1、BRITISH STANDARD BS EN 60749-4:2002 Semiconductor devices Mechanical and climatic test methods Part 4: Damp heat, steady state, highly accelerated stress test (HAST) The European Standard EN 60749-4:2002 has the status of a British Standard ICS 31.080.01 BS EN 60749-4:2002 This British Standard, hav
2、ing been prepared under the direction of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 10 September 2002 BSI 10 September 2002 ISBN 0 580 40335 1 National foreword This British Standard is the official E
3、nglish language version of EN 60749-4:2002. It is identical with IEC 60749-4:2002. It partially supersedes BS EN 60749:1999. The UK participation in its preparation was entrusted to Technical Committee EPL/47, Semiconductors, which has the responsibility to: A list of organizations represented on th
4、is committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by usin
5、g the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity
6、from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in t
7、he UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 8, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Da
8、te CommentsEUROPEAN STANDARD EN 60749-4 NORME EUROPENNE EUROPISCHE NORM August 2002 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Bruss
9、els 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60749-4:2002 E ICS 31.080.01 Partly supersedes EN 60749:1999 + A1:2000 + A2:2001 English version Semiconductor devices Mechanical and climatic test methods Part 4: Damp heat
10、, steady state, highly accelerated stress test (HAST) (IEC 60749-4:2002) Dispositifs semiconducteurs Mthodes dessais mcaniques et climatiques Partie 4: Essai continu fortement accelr de contrainte de chaleur humide (HAST) (CEI 60749-4:2002) Halbleiterbauelemente - Mechanische und klimatische Prfverf
11、ahren Teil 4: Feuchte Wrme, konstant, Prfung mit hochbeschleunigter Wirkung (HAST) (IEC 60749-4:2002) This European Standard was approved by CENELEC on 2002-07-02. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European St
12、andard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, F
13、rench, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgiu
14、m, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.EN 64709-:40022 - 2 Foreword The text of document 47/1602/FDIS, future edition 1 of IEC 60749-4, p
15、repared by IEC TC 47, Semiconductor devices, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60749-4 on 2002-07-02. This mechanical and climatic test method, as it relates to damp heat, steady state, highly accelerated stress test (HAS), is a complete rewrite of the
16、test contained in clause 4C, chapter 3 of EN 60749:1999. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2003-04-01 latest date by which the national standards conflicting wit
17、h the EN have to be withdrawn (dow) 2005-07-01 _ Endorsement notice The text of the International Standard IEC 60749-4:2002 was approved by CENELEC as a European Standard without any modification. _ Page2 EN607494:2002067-944 EI:C0022 3 SEMICONDUCTOR DEVICES MECHANICAL AND CLIMATIC TEST METHODS Part
18、 4: Damp heat, steady state, highly accelerated stress test (HAST) 1 Scope This part of IEC 60749 provides a highly accelerated temperature and humidity stress test (HAST) for the purpose of evaluating the reliability of non-hermetic packaged semiconductor devices in humid environments. 2 HAST test
19、General remarks The HAST test employs severe conditions of temperature, humidity and bias which accelerate the penetration of moisture through the external protective material (encapsulant or seal) or along the interface between the external protective material and the metallic conductors which pass
20、 through it. The stress usually activates the same failure mechanisms as the “85/85” damp heat, steady state humidity test (see IEC 60749-5). As such the test method may be selected from 85 C/85 % RH steady-state life or from this test method. When both test methods are performed, test results of 85
21、 C/85 % RH steady-state life test take priority over HAST. This test method shall be considered destructive. 3 Test apparatus The test requires a pressure chamber capable of maintaining a specified temperature and relative humidity continuously, while providing electrical connections to the devices
22、under test in a specified biasing configuration. 3.1 Controlled conditions The chamber shall be capable of providing controlled conditions of pressure, temperature and relative humidity during ramp-up to and ramp-down from the specified test conditions. 3.2 Temperature profile A permanent record of
23、the temperature profile for each test cycle is recommended so that the validity of the stress can be verified. 3.3 Devices under stress Devices under stress shall be mounted in such a way that temperature gradients are minimized. Devices under stress shall be no closer than 3 cm from internal chambe
24、r surfaces, and shall not be subjected to direct radiant heat from heaters. Boards on which devices are mounted should be oriented to minimize interference with vapour circulation. Page3 EN607494:2002067-944 EI:C0022 4 3.4 Minimize release of contamination Care shall be exercised in the choice of bo
25、ard and socket materials, to minimize release of contamination and to minimize degradation due to corrosion and other mechanisms. 3.5 Ionic contamination Ionic contamination of the test apparatus (card cage, test boards, sockets, wiring storage containers, etc.) shall be controlled to avoid test art
26、ifacts. 3.6 De-ionized water De-ionized water with a minimum resistivity of 1 10 4 m at room temperature shall be used. 4 Test conditions Test conditions consist of a temperature, relative humidity, and duration in conjunction with an electrical bias configuration specific to the device. 4.1 Typical
27、 temperature, relative humidity and duration Table 1 Temperature, relative humidity and duration requirements Temperature a (dry bulb) C Relative humidity a % Temperature b (wet bulb) C Vapour pressure b kPa Duration c h 130 2 85 5 124,7 230 96 ( 0 2 ) 110 2 85 5 105,2 122 264 ( 0 2 ) NOTE 1 For par
28、ts that reach absorption equilibrium in 24 h or less, the HAST test is equivalent to at least 1 000 h at 85 C/85 % RH. For parts that require more than 24 h to reach equilibrium at the specified HAST condition, the time should be extended to allow parts to reach equilibrium. NOTE 2 Caution: For plas
