The documentation process conversion measures necessary to comply with this revision shall be completed by 10 December 1999. INCH-POUND MIL-PRF-19500/581A 10 September 1999 SUPERSEDING MIL-S-19500/581 23 April 1990 PERFORMANCE SPECIFICATION SHEET SEMICONDUCTOR DEVICE, TRANSISTOR, NPN, SILICON AMPLIFIER, TYPES 2N4237, 2N4238 AND 2N4239 JAN, JANTX AND JANTXV This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification covers the performance requirements for NPN , silicon, amplifier transistors. Three levels of product assurance are provided for each device type as specified in MIL-PRF-19500. 1.2 Physical dimensions. See figure 1, (TO-39). 1.3 Maximum ratings. Unless otherwise specified, TA = +25°C. Type PT 1/ PT VCBO VCEO VEBO IC IB Top and TSTG TA = +25°C TC = +25°C 1/ 2/ 2N4237 2N4238 2N4239 W W V dc V dc V dc A dc A dc °C 1.0 1.0 1.0 6.0 6.0 6.0 50 80 100 40 60 80 6.0 6.0 6.0 1.0 1.0 1.0 0.5 0.5 0.5 -65 to +200 -65 to +200 -65 to +200 1/ Derate linearly 5.7 mW/°C for TA > +25°C; 1/ Derate linearly 34 mW/°C for TC > +25°C; 1.4 Primary electrical characteristics at TA = +25°C. hFE at VCE = 1.0 V dc 1/ Limits RθJC hFE1 hFE2 hFE3 IC = 100 mA dc IC = 250 mA dc IC = 500 mA dc max /hfe / f = 10 MHz Cobo f = 1.0 MHz VCE = 10 V dc VCB = 10 V dc IC = 100 mA dc IC = 0 °C Min Max 30 30 150 30 29 VCE(sat)2 1/ IC = 1.0 A dc IB = 0.1 A dc pF VBE(sat)2 1/ IC = 1.0 A dc IB = 0.1 A dc V dc 3.0 100 0.6 1.5 1 Pulsed see 4.5.1. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Defense Supply Center Columbus, ATTN: DSCC-VAC, 3990 East Broad Street, Columbus, OH 43216-5000, by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. AMSC N/A DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. FSC 5961 MIL-PRF-19500/581A 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cited in sections 3 and 4 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement thereto, cited in the solicitation (see 6.2). SPECIFICATION DEPARTMENT OF DEFENSE MIL-PRF-19500 - Semiconductor Devices, General Specification for. STANDARD MILITARY MIL-STD-750 - Test Methods for Semiconductor Devices. (Unless otherwise indicated, copies of the above specifications, standards, and handbooks are available from the Defense Automated Printing Service, Building 4D (DPM-DODSSP), 700 Robbins Avenue, Philadelphia, PA 19111-5094.) 2.3 Order of precedence. In the event of a conflict between the text of this document and the references cited herein (except for related associated specifications or specification sheets), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Associated specification. The individual item requirements shall be in accordance with MIL-PRF-19500, and as specified herein. 3.2 Abbreviations, symbols, and definitions. Abbreviations, symbols, and definitions used herein shall be as specified in MIL-PRF19500. 3.3 Interface requirements and physical dimensions. The interface requirements and physical dimensions shall be as specified in MIL-PRF-19500 and on figure 1 (TO-39) herein. 3.3.1 Lead finish. Lead finish shall be solderable as defined in MIL-PRF-19500, MIL-STD-750, and herein. Where a choice of lead material or finish is desired, it shall be specified in the acquisition document (see 6.2). 3.4 Marking. Marking shall be in accordance with MIL-PRF-19500. 3.5 Electrical performance characteristics. Unless otherwise specified herein, the electrical performance characteristics are as specified in 1.3, 1.4, and table I herein. 3.6 Electrical test requirements. The electrical test requirements shall be the subgroups specified in table I herein. 3.7 Qualification. Devices furnished under this specification shall be products that are authorized by the qualifying activity for listing on the applicable qualified products list before contract award (see 4.2 and 6.3). 