MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第113页

MIL-STD-883F METHOD 1018.4 18 June 2004 3 Surfac e conduct ivit y sensor s may not be us ed in metal packages without external pac kage wall insul ation. W hen used, the sensor shall be the c oolest surf ace in t he cavi…

MIL-STD-883F

METHOD 1018.4

18 June 2004

(5) Calibration check

. The system calibration shall be checked on the day of test prior to any testing. This

shall include checking the calibration by in-letting a 5000 ppmv ±20% moisture calibration sample of the

required volumes and comparing the result with the calibration sample. The resulting moisture reading

shall be within 250 ppmv of the moisture level in the calibration sample. Calibration performed on the

day of test prior to any testing may be substituted for the calibration check.

b. A vacuum opening chamber which can contain the device and a vacuum transfer passage connecting the device to

the mass spectrometer of 2.1a. The system shall be maintained at a stable temperature equal to or above the

device temperature. The fixturing in the vacuum opening chamber shall position the specimen as required by the

piercing arrangement of 2.1c, and maintain the device at 100°C ±5°C for a minimum of 10 minutes prior to

piercing.

Note: A maximum 5-minute transfer time from prebake to hot insertion into apparatus shall be allowed. If 5

minutes is exceeded, device shall be returned to the prebake oven and the prebake continued until device reaches

100 °C ±5 °C.

For initial certification of systems or extension of suitability, device temperature on systems using an external

fixture shall be characterized by placing a thermocouple into the cavity of a blank device of similar mass, internal

volume, construction and size. This shall be a means for proving the device temperature has been maintained at

100 °C ± 5 °C for the minimum ten minutes. This also applies to devices prebaked in an external oven but tested

with the external fixture to adjust for any temperature drop during the transfer. These records shall be maintained

by the test laboratory.

c. A piercing arrangement functioning within the opening chamber or transfer passage of 2.1b, which can pierce the

specimen housing (without breaking the mass spectrometer chamber vacuum and without disturbing the package

sealing medium), thus allowing the specimen's 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

should be locally thinned by abrasion to facilitate localized piercing.

2.2 Procedure 2

. (Procedure 2 measures the water-vapor content of the device atmosphere by integrating moisture

picked up by a dry carrier gas at 50°C.) The apparatus for procedure 2 shall consist of:

a. An integrating electronic detector and moisture sensor capable of reproducibly detecting a water-vapor content of

300 ±50 ppmv moisture for the package volume being tested. This shall be determined by dividing the absolute

sensitivity in micrograms H

0 by the computed weight of the gas in the device under test, and then correcting to

ppmv.

b. A piercing chamber or enclosure, connected to the integrating detector of 2.2a, which will contain the device

specimen and maintain its temperature at 100°C ±5°C during measurements. The chamber shall position the

specimen as required by the piercing arrangement. The piercing mechanism shall open the package in a manner

which will allow the contained gas to be purged out by the carrier gas or removed by evacuation. The sensor and

connection to the piercing chamber will be maintained at a temperature of 50°C ±2°C.

2.3 Procedure 3

. (Procedure 3 measures the water-vapor content of the device atmosphere by measuring the response

of a calibrated moisture sensor or an IC chip which is sealed within the device housing, with its electrical terminals available

at the package exterior.) The apparatus for procedure 3 shall consist of one of the following:

a. A moisture sensor element and readout instrument capable of detecting a water-vapor content of 300 ±50 ppmv

while sensor is mounted inside a sealed device.

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 ppmv within the cavity. The chip shall be cooled in a manner such that the chip

surface is the coolest surface in the cavity. The device shall be cooled below dew point and then heated to room

temperature as one complete test cycle.

NOTE: Suitable types of sensors may include (among others) parallel or interdigitated metal stripes on an oxidized

silicon chip, and porous anodized-aluminum structures with gold-surface electrodes.

MIL-STD-883F

METHOD 1018.4

18 June 2004

Surface conductivity sensors may not be used in metal packages without external package wall insulation. When used, the

sensor shall be the coolest surface in the cavity. It should be noted that some surface conductivity sensors require a higher

ionic content than available in ultraclean CERDIP packages. In any case, correlation with mass spectrometer procedure 1

shall be established by clearly showing that the sensor reading can determine whether the cavity atmosphere has more or

less than the specified moisture limit at 100°C.

3. PROCEDURE

. The internal water-vapor content test shall be conducted in accordance with the requirement of

procedure 1, procedure 2, or procedure 3. All devices shall be prebaked for 16-24 hours at 100°C ±5°C prior to hot insertion

into apparatus. External ovens shall have a means to indicate if a power interruption occurs during the prebaking period and

for how long the temperature drops below 100 ±5°C. Devices baked in an external oven which loses power and whose

temperature drops below 100 ±5°C for more than 1 hour shall undergo another prebake to begin a minimum of 12 hours

later.

Note: It is recommended that samples submitted to the labs shall include information about the manufacturing process

including sealing temperature, sealing pressure, sealing gas, free internal cavity volume, lid thickness at puncture site, lid

material, and the location of the puncture site.

3.1 Procedure 1

. The device shall be hermetic in accordance with test method 1014, and free from any surface

contaminants which may interfere with accurate water-vapor content measurement. The internal water-vapor content

laboratory is not required to test for hermeticity in accordance with Test Method 1014 of MIL-STD-883.

