IEC 60749-7 pdf download – Semiconductor devices — Mechanical and climatic test methods — Part 7: Internal moisture content measurement and the analysis of other residual gases

IEC 60749-7 pdf download – Semiconductor devices — Mechanical and climatic test methods — Part 7: Internal moisture content measurement and the analysis of other residual gases
1Scope
The purpose of this part of EC 60749 is to test and measure the water vapour and other gascontent of the atmosphere inside a metal or ceramic hermetically sealed device. lt isapplicable to semiconductor devices sealed in such a manner but generally only used for highreliability applications such as military or aerospace. It can be destructive(Methods 1 and 2)or non-destructive (Method 3).
2Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies. For undated references, the latest editionof the referenced document (including any amendments) applies.
IEC 60749-8,Semiconductor devices – Mechanical and climatic test methods – Part 8:sealing 1)
3Test apparatus
The apparatus for testing the internal water vapour content and that of other gases shall be asfollows for the chosen method.
3.1Method 1
Method 1 measures the water vapour content of the device atmosphere by mass spectro-metry.The apparatus for method 1 shall consist of:
a) A mass spectrometer capable of reproducibly detecting the specified moisture content for a given volume package with a factor of ten sensitivity safety margin (i.e. for a specifiedlimit of 5 000 x 10-6 by volume2)，0,01 ml,the mass spectrometer shall demonstrate a500 x 10-6 by volume or less absolute sensitivity to moisture for a package volume of0,01 ml).The smallest volume shall be considered the worst case.The calibration of themass spectrometer shall be accomplished at the specified moisture limit (+20 %) using apackage simulator which has the capability of generating at least three known volumes ofgas ±10 % on a repetitive basis by means of a continuous sample volume purge of knownmoisture content 土10 %.Moisture content shall be established by the standard generationtechniques (i.e. double pressure，divided flow,or cryogenic method). The absolutemoisture shall be measured by a moisture dew point analyzer.The calibration operationshall be performed:
every day for the spectrometer measurement calibration;
every year for the absolute moisture generator (connected to the simulator) versus thenational standards.
Gas analysis results obtained by this method shall be considered valid only in themoisture range or limit bracketed by at least two (volume or concentration) calibrationpoints (i.e.5 000 x 10-6 by volume between 0,01 ml and 0,1 ml or 1 000 x10-6 by volumeto 5 000 x10-6 by volume between 0,01 ml to 0,1 ml).A best fit curve shall be usedbetween volume calibration points.Corrections of sensitivity factors deviating greater than10 % from the mean between calibration points shall be required.
b) A vacuum opening chamber which can contain the device and a vacuum transfer passage
connecting the device to the mass spectrometer of 3.1a). The transfer passage shall bemaintained at 125 C±5 C. The fixturing in the vacuum opening chamber shall positionthe specimen as required by the piercing arrangement of 3.1c) and maintain the device at100 C主5 C for a minimum of 10 min prior to piercing.
c)A piercing arrangement functioning within the opening chamber or transfer passage of
3.1b), which can pierce the specimen housing (without breaking the mass spectrometerchamber vacuum and without disturbing the package sealing medium), thus allowing thespecimen internal gases to escape into the chamber and mass spectrometer.
NOTE A sharp-pointed piercing tool, actuated from outside the chamber wall via a bellows to permit movement,should be used to pierce both metal and ceramic packages. For ceramic packages, the package lid or cover shouldbe locally thinned by abrasion to facilitate localized piercing but care should be taken to ensure that the packageremains hermetic.
3.2Method 2
Method 2 measures the water vapour content of the device atmosphere by integratingmoisture picked up by a dry carrier gas at 50 °C.The apparatus for Method 2 shall consist of:
a) An integrating electronic detector and moisture sensor capable of reproducibly detecting a
water vapour content of 300 ×10-6±50 x10-6 by volume moisture for the package volumebeing tested.This shall be determined by dividing the absolute sensitivity in microgramsH,0 by the computed weight of the gas in the device under test,and then correcting toparts per million by volume (ppmv).
b)Apiercing chamber or enclosure, connected to the integrating detector of 3.2a), which will
contain the device specimen and maintain its temperature at 100 C ± 5 C duringmeasurements.The chamber shall position the specimen as required by the piercingarrangement.The piercing mechanism shall open the package in a manner which willallow the contained gas to be purged out by the carrier gas or removed by evacuation.Thesensor and connection to the piercing chamber will be maintained at a temperature of50 oC±2 oc.
3.3Method 3
Method 3 measures the water vapour content of the device atmosphere by measuring theresponse of a calibrated moisture sensor or an lc chip which is sealed within the devicehousing，with its electrical terminals available at the package exterior. The apparatus forMethod 3 shall consist of:
a) A moisture sensor element and readout instrument capable of detecting a water vapour
content of 300 ×10-6 ±50 ×10-6 by volume while sensor is mounted inside a sealeddevice.
b) Metallization runs on the device being tested isolated by back-biased diodes which when
connected as part of a bridge network can detect 2 000 x10-6 by volume within thecavity. The chip shall be cooled in such a manner that the chip surface is the coolestsurface in the cavity.The device shall be cooled below dew point and then heated to roomtemperature as one complete test cycle.