2 MIL-PRF-19500/581A FIGURE 1. Physical dimensions for (TO-39). 3 MIL-PRF-19500/581A Symbol (see note 3) Dimensions Inches Notes Millimeters Min Max Min Max CD 0.305 0.355 7.75 8.51 CH 0.240 0.260 6.10 6.60 HD 0.335 0.370 8.51 9.39 LC 0.200 BSC 5.08 BSC 10 LD 0.016 0.021 0.41 0.53 10, 11 LL 0.500 0.750 12.70 19.05 11, 12 LU 0.016 0.019 0.41 0.48 11, 12 L1 --- 0.050 --- 1.27 11, 12 L2 0.250 --- 6.35 --- 11, 12 P 0.100 --- 2.54 --- 9 Q --- 0.050 --- 1.27 8 0.25 13 R 0.010 TL 0.029 0.045 0.74 1.14 7 TW 0.028 0.034 0.72 0.86 6 α 45° BSC Term 1 Emitter Term 2 Base Term 3 Collector 10 FIGURE 1. Physical dimensions for (TO-39) continued. 4 MIL-PRF-19500/581A NOTES: 1. Dimensions are in inches. 2. Metric equivalents are given in parentheses for general information only. 3. Refer to applicable symbol list. 4. The US Government preferred system of measurement is the metric SI system. However, this item was originally designed using inch-pound units of measurement. In the event of a conflict between the metric and inch-pound units, the inch-pound units shall take precedence. 5. Lead number 1 is the emitter, lead number 2 is the base, lead number 4 is omitted from this outline. The collector is number 3 and is electrically connected to the case. 6. Beyond r (radius) max, TW shall be held for a minimum length of 0.011 inch (0.28 mm). 7. TL measured from maximum HD. 8. Outline in this zone is not controlled. 9. CD shall not vary more than 0.010 inch (0.25 mm) in zone P. This zone is controlled for automatic handling. 10. Leads at gauge plane 0.054 + 0.001 - 0.000 inch (1.37 +0.03 - 0.00 mm) below seating plane shall be within 0.007 inch (0.18 mm) radius of true position (TP) at maximum material condition (MMC) relative to tab at MMC. 11. LU applies between L1 and L2. LD applies between L2 and LL minimum. Diameter is uncontrolled in L1 and beyond LL minimum. 12. All three leads. 13. r (radius) applies to both inside corners of tab. FIGURE 1. Physical dimensions for (TO-39) continued. 5 MIL-PRF-19500/581A 4. VERIFICATION 4.1 Classification of inspections. The inspection requirements specified herein are classified as follows: a. Qualification inspection (see 4.2). b. Screening (see 4.3) c. Conformance inspection (see 4.4). 4.2 Qualification inspection. Qualification inspection shall be in accordance with MIL-PRF-19500 and herein. 4.2.1 Group E inspection. Group E inspection shall be conducted in accordance with MIL-PRF-19500 and herein. 4.3 Screening (JANTX, and JANTXV levels only). Screening shall be in accordance with table IV of MIL-PRF-19500, and as specified herein. The following measurements shall be made in accordance with table I herein. Devices that exceed the limits of table I herein shall not be acceptable. Screen (see table IV of MIL-PRF-19500) Measurement JANTX and JANTXV level 1/ Method 3131 (see 4.5.2) 11 ICBO, and hFE2 12 See 4.3.1 13 Subgroup 2 of table I herein ∆ICBO = 100 percent of initial value, or 10 nA dc whichever is greater; ∆hFE2 = ± 15 percent of initial value. 1/ Shall be performed anytime before screen 10. 4.3.1 Power burn-in conditions. Power burn-in conditions are as follows: VCB ≥ 20 V dc; PT = 1.0 W at TA = 30 °C ± 5°C. NOTE: No heat sink or forced air cooling on the devices shall be permitted. 4.4 Conformance inspection. Conformance inspection shall be in accordance with MIL-PRF-19500, and as specified herein 4.4.1 Group A inspection. Group A inspection shall be conducted in accordance with table V of MIL-PRF-19500, and table I herein. End-point electrical measurements shall be in accordance with table I, subgroup 2. 