29、tic-encapsulated micro-circuits, it is known that moisture reduces the effective glass transition temperature of the molding compound. Stress temperatures above the effective glass transition temperature may lead to failure mechanisms unrelated to standard 85 C/85 % RH stress. a Tolerances apply to
30、the entire useable test area. b For information only. c The test conditions are to be applied continuously except during any interim readouts when devices should be returned to stress within the time specified in 5.5. The 96 h and 264 h test durations were selected to be at least equivalent 1 000 h
31、of 85 C/85 % RH stress using a worst case activation energy of E a= 0,65 eV. Page4 EN607494:2002067-944 EI:C0022 5 4.2 Biasing guidelines Apply bias according to the following guidelines: a) Minimize power dissipation. b) Alternate pin bias as much as possible. c) Distribute potential differences ac
32、ross chip metallization as much as possible. d) Maximize voltage within operating range. NOTE The priority of the above guidelines depends on mechanism and specific device characteristics. e) Either of two kinds of bias can be used to satisfy these guidelines, whichever is more severe: 1) Continuous
33、 bias The d.c. bias shall be applied continuously. Continuous bias is more severe than cycled bias when the die temperature is 10 C higher than the chamber ambient temperature or, if the die temperature is not known when the heat dissipation of the DUT is less than 200 mW. If the heat dissipation of
34、 the DUT exceeds 200 mW, then the die temperature should be calculated. If the die temperature exceeds the chamber ambient temperature by more than 5 C, then the die temperature rise above the chamber ambient should be included in reports of test results since acceleration of failure mechanisms will
35、 be affected. 2) Cycled bias The d.c. voltage applied to the devices under test shall be periodically interrupted with an appropriate frequency and duty cycle. If the biasing configuration results in a temperature rise above the chamber ambient, T ja , exceeding 10 C, then cycled bias, when optimize
36、d for a specific device type, will be more severe than continuous bias. Heating as a result of power dissipation tends to drive moisture away from the die and thereby hinders moisture related failure mechanisms. Cycled bias permits moisture collection on the die during the off periods when device po
37、wer dissipation does not occur. Cycling the DUT bias with a 50 % duty cycle is optimal for most plastic encapsulated microcircuits. The period of the cycled stress should be 2 h for packages 2 mm in thickness and 30 min for packages 2 mm in thickness. The die temperature, as calculated on the basis
38、of the known thermal impedance and dissipation should be quoted with the results whenever it exceeds the chamber ambient by 5 C or more. 4.3 Choosing and reporting Criteria for choosing continuous or cyclical bias, and whether or not to report the amount by which the die temperature exceeds the cham
39、ber ambient temperature, are summarized in table 2. Table 2 Bias and reporting requirements T ja Cyclical bias Report T ja T ja 5 C, or power per DUT 200 mW No No ( T ja 5 C or power per DUT 200 mW), and T ja 10 C No Yes T ja 10 C Yes Yes Page5 EN607494:2002067-944 EI:C0022 6 5 Procedure The test de
40、vices shall be mounted in a manner that exposes them to a specified condition of temperature and humidity with a specified electrical biasing condition. Exposure of devices to excessively hot, dry ambient or conditions that result in condensation on devices and electrical fixtures shall be avoided,
41、particularly during ramp-up and ramp-down. 5.1 Ramp-up The time to reach stable temperature and relative humidity conditions shall be less than 3 h. Condensation shall be avoided by ensuring that the test chamber (dry bulb) temperature exceeds the wet-bulb temperature at all times, and that the rate
42、 of ramp up shall not be faster than a rate which ensures that the temperature of any DUT does not lag below the wet bulb temperature. The dry- and wet-bulb temperature set points shall be maintained so that the relative humidity is not less than 50 % after significant heating begins. In a dry labor
43、atory, the chamber ambient may initially be drier than this. 5.2 Ramp-down The first part of ramp-down to a slightly positive gauge pressure (a wet bulb temperature of about 104 C) shall be long enough to avoid test artifacts due to rapid depressurization but shall not exceed 3 h. The second part of
44、 ramp-down from a wet bulb temperature of 104 C to room temperature shall occur with the chamber vented. There is no time restriction and forced cooling of the vessel is permitted. Condensation on devices shall be avoided in both parts of the ramp down by ensuring that the test chamber (dry bulb) te
45、mperature exceeds the wet-bulb temperature at all times. Ramp-down should maintain the moisture content of the molding compound encapsulating the die. Therefore, the relative humidity shall not be less than 50 % during the first part of the ramp down (see 5.1). 5.3 Test clock The test clock starts w
46、hen the temperature and relative humidity reach the set points and stops at the beginning of ramp-down. 5.4 Bias Bias application during ramp-up and ramp-down is optional. Bias should be verified after devices are loaded, prior to the start of the test clock. Bias should also be verified after the t
47、est clock stops, but before devices are removed from the chamber. 5.5 Readout An electrical test shall be performed not later than 48 h after the end of ramp-down. NOTE For intermediate readouts, devices should be returned to stress within 96 h of the end of ramp down. The rate of moisture loss from
48、 devices after removal from the chamber can be reduced by placing the devices in sealed moisture barrier bags (without desiccant). When devices are placed in sealed bags, the “test window clock” runs at one-third of the rate of devices exposed to the laboratory ambient. Thus the test window can be e
49、xtended to as much as 144 h and the time to return to stress to as much as 288 h by enclosing the devices in moisture-proof bags. Page6 EN607494:2002067-944 EI:C0022 7 5.6 Handling Suitable hand-covering shall be used to handle devices, boards and fixtures. Contamination control is important in any highly-accelerated moisture stress test. 6 Failure criteria A
