IPC-TM-650 EN 2022 试验方法--.pdf - 第776页
1 Scope Moisture absorption can cause delam ination or other damage in printed boards subjected to soldering heat. This test is a process control tool to determine both the bulk moisture cont ent and moisture ab sorp t i…
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Number
2.6.27
Subject
Thermal Stress, Convection Reflow Assembly Simulation
Date
2/2020
Revision
B
IPC-TM-650
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1 Scope
Moisture absorption can cause delamination or
other damage in printed boards subjected to soldering heat.
This test is a process control tool to determine both the bulk
moisture content and moisture absorption rate of a printed
board. It may be used to determine whether the specimen
conforms to the monitoring level of the user’s performance
specification, to assist in process development, or for process
control. This test may not provide accurate analytical results
on all specimens, depending on the thickness of the item, the
presence of copper layers or other moisture barriers within the
structure, or the presence of any volatile compounds other
than water. The weight of the specimen is compared before
and after a bake operation. The bake is intended to remove
most of the water (> 90%) from the sample, and the bake time
and temperature specified herein are minimums. To improve
test accuracy, or to prevent heat damage, other bake param-
eters may be as agreed between user and supplier (AABUS).
2 Applicable Documents
Certification of Facilities that Inspect/Test
Printed Boards, Components and Materials
3 Test Specimens
This test may be applied to actual printed boards. If the item
is too large to be weighed easily, a representative sample or
coupon may be used. The sample may be sectioned from a
larger printed board or assembly (e.g., a scrapped item), pro-
vided that the sample represents the features and construc-
tion of the whole. The sample should be sized based on the
mass capacity and physical dimensions of the analytical bal-
ance. If a coupon is used, it must include features and con-
struction similar to the item that it represents, including similar
content and distribution of copper, and must have been sub-
jected to the identical processing environments and condi-
tions. It should be realized that the use of a representative
coupon excised from a larger printed board may result in
exposed laminate edges that will result in a slightly different
absorption rate than the actual printed board.
4 Apparatus
4.1
Circulating air oven capable of maintaining a uniform
temperature of 105 +5 °C/-0 °C (221 +9 °F/-0 °F). Nitrogen
atmosphere (inert) or vacuum is not required, but will promote
drying and improve accuracy of the test.
4.2
Analytical balance capable of determining the test
sample/coupon weight in grams to 4 places of accuracy
(X.XXXX) is required. Precautions
be taken to ensure
that the analytical balance test location is not compromised by
vibration or air drafts. If the test samples are functional printed
circuit boards with embedded active devices, ESD require-
ments appropriate to handling these circuit boards
be
followed. The analytical balance
be calibrated in accor-
dance with IPC-QL-653.
4.3
Tweezers, tongs or equivalent be used to handle
the test sample/coupons to prevent handling contamination.
The tweezers
be cleaned prior to each test sample/
coupon weighing session.
4.4
Gloves be used when handling the test samples/
coupons to prevent handling contamination. The gloves
contribute any contamination material on the test
samples/coupons.
5 Procedure
5.1 Initial Weighing
The weight of the test sample/coupon
be determined to the nearest 0.0001g and recorded.
5.2 Bake
The test sample/coupon be baked for 24
hours at 105 +5 °C/-0 °C (221 + 9 °F/-0 °F), unless AABUS.
The intent of this bake is to remove at least 90% of the
moisture from the sample. Printed boards that are very thick,
have solid copper planes, or that are especially saturated with
moisture (which may be bound deep within inner layers) may
require longer bake times and/or higher temperatures.
5.3 Post-Bake Weighing
An extremely rigid post bake
weighing regimen must be strictly followed to accurately
determine the test sample/coupon absorption rate. The ana-
lytical balance measurement station
be organized to
prevent any interruption of the post bake weighing process.
Procedure:
1. The test sample/coupon
be removed from the circu-
lating oven and transferred immediately (within 2 minutes)
to the analytical balance measurement location.
2. Each test sample/coupon
be placed on the analyti-
cal balance and allowed to dwell for 15 seconds, and then
3000 Lakeside Drive, Suite 309S
Bannockburn, IL 60015-1249
IPC-TM-650
TEST METHODS MANUAL
Number
2.6.28
Subject
Moisture Content and/or Moisture Absorption Rate,
(Bulk) Printed Board
Date
08/2010
Revision
Originating Task Group
Board Storage and handling Subcommittee (D-35)
Association
Connecting
Electronics
Industries
IPC-QL-653
shall
shall
shall
shall
shall
shall
shall
not
shall
Note:
shall
shall
shall
shall
Material
/n
this
Test
Methods
Manual
was
voluntarily
established
by
Technical
Committees
of
I
PC.
This
material
/s
advisory
only
and
"s
use
or
adaptation
，
s
entirely
voluntary.
IPC
disclaims
all
liability
of
any
kind
as
to
the
use,
application,
or
adaptation
of
this
material.
Users
are
also
wholly
responsible
for
protecting
themselves
against
all
claims
or
liabilities
for
patent
infringement.
Equipment
referenced
/s
for
the
convenience
of
the
user
and
does
not
imply
endorsement
by
IPC.
Page
1
of
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the sample/coupon weight be recorded to the near-
est 0.0001 g. Note that the sample/coupon weight will not
settle completely.
These measurements characterize the bulk moisture content
of the test samples. If the moisture absorption rate is desired,
continue with process steps 3 through 5:
3. Measure and record ambient temperature and relative
humidity at the analytical balance measurement station.
4. The test sample/coupons
remain at the analytical
balance measurement station for 15 minutes +1/-0 min-
utes and procedure steps 2-3
be repeated.
5. Repeat step 4, taking measurements at 15 minute inter-
vals, for at least 4 hours.
The ambient temperature and humidity, the frequency
with which ambient conditions are recorded, the measure-
ment intervals between weighings and the number of weigh-
ings may be adjusted AABUS.
5.4 Calculations
Calculate the bulk moisture content using
the following equation:
Moisture Content (%) =
(
(Initial Weight) − (Post−Bake Weight)
(Post−Bake Weight)
)
X 100
Calculate the moisture absorption rate by plotting the bulk
moisture content versus time using the data recorded in Pro-
cedure steps 3 through 5 of 5.3.
Metals do not absorb moisture, and metal content in
the specimen will affect the accuracy of this determination. If
copper or other metals are likely to exceed 20% of the weight
of the specimen, this weight should be determined or esti-
mated, and subtracted from both the Initial Weight and the
Post-Bake Weight in the formula above. This correction factor
be AABUS.
5.5 Report
Report the bulk moisture content or moisture
absorption rate for the sample/coupon.
Number
2.6.28
Subject
Moisture Content and/or Moisture Absorption Rate, (Bulk)
Printed Board
Date
08/2010
Revision
shall
Note:
shall
shall
Note:
shall
IPC-TM-650
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