6 MIL-PRF-19500/581A 4.4.2 Group B inspection. Group B inspection shall be conducted in accordance with the conditions specified. Separate samples may be used for each step. In the event of a group B failure, the manufacturer may pull a new sample at double the sample size from either the failed assembly lot or from another assembly lot from the same wafer lot. If the new “assembly lot” option is exercised, the failed assembly lot shall be scrapped. Electrical measurements (end-points) shall be in accordance with table I, subgroup 2 herein. Delta measurements shall be in accordance with table II herein. Step Method Condition 1 1039 Steady-state life: Test condition B, 340 hours, VCB ≥ 10 V dc, TJ = 175°C min. No heat sink or forced-air cooling on the devices shall be permitted. n = 45 devices, c=0 2 1039 The steady state life test of step 1 shall be extended to 1,000 hours for each die design. Samples shall be selected from a wafer lot every twelve months of wafer production, however, Group B shall not be required more than once for any single wafer lot. n = 45, c = 0. 3 1032 High-temperature life (non-operating), TA = +200°C. n = 22, c = 0 4.4.2.1 Group B sample selection. Samples selected from group B inspection shall meet all of the following requirements: a. For JAN, JANTX, and JANTXV samples shall be selected randomly from a minimum of three wafers (or from each wafer in the lot) from each wafer lot. See MIL-PRF-19500. b. Must be chosen from an inspection lot that has been submitted to and passed group A, subgroup 2, conformance inspection. When the final lead finish is solder or any plating prone to oxidation at high temperature, the samples for life test (group B for JAN, JANTX, and JANTXV) may be pulled prior to the application of final lead finish. 4.4.3 Group C inspection. Group C inspection shall be conducted in accordance with the conditions specified for subgroup testing in table VII of MIL-PRF-19500. Electrical measurements (end-points) shall be in accordance with table I, subgroup 2 herein. Delta measurements shall be in accordance with table II herein. 4.4.3.1 Group C inspection, table VII (JAN, JANTX, and JANTXV) of MIL-PRF-19500. Subgroup Method Condition C2 2036 Test condition E. C6 1026 VCB ≥ 10 V dc; adjust PT to achieve TJ = + 175 °C minimum; TA = + 30 °C ± 5°C. No heat sink or forced-air cooling on the device shall be permitted. 4.4.3.2 Group C sample selection. Samples for subgroups in group C shall be chosen at random from any lot containing the intended package type and lead finish procured to the same specification which is submitted to and passes group A tests for conformance inspection. Testing of a subgroup using a single device type enclosed in the intended package type shall be considered as complying with the requirements for that subgroup. 4.4.4 Group E inspection. Group E inspection shall be conducted in accordance with the conditions specified for subgroup testing in table IX of MIL-PRF-19500 and as follows. Electrical measurements (end-points) shall be in accordance with table I, subgroup 2 herein. Delta measurements shall be in accordance with table II herein. 4.4.4.1 Group E inspection, table IX of MIL-PRF-19500. Subgroup Method Condition Sampling plan E2 1039 Test condition A, 1,000 hours. 22 devices, c = 0 E4 3161 RθJC = 29 °C/W maximum. See 4.5.3 22 devices, c = 0 4.5 Methods of inspection. Methods of inspection shall be as specified in the appropriate tables and as follows. 7 MIL-PRF-19500/581A 4.5.1 Pulse measurements. Conditions for pulse measurement shall be as specified in section 4 of MIL-STD-750. 