向特性 Directivity T A=25°C IFP=20mA -20° -10° 0° 10° 20° 30° -30° 40° -40° 50° 放射角度 Radiation Angle -50° -60° 60° -70° 70° 80° -80° -90° 90° 1 0.5 0 0.5 1 相対光度 Relative Luminosity(a.u.) 株式会社 小糸製作所殿 専用 KOITO MANUFACTURING CO., LTD. Only 10 NICHIA STS-DA1-1555A <Cat.No.110318> FORWARD CURRENT CHARACTERISTICS / TEMPERATURE CHARACTERISTICS * 本特性は参考です。 All characteristics shown are for reference only and are not guaranteed. 順電圧-順電流特性 Forward Voltage vs Forward Current 管理番号 No. 周囲温度-順電圧特性 Ambient Temperature vs Forward Voltage VfIf T A=25°C 100 NESG064 STS-DA7-0803 IFP= 5 mA IFP=20 mA IFP= 60 mA TaVf 4.5 順電圧 Forward Voltage(V) 順電流 Forward Current(mA) 4.0 20 10 3.5 3.0 2.5 1 2.0 2.0 2.5 3.0 3.5 4.0 4.5 -60 -40 -20 順電圧 Forward Voltage(V) 0 20 40 60 80 100 120 周囲温度 Ambient Temperature(°C) 周囲温度-相対光度特性 順電流-相対光度特性 Forward Current vs Relative Luminosity Ambient Temperature vs Relative Luminosity IfIv T A=25°C TaIv IFP= 20 mA 1.4 3.5 相対光度 Relative Luminosity(a.u.) 相対光度 Relative Luminosity(a.u.) 3.0 2.5 2.0 1.5 1.0 1.2 1.0 0.8 0.5 0.6 0.0 0 20 40 60 80 順電流 Forward Current(mA) 100 120 -60 -40 -20 0 20 40 60 80 100 120 周囲温度 Ambient Temperature(°C) 株式会社 小糸製作所殿 専用 KOITO MANUFACTURING CO., LTD. Only 11 NICHIA STS-DA1-1555A <Cat.No.110318> FORWARD CURRENT CHARACTERISTICS / TEMPERATURE CHARACTERISTICS * 本特性は参考です。 All characteristics shown are for reference only and are not guaranteed. 順電流-色度(主波長)特性 Forward Current vs Chromaticity Coordinate(λd) Ifxy 管理番号 No. NESG064 STS-DA7-0804 TA=25°C 0.80 0.75 1mA(532nm) 5mA(530nm) 0.70 y 20mA(525nm) 30mA(523nm) 0.65 100mA(517nm) 0.60 0.55 0.05 0.10 0.15 0.20 0.25 0.30 x IfλD 周囲温度-主波長特性 Ambient Temperature vs Dominant Wavelength T A=25°C IFP= 20mA TaλD 540 535 535 530 525 520 Dominant Wavelength(nm) 540 主波長 主波長 Dominant Wavelength(nm) 順電流-主波長特性 Forward Current vs Dominant Wavelength 530 525 520 515 515 510 510 1 10 順電流 Forward Current(mA) 100 -60 -40 -20 0 20 40 60 80 100 120 周囲温度 Ambient Temperature(°C) 株式会社 小糸製作所殿 専用 KOITO MANUFACTURING CO., LTD. Only 12 NICHIA STS-DA1-1555A <Cat.No.110318> RELIABILITY (1) Tests and Results Reference Test Standard Resistance to Test Test Conditions Duration JEITA ED-4701 Tsld=260°C, 10sec, 2reflows, 300 301 Precondition: 30°C, 70%RH, 168hr Solderability JEITA ED-4701 Tsld=245±5°C, 5sec, (Reflow Soldering) 303 303A Lead-free Solder(Sn-3.0Ag-0.5Cu) Soldering Heat (Reflow Soldering) 0/22 #3 0/22 100cycles #1 0/100 100cycles #1 0/100 10cycles #1 0/100 TA=110°C 1000hours #1 0/100 TA=60°C, RH=90% 1000hours #1 0/100 TA=-40°C 1000hours #1 0/100 TA=25°C, IF=30mA 1000hours #2 0/100 TA=85°C, IF=25mA 1000hours #2 0/100 60°C, RH=90%, IF=20mA 1000hours #2 0/100 TA=-40°C, IF=20mA 1000hours #2 0/100 1time #1 0/22 48minutes #1 0/10 #1 0/10 #1 0/22 Precondition: 30°C, 70%RH, 168hr JEITA ED-4701 -40°C(30min)~25°C(5min)~ 100 105 110°C(30min)~25°C(5min) Moisture Resistance JEITA ED-4701 25°C~65°C~-10°C, 90%RH, (Cyclic) 200 203 24hr per cycle High Temperature JEITA ED-4701 Storage 200 201 Temperature Humidity JEITA ED-4701 Storage 100 103 Low Temperature JEITA ED-4701 Storage 200 202 Room Temperature Operating Life High Temperature Operating Life Temperature Humidity Operating Life Low Temperature Operating Life Permanence of Marking Vibration JEITA ED-4701 Isopropyl Alcohol, 23±5°C, 500 501 Dipping Time: 5min JEITA ED-4701 200m/s2, 100~2000~100Hz, 400 403 4cycles, 4min, each X, Y, Z JEITA ED-4701 HBM, 2kV, 1.5kΩ, 100pF, 3pulses, 300 304 alternately positive or negative Free Fall 3drops from a height of 75cm Electrostatic Discharges Failed/Tested #1 10sec transfer, 300 307 Temperature Cycle # Units -40°C to 110°C, 1min dwell, JEITA ED-4701 Thermal Shock Failure Criteria NOTES: Measurements are performed after allowing the LEDs to return to room temperature. (2) Failure Criteria Criteria # #1 #2 #3 Items Conditions Failure Criteria Forward Voltage(VF) IF=20mA >U.S.L.×1.1 Luminous Intensity(IV) IF=20mA <L.S.L.×0.7 Forward Voltage(VF) IF=20mA >U.S.L.×1.1 Luminous Intensity(IV) IF=20mA <L.S.L.