IPC-SM-782A 表面安装设计和焊盘设计标准(带BGA).pdf - 第83页

1.0 SCOPE Microminiature leadless devices are available to the circuit designer in rectangular form for discrete components such as tantalum capacitors. This subsection provides the component and land pattern dimensions …

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6.0 TOLERANCE AND SOLDER JOINT ANALYSIS
Figure 4 provides an analysis of tolerance assumptions and
resultant solder joints based on the land pattern dimensions
shown in Figure 3. Tolerances for the component dimensions,
the land pattern dimensions (fabrication tolerances on the
interconnecting substrate), and the component placement
equipment accuracy are all taken into consideration.
Figure 4 provides the solder joint minimums for toe, heel, and
side fillets, as discussed in Section 3.3. The tolerances are
addressed in a statistical mode, and assume even distribution
of the tolerances for component, fabrication, and placement
accuracy.
Individual tolerances for fabrication (‘‘F’’) and component
placement equipment accuracy (‘‘P’’) are assumed to be as
given in the table. These numbers may be modified based on
user equipment capability or fabrication criteria. Component
tolerance ranges (C
L
,C
S
, and C
W
) are derived by subtracting
minimum from maximum dimensions given in Figure 2. The
user may also modify these numbers, based on experience
with their suppliers. Modification of tolerances may result in
alternate land patterns (patterns with dimensions other than
the IPC registered land pattern dimensions).
The dimensions for minimum solder fillets at the toe, heel, or
side (J
T
,J
H
,J
S
) have been determined based on industry
empirical knowledge and reliability testing. Solder joint
strength is greatly determined by solder volume. An observ-
able solder fillet is necessary for evidence of proper wetting.
Thus, the values in the table usually provide for a positive sol-
der fillet. Nevertheless, the user may increase or decrease the
minimum value based on process capability.
RLP No.
Tolerance
Assumptions (mm)
Solder Joint
Toe (mm) Heel (mm) Side (mm)
FPC
L
J
T
min J
T
max C
S
J
H
min J
H
max C
WI
J
S
min J
S
max
160 0.2 0.2 0.663 0.32 0.98 0.721 0.02 0.74 0.663 –0.13 0.53
161 0.2 0.2 0.663 0.32 0.98 0.787 0.02 0.81 0.663 –0.18 0.48
162 0.2 0.2 0.663 0.47 1.13 0.970 –0.02 0.95 0.663 –0.13 0.53
163 0.2 0.2 0.663 0.47 1.13 0.773 –0.08 0.70 0.325 0.06 0.39
164 0.2 0.2 0.663 0.52 1.18 0.970 –0.07 0.90 0.490 0.06 0.54
165 0.2 0.2 0.663 0.47 1.13 0.970 –0.02 0.95 0.490 0.05 0.54
166 0.2 0.2 0.663 0.39 1.06 0.758 –0.12 0.64 0.325 0.01 0.33
167 0.2 0.2 0.490 0.46 0.94 0.648 0.17 0.82 0.346 0.03 0.37
168 0.2 0.2 0.583 0.50 1.09 0.837 –0.12 0.72 0.412 –0.11 0.31
169 0.2 0.2 0.663 0.47 1.13 0.894 0.23 1.12 0.346 0.03 0.37
170 0.2 0.2 0.346 0.58 0.92 1.058 0.03 1.09 0.490 –0.14 0.34
171 0.2 0.2 0.583 0.48 1.07 0.837 0.10 0.94 0.412 –0.11 0.31
Figure 4 Tolerance and solder joint analysis
▼
Wmin
Lmin
▼
▼
Zmax
▼
▼
1
/2 T
T
J
T
min
Smax
J
H
min
Xmax
▼
▼
Toe Fillet
1
/2 T
S
▼
▼
▼
Heel Fillet Side Fillet
▼
▼
▼
▼
▼
J
T
max
J
H
max
J
S
max
J
S
min
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
Gmin
▼
▼
1
/2 T
H
▼
▼
▼
IPC-872-8-3-4
IPC-SM-782
Subject
Inductors
Date
8/93
Section
8.3
Revision
Page4of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
1.0 SCOPE
Microminiature leadless devices are available to the circuit
designer in rectangular form for discrete components such as
tantalum capacitors.
This subsection provides the component and land pattern
dimensions for tantalum capacitors along with an analysis of
tolerance and solder joint assumptions used to arrive at the
land pattern dimensions. Basic construction of the inductor is
also covered.
2.0 APPLICABLE DOCUMENTS
See Section 8.0 for documents applicable to the subsections.
3.0 COMPONENT DESCRIPTIONS
A variety of values exist for tantalum capacitors. The following
sections describe the most common types.
3.1 Basic Construction
See Figure 1.
3.1.1 Termination Materials
End terminations should be
solder coated with a tin/lead alloy. The solder should contain
between 58 to 68% tin. Solder may be applied to the termi-
nation by hot dipping or by plating from solution. Plated sol-
der terminations should be subjected to a post-plating reflow
operation to fuse the solder. The tin/lead finish should be at
least 0.0075 mm [0.0003 in] thick.
The termination shall be symmetrical, and shall not have nod-
ules lumps, protrusions, etc., that compromise the symmetry
or dimensional tolerances of the part. The end termination
shall cover the ends of the components, and shall extend out
to the top and bottom of the component.
Most common termination materials include palladium-silver
alloy, silver, and gold. Solder finish applied over precious
metal electrodes shall have a diffusion-barrier layer between
the electrode metallization and the solder finish. The barrier
layer should be nickel or an equivalent diffusion barrier, and
should be at least 0.00125 mm [0.00005 in] thick.
3.1.2 Marking
Parts are available with or without marked
capacitance values.
3.1.3 Carrier Package Format
Bulk rods, 8 mm tape/4
mm pitch is preferred for best handling. Tape and reel speci-
fications provide additional requirements.
3.1.4 Resistance to Soldering
Parts should be capable of
withstanding five cycles through a standard reflow system
operating at 215°C. Each cycle shall consist of 60 seconds
exposure at 215°C. Parts must also be capable of withstand-
ing a minimum of 10 seconds immersion in molten solder at
260°C.
IPC-782-8-4-1
Figure 1 Tantalum capacitor construction
or
IPC-SM-782
Surface Mount Design
and Land Pattern Standard
Date
5/96
Section
8.4
Revision
A
Subject
Tantalum Capacitors
Page1of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
4.0 COMPONENT DIMENSIONS
Figure 2 provides the component dimensions for tantalum capacitors.
Component
Identifier (mm)
L (mm) S (mm) W1 (mm) W2 (mm) T (mm)
H1
(mm)
H2
(mm)
min max min max min max min max min max min max
3216 3.00 3.40 0.80 1.74 1.17 1.21 1.40 1.80 0.50 1.10 0.70 1.80
3528 3.30 3.70 1.10 2.04 2.19 2.21 2.60 3.00 0.50 1.10 0.70 2.10
6032 5.70 6.30 2.50 3.54 2.19 2.21 2.90 3.50 1.00 1.60 1.00 2.80
7343 7.00 7.60 3.80 4.84 2.39 2.41 4.00 4.60 1.00 1.60 1.00 3.10
Figure 2 Tantalum capacitor component dimensions
S
L
H
1
H
2
W
1
W
2
T
2 Places
IPC-782-8-4-2
IPC-SM-782
Subject
Tantalum Capacitors
Date
5/96
Section
8.4
Revision
A
Page2of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