4.5.2 Thermal response( ∆VBE measurement). The ∆VBE measurement shall be performed in accordance with method 3131 of MILSTD-750. The ∆VBE conditions and maximum VBE limit shall be derived by each vendor. The chosen ∆VBE measurement and conditions for each device in the qualification lot and read and record measurements shall be submitted in the qualification report and a thermal response curve shall be plotted. The chosen VBE values shall be considered final after the manufacturer has had the opportunity to test five consecutive lots. The following measurements shall apply: a. Measuring current (IM) ........................................................ 5 mA. b. Measurement voltage (VCE ) ................................................. 20 V (same as VH). c. Collector heating current (IH) ............................................... 300 mA (minimum for). d. Collector-emitter heating voltage ........................................... 20 V (minimum). e. Heating time (tH)................................................................... 1200 ms. f. Measurement time delay (tMD) ............................................ 5 µs. f. Sample window time (tSW ) .................................................. 10 µs maximum. 4.5.3 Thermal resistance. Thermal resistance measurements shall be conducted in accordance with method 3131 of MIL-STD-750. Maximum limit of RθJC shall be 29°C/W. The following test conditions shall apply: a. Heating power shall be chosen such that the calculated junction to reference point temperature difference is greater than + 50°C. b. Collector to emitter voltage magnitude shall be 20 V dc. c. Reference temperature measuring point shall be the case. d. Reference point temperature shall be + 25°C ≤ TR ≤ +35°C and recorded before the test is started. e. Mounting arrangement shall be with heat sink to case. f. Maximum limit shall be RθJC = 29°C/W. 8 MIL-PRF-19500/581A TABLE I. Group A inspection. Inspection 1/ MIL-STD-750 Method Symbol Conditions Limits Min Unit Max Subgroup 1 2/ Visual and mechanical 3/ examination 2071 n = 45 devices, c = 0 Solderability 3/ 2026 n = 15 leads, c = 0 Resistance to 3/ 4/ solvent 1022 n = 15 devices, c = 0 Temp cycling 3/ 1051 Test condition C, 25 cycles. n = 22 devices, c = 0 Heremetic seal 1071 n = 22 devices, c = 0 Fine leak Gross leak Electrical measurements Bond strength 3/ Group A, subgroup 2 2037 Precondition TA = +250°C at t = 24 hrs or TA = +300°C at t = 2 hrs, n = 11 wires, c = 0 Subgroup 2 Breakdown voltage collector to emitter 2N4237 2N4238 2N4239 3011 Collector emitter cutoff current 2N4237 2N4238 2N4239 3041 Collector to baser cutoff current 2N4237 2N4238 2N4239 3036 Emitter to base cutoff current 3061 Forward current transfer ratio 3076 Bias condition D, pulsed (see 4.5.1) IC = 100 mA dc Vdc V(BR)CEO 50 80 100 Bias condition A, VBE = 1.5 V dc ICEX1 100 nA dc ICBO 100 nA dc Bias condition D, VBE = 6 V dc IEBO 0.5 mA dc Pulsed (see 4.5.1), IC = 100 mA dc VCE = 1.0 V dc hFE1 VCE = 50 V dc VCE = 80 V dc VCE = 100 V dc Bias condition D VCE = 50 V dc VCE = 80 V dc VCE = 100 V dc See footnotes at end of table. 9 30 MIL-PRF-19500/581A TABLE I. Group A inspection - Continued. Inspection 1/ MIL-STD-750 Method Symbol Conditions Limits Unit Min Max 150 Subgroup 2 Continued Forward current transfer ratio 3076 Pulsed (see 4.5.1), IC = 250 mA dc VCE = 1.0 V dc hFE2 30 Forward current transfer ratio 3076 Pulsed (see 4.5.1), IC = 500 mA dc VCE = 1.0 V dc hFE3 30 Collector to emitter voltage (saturated 3071 Pulsed (see 4.5.1), IC = 500 mA dc IB = 50 mA dc VCE(sat)1 0.3 V dc Collector to emitter voltage (saturated 3071 Pulsed (see 4.5.1), IC = 1.0 A dc IB = 0.1 A dc VCE(sat)2 0.6 V dc Base emitter voltage 3066 Test condition A, pulsed (see 