×0.5 Solderability - Less than 95% solder coverage U.S.L. : Upper Specification Limit L.S.L. : Lower Specification Limit (3) Reference The projected average time to 70% lumen maintenance for this product is 50000 hours under the conditions of Nichia reliability test: TA=25°C, IF=25mA, and 10000 hours under the conditions of Nichia reliability test: TA=85°C, IF=25mA, Nichia standard circuit board. （Test board: FR4 board thickness=1.6mm, copper layer thickness=35µm） 13 NICHIA STS-DA1-1555A <Cat.No.110318> CAUTIONS (1) Storage Conditions Storage Temperature Humidity Time Before Opening Aluminum Bag ≤30°C ≤90%RH Within 1 Year from Delivery Date After Opening Aluminum Bag ≤30°C ≤70%RH ≤168hours 65±5°C - ≥24hours Baking ● This product is compliant to JEDEC MSL 3 or equivalent. See IPC/JEDEC STD-020 for the details of the moisture sensitivity levels. ● Interface delamination can occur due to vaporization and expansion of absorbed moisture in the LED packages caused by soldering heat, which may result in degradation in optical performance. To minimize moisture absorption into the products during the transportation and storage, the products are packed in a moisture-proof aluminum bag. Desiccants (silica gel) inside the packing turn from blue to red as it absorbs moisture. ● After opening the moisture-proof aluminum bag, the products should be completed soldering process within the range of the conditions above. If unused LEDs remain, they should be stored with desiccants (silica gel) in hermetically sealed container. Nichia recommends using the original moisture-proof bag for storage. ● After the "Period After Opening" specified above, or if the desiccants (silica gel) are no longer blue, the products need to be baked. Note that baking must only be done once. ● Customer is advised to keep the LEDs in an airtight container when not in use as exposure to a corrosive environment might cause the plated metal parts of the product to tarnish, which might lead to difficulties in soldering and/or adverse effects on optical characteristics. It is also recommended to return the LEDs to the original moisture proof bag and seal the moisture proof bag again. ● After assembly and during use, silver plating can be affected by the corrosive gases emitted by components and materials in close proximity of the LEDs within an end product, and the gases entering into the product from the external atmosphere. The above should be taken into consideration when designing. After assembly and during use, silver plating can be affected by the corrosive gases emitted by components and materials in close proximity of the LEDs within an end product, and the gases entering into the product from the external atmosphere. The above should be taken into consideration when designing. Resin materials, in particular, may contain substances which affects on silver plating, such as halogen. ● To avoid condensation, the products must not be stored in the areas where temperature and humidity fluctuate greatly. (2) Directions for Use ● In designing a circuit, the current through each LED must not exceed the Absolute Maximum Rating specified for each LED. It is recommended to use Circuit B which regulates the current flowing through each LED. In the meanwhile, when driving LEDs with a constant voltage in Circuit A, the current through the LEDs may vary due to the variation in Forward Voltage characteristics of the LEDs. (A) (B) ... ... ● This product should be operated in forward bias. A driving circuit must be designed so that the product is not subjected to either forward or reverse voltage while it is off. In particular, if a reverse voltage is continuously applied to the product, such operation can cause migration resulting in LED damage. ● For stabilizing the LED characteristics, it is recommended to operate at 10% of the rated current or higher. ● For outdoor use, necessary measures should be taken to prevent water, moisture and salt air damage. 14 NICHIA STS-DA1-1555A <Cat.No.110318> (3) Handling Precautions ● When handling the product, do not touch it directly with bare hands as it may contaminate the surface and affect on optical characteristics. In the worst cases, excessive force to the product might result in catastrophic failure due to package damage and/or wire breakage. ● When handling the product with tweezers, make sure that excessive force is not applied to the resin portion of the product. Failure to comply can cause the resin portion of the product to be cut, chipped, delaminated and/or deformed, and wire to be broken, and thus resulting in catastrophic failure. ● If the product is dropped, it might be damaged. ● Do not stack assembled PCBs together. Failure to comply can cause the resin portion of the product to be cut, chipped, delaminated and/or deformed, and wire to be broken, and thus resulting in catastrophic failure. (4) Design Consideration ● PCB warpage after mounting the products onto a PCB can cause the package to break. The LEDs should be placed so as to minimize the stress on the LEDs due to PCB bow and twist. ● The position and orientation of the LEDs affect how much mechanical stress is exerted on the LEDs placed near the score lines. The LEDs should be placed so as to minimize the stress on the LEDs due to board flexing. ● Board separation must be performed using special jigs, not with