After device insertion, the device and chamber shall be pumped down and baked out at a temperature of 100°C ±5°C until

the background pressure level will not prevent achieving the specified measurement accuracy and sensitivity. After

pumpdown, the device case or lid shall be punctured and the following properties of the released gases shall be measured,

using the mass spectrometer:

a. The increase in chamber pressure as the gases are released by piercing the device package. A pressure rise of

less than 50 percent of normal for that package volume and pressurization may indicate that (1) the puncture was

not fully accomplished, (2) the device package was not sealed hermetically, or (3) does not contain the normal

internal pressure.

b. The water-vapor content of the released gases, as a percent by unit volume or parts per million volume (ppmv) of

the total gas content.

c. The proportions (by volume) of the other following gases: N

, He, Mass 69 (fluorocarbons), O

, Ar, H

, CO

, CH

, and other solvents, if available. Calculations shall be made and reported on all gases present greater than

.01 percent by volume. Data reduction shall be performed in a manner which will preclude the cracking pattern

interference from other gas specie in the calculations of moisture content. Data shall be corrected for any system

dependent matrix effects such as the presence of hydrogen in the internal ambient.

3.1.1 Failure criteria

a. A device which has a water-vapor content greater than the specified maximum value shall constitute a failure.

b. A device which exhibits an abnormally low total gas content, as defined in 3.1a, shall constitute a failure, if it is not

replaced. Such a device may be replaced by another device from the same population; if the replacement device

exhibits normal total gas content for its type, neither it nor the original device shall constitute a failure for this cause.

3.2 Procedure 2

. The device shall be hermetic in accordance with test method 1014, and free from any surface

contaminants which may interfere with accurate water-vapor content measurement.

After device insertion into the piercing chamber, gas shall be flowed through the system until a stable base-line value of the

detector output is attained. With the gas flow continuing, the device package shall then be pierced so that a portion of the

purge gas flows through the package under test and the evolved moisture integrated until the base-line detector reading is

again reached. An alternative allows the package gas to be transferred to a holding chamber which contains a moisture

sensor and a pressure indicator. System is calibrated by injecting a known quantity of moisture or opening a package of

known moisture content.

MIL-STD-883F

METHOD 1018.4

18 June 2004

3.2.1 Failure criteria

a. A device which has a water-vapor content (by volume) greater than the specified maximum value shall constitute a

failure.

b. After removal from the piercing chamber, the device shall be inspected to ascertain that the package has been fully

opened. A device package which was not pierced shall constitute a failure, if the test is not performed on another

device from the same population; if this retest sample or replacement is demonstrated to be pierced and meets the

specified water-vapor content criteria, the specimen shall be considered to have passed the test.

c. A package which is a leaker in the purge case will be wet and counted as a failure. In the case of evacuation, a

normal pressure rise shall be measured as in 3.1a.

3.3 Procedure 3

. The moisture sensor shall be calibrated in an atmosphere of known water-vapor content, such as that

established by a saturated solution of an appropriate salt or dilution flow stream. It shall be demonstrated that the sensor

calibration can be verified after package seal or that post seal calibration of the sensor by lid removal is an acceptable

procedure.

The moisture sensor shall be sealed in the device package or, when specified, in a dummy package of the same type. This

sealing shall be done under the same processes, with the same die attach materials and in the same facilities during the

same time period as the device population being tested.

The water-vapor content measurement shall be made, at 100°C or below, by measuring the moisture sensor response.

Correlation with procedure 1 shall be accomplished before suitability of the sensor for procedure 3 is granted. It shall be

shown the package ambient and sensor surface are free from any contaminating materials such as organic solvents which

might result in a lower than usual moisture reading.

3.3.1 Failure criteria

. A specimen which has a water-vapor content greater than the specified maximum value shall

constitute a failure.

4. IMPLEMENTATION

. Suitability for performing method 1018 analysis is granted by the qualifying activity for specific

limits and volumes. Method 1018 calibration procedures and the suitability survey are designed to guarantee ±20 percent

lab-to-lab correlation in making a determination whether the sample passes or fails the specified limit. Water vapor contents

reported either above or below the (water vapor content - volume) range of suitability are not certified as correlatable values.

This out of specification data has meaning only in a relative sense and only when one laboratory's results are being

compared. The specification limit of 5,000 ppmv shall apply to all package volumes, with the following correction factors

permitted to be used, provided they are documented and shown to be applicable:

For package volumes less than .01 cc internal free volume which are sealed while heated in a furnace:

273

, where C

= correction factor (temperature), T

= room temperature (°C), T

= sealing temperature (°C).

For package volumes of any size sealed under vacuum conditions:

C =

, C

= correction factor (pressure), P

= sealing pressure, P

= atmospheric pressure (pressures may be in either

Torr or mm Hg).

The correction factor, if used, shall be applied as follows:

Water Vapor (Corrected) = Water Vapor (Measured) x C

, where C

is the applicable correction factor.

The range of suitability for each laboratory will be extended by the qualifying activity when the analytical laboratories

demonstrate an expanded capability. Information on current analytical laboratory suitability status can be obtained by

contacting DSCC-VQ.