4.5.1), IC = 500 mA dc , IB = 50 mA dc VBE(sat)1 1.0 V dc Base emitter voltage 3066 Test condition A, pulsed (see 4.5.1), IC = 1.0 mA dc , IB = 0.1 A dc VBE(sat)2 1.5 V dc ICEX2 1.0 mA dc 100 pF Subgroup 3 High-temperature operation: Collector to emitter cutoff current 2N4237 2N4238 2N4239 TA = +150°C 3041 VCE = 30 V dc VCE = 50 V dc VCE = 70 V dc Low-temperature operation: Forward current transfer ratio Bias condition A, VBE = 1.5 V dc TA = -55°C 3076 Pulsed (see 4.5.1), IC = 250 mA dc VCE = 1.0 V dc hFE4 15 Magnitude of small-signal short-circuit forward-current transfer ratio 3306 IC = 100 mA dc, VCE = 10 V dc, f = 10 MHz |hFE | 3 Open circuit output capacitance 3236 IE = 0, VCB = 10 V dc, f = 100 kHz Cobo Subgroup 4 See footnotes at end of table. 10 MIL-PRF-19500/581A TABLE I. Group A inspection - Continued. Inspection 1/ MIL-STD-750 Method Symbol Conditions Limits Min Subgroup 5 Safe operating area (continuous dc) 5/ 3051 TC = +25°C; t ≥ 0.5 s, 1 cycle. Test 1 IC = 1.0 A dc, VCE = 6 V dc, Test 2 IC = 500 mA dc, VCE = 12 V dc, Test 3 2N4237 IC = 166 mA dc, VCE = 30 V dc, 2N4238 IC = 100 mA dc, VCE = 50 V dc, 2N4239 End point electrical measurements IC = 71 mA dc, VCE = 70 V dc, See table I, subgroup 2 herein. Subgroups 6 and 7 Not applicable 1/ For sampling plan, see MIL-PRF-19500. 2/ For resubmission of failed subgroup A1, double the sample size of the failed test or sequence of tests. 3/ Separate samples may be used. 4/. Not required for laser marked devices. 5/ L = 5 mH (2 each Essex Stancor C-2688 in parallel 1A, 0.5 ohm, or equivalent (see 4.5.2). 11 Unit Max MIL-PRF-19500/581A TABLE II. Groups B, C, and E delta measurements. 2/ 3/ 4/ Step Inspection MIL-STD-750 Method 1. Collector to base cutoff current 3036 2N4237 2N4238 2N4239 2. Forward current transfer ratio Symbol Conditions Bias condition D Min ∆hFE2 1/ ± 25 percent change from initial recorded value. VCB = 50 V dc VCB = 80 V dc VCB = 100 V dc 3076 IC = 250 mA dc VCE = 1.0 V dc; Pulsed (see 4.5.1) Subgroup 3, see table II herein, steps 1 and 2. Subgroup 6, see table II herein, steps 1 and 2. 3/ The delta measurements for table VII of MIL-PRF-19500 are as follows: Subgroup 6, see table II herein, steps 1 and 2. 4/ The delta measurements for table IX of MIL-PRF-19500 are as follows: b. Max 100 percent of initial value or 10 nA dc whichever is greater. 2/ The delta measurements for table VIb (JANTX and JANTXV) of MIL-PRF-19500 are as follows: a. Unit ∆ICBO 1/ 1/ Devices which exceed the group A limits for this test shall not be shipped. a. b. Limits Subgroup 1, see table II herein, steps 1 and 2. 12 MIL-PRF-19500/581A 5. PACKAGING 5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or order (see 6.2). When actual packaging of material is to be performed by DoD personnel, these personnel need to contact the responsible packaging activity to ascertain requisite packaging requirements. Packaging requirements are maintained by the Inventory Control Points' packaging activity within the Military Department or Defense Agency, or within the Military Departments' System Command. Packaging data retrieval is available from the managing Military Departments' or Defense Agency's automated packaging files, CD-ROM products, or by contacting the responsible packaging activity. 6. NOTES (This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.) 6.1 Notes. The notes specified in MIL-PRF-19500 are applicable to this specification. 6.2 Acquisition requirements. Acquisition documents must specify the following: a. Issue of DODISS to be cited in the solicitation (see 2.2.1). b. The lead finish as specified (see 3.3.1). c. Type designation and quality assurance level. d. Packaging requirements (see 5.1). 