hands. (5) Electrostatic Discharge (ESD) ● The products are sensitive to static electricity or surge voltage. An ESD event may damage its die or reduce its reliability performance. When handling the products, measures against electro static discharge, including the followings, are strongly recommended. Eliminating the charge; Wrist strap, ESD footwear and garments, ESD floors Grounding the equipment and tools at workstation ESD table/shelf mat (conductive materials) ● Proper grounding techniques are required for all devices, equipment and machinery used in the assembly of the products. Also note that surge protection should be considered in the design of customer products. ● If tools or equipment contain insulating materials, such as glass or plastic, proper measures against electro static discharge, including the followings, are strongly recommended. Dissipating the charge with conductive materials Preventing the charge generation with moisture Neutralizing the charge with ionizers ● When performing the characteristics inspection of the LEDs in your application, customer is advised to check on the LEDs whether or not they are damaged by ESD. Such damage can be detected during forward voltage measurement or light up test at low current. (the recommended current is 1mA or lower) ● ESD-damaged LEDs may have a current flow at low voltage, or no longer light up at low current. Failure Criteria: VF<2.0V at IF=0.5mA (6) Thermal Management ● Thermal management is an important factor when designing your product by using the LEDs. The rise in LED die temperature can be affected by PCB thermal resistance or/and LED spacing as mounted on the board. Customer is advised to design the product to ensure that the LED die temperature does not exceed the required maximum Junction Temperature (TJ). ● Drive current should be determined for the surrounding ambient temperature (TA) to dissipate the heat from the product. (7) Cleaning ● If required, isopropyl alcohol (IPA) should be used. Other solvents may cause premature failure to the LEDs due to the damage to the resin portion. The effects of such solvents should be verified prior to use. In addition, the use of CFCs such as Freon is heavily regulated. ● Ultrasonic cleaning is not recommended for the LEDs since it may adversely effect on the LEDs by the ultrasonic power and LED assembled condition. If it is unavoidable, customer is advised to check prior to use that the cleaning will not damage the LEDs. 15 NICHIA STS-DA1-1555A <Cat.No.110318> (8) Eye Safety ● The International Electrical Commission (IEC) published in 2006, IEC 62471:2006 Photobiological safety of lamps and lamp systems which includes LEDs within its scope. Meanwhile LEDs were removed from the scope of the IEC 60825-1:2007 laser safety standard, the 2001 edition of which included LED sources within its scope. However, keep it mind that some countries and regions have adopted standards based on the IEC laser safety standard IEC 60825-1:2001 which includes LEDs within its scope. Following IEC 62471:2006, most of Nichia LEDs can be classified as belonging to either Exempt Group or Risk Group 1. Especially a high-power LED, that emits light containing blue wavelengths, may be in Risk Group 2. Great care should be taken when viewing directly the LED driven at high current or the LED with optical instruments, which greatly increase the hazard to your eyes. ● Viewing a flashing light may cause eye discomfort. When incorporating the LED into your product, precaution should be taken to avoid adverse effect on human body caused by the light stimulus. (9) Others ● The LEDs described in this brochure are intended to be used for ordinary electronic equipment (such as office equipment, communications equipment, measurement instruments and household appliances). Consult Nichia's sales staff in advance for information on the applications in which exceptional quality and reliability are required, particularly when the failure or malfunction of the LEDs may directly jeopardize life or health (such as for airplanes, aerospace, submersible repeaters, nuclear reactor control system, automobiles, traffic control equipment, life support systems and safety devices). ● The customer shall not reverse engineer by disassembling or analysis of the LEDs without having prior written consent from Nichia. When defective LEDs are found, the customer shall inform Nichia directly before disassembling or analysis. ● Customer and Nichia shall agree the official specification of supplied products prior to the start of a customer’s volume production. ● The appearance and specifications of the product may be modified for improvement without notice. 16