6.3 Qualification. With respect to products requiring qualification, awards will be made only for products which are, at the time of award of contract, qualified for inclusion in Qualified Manufacture’s List QML No.19500 whether or not such products have actually been so listed by that date. The attention of the contractors is called to these requirements, and manufacturers are urged to arrange to have the products that they propose to offer to the Federal Government tested for qualification in order that they may be eligible to be awarded contracts or purchase orders for the products covered by this specification. Information pertaining to qualification of products may be obtained from Defense Supply Center Columbus, ATTN: DSCC-VQE, 3990 East Broad Street, Columbus, OH 43216-5000. 6.4 Application guidance. NPN 2N4237 2N4238 2N4239 The following NPN type transistor is complementary to the PNP device listed herein. PNP 2N4234 2N4235 2N4236 13 MIL-PRF-19500/581A 6.5 Substitution information. Devices covered by this specification are substitutable for the manufacturer's and user's Part or Identifying Number (PIN). This information in no way implies that manufacturer's PIN's are suitable for the military PIN. Military PIN Manufacturer’s CAGE Code Manufacturer’s and user’s PIN JAN2N4237 or JANTX2N4237 or JANTXV2N4237 04713 2N4237 ST1027H JAN2N4238 or JANTX2N4238 or JANTXV2N4238 04713 2N4238 ST1375H JAN2N4238 or JANTX2N4238 or JANTXV2N4238 04713 2N4239 ST690H2 ST693H1 ST693H2 ST693H3 ST693H4 ST693H32 ST7008H1 ST7008H2 ST7008H3 ST7008H4 ST7008H21 ST7008H32 6.6 Changes from previous issue. Marginal notations are not used in this revision to identify changes with respect to the previous issue due to the extensiveness of the changes. Custodians: Army - CR Navy - EC Air Force - 11 DLA - CC Preparing activity: DLA - CC (Project 5961-2032) Review activities: Army - AR, MI, SM Air Force - 13, 19 Navy - AS, CG, MC, OS 14 STANDARDIZATION DOCUMENT IMPROVEMENT PROPOSAL INSTRUCTIONS 1. The preparing activity must complete blocks 1, 2, 3, and 8. In block 1, both the document number and revision letter should be given. 2. The submitter of this form must complete blocks 4, 5, 6, and 7. 3. The preparing activity must provide a reply within 30 days from receipt of the form. NOTE: This form may not be used to request copies of documents, nor to request waivers, or clarification of requirements on current contracts. Comments submitted on this form do not constitute or imply authorization to waive any portion of the referenced document(s) or to amend contractual requirements. I RECOMMEND A CHANGE: 1. DOCUMENT NUMBER MIL-PRF-19500/581A 2. DOCUMENT DATE 990910 3. DOCUMENT TITLE SEMICONDUCTOR DEVICE, TRANSISTOR, NPN, SILICON AMPLIFIER, TYPES 2N4237, 2N4338 AND 2N4239 JAN, JANTX AND JANTXV 4. NATURE OF CHANGE (Identify paragraph number and include proposed rewrite, if possible. Attach extra sheets as needed.) 5. REASON FOR RECOMMENDATION 6. SUBMITTER a. NAME (Last, First, Middle initial) b. ORGANIZATION c. ADDRESS (Include Zip Code) d. TELEPHONE (Include Area Code) COMMERCIAL DSN FAX EMAIL 7. DATE SUBMITTED 8. PREPARING ACTIVITY a. Point of Contact Alan Barone b. TELEPHONE Commercial DSN 614-692-0510 850-0510 c. ADDRESS Defense Supply Center Columbus, ATTN: DSCC-VAC, 3990 East Broad Street, Columbus, OH 43216-5000 IF YOU DO NOT RECEIVE A REPLY WITHIN 45 DAYS, CONTACT: Defense Standardization Program Office (DLSC-LM) 8725 John J. Kingman, Suite 2533, Fort Belvoir, VA 22060-6221 Telephone (703) 767-6888 DSN 427-6888 DD Form 1426, Feb 1999 (EG) Previous editions are obsolete FAX 614-692-6939 EMAIL [email protected] WHS/DIOR, Feb 99