IPC-SM-782A 表面安装设计和焊盘设计标准(带BGA).pdf - 第175页

5.0 LAND PATTERN DIMENSIONS Figure 3 provides the land pattern dimensions for PLCC (Square) components. These numbers represent industry consensus on the best dimensions based on empirical knowl- edge of fabricated land …

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4.0 COMPONENT DIMENSIONS
Figure 2 provides the component dimensions for PLCC
(Square) components.
Component
Identifier
L (mm) S (mm) W (mm) T (mm) A (mm) B (mm)
J
(mm)
H
(mm)
P
(mm)
min max min max min max min max min max min max ref max basic
PLCC-20 9.78 10.03 5.78 6.53 0.33 0.53 1.50 2.00 8.89 9.04 8.89 9.04 7.87 4.57 1.27
PLCC-28 12.32 12.57 8.32 9.07 0.33 0.53 1.50 2.00 11.43 11.58 11.43 11.58 10.41 4.57 1.27
PLCC-44 17.40 17.65 13.40 14.15 0.33 0.53 1.50 2.00 16.51 16.66 16.51 16.66 15.49 4.57 1.27
PLCC-52 19.94 20.19 15.94 16.69 0.33 0.53 1.50 2.00 19.05 19.20 19.05 19.20 18.03 5.08 1.27
PLCC-68 25.02 25.27 21.02 21.77 0.33 0.53 1.50 2.00 24.13 24.33 24.13 24.33 23.11 5.08 1.27
PLCC-84 30.10 30.35 26.10 26.85 0.33 0.53 1.50 2.00 29.21 29.41 29.21 29.41 28.19 5.08 1.27
PLCC-100 35.18 35.43 31.18 31.93 0.33 0.53 1.50 2.00 34.29 34.49 34.29 34.49 33.27 5.08 1.27
PLCC-124 42.80 43.05 38.80 39.55 0.33 0.53 1.50 2.00 41.91 42.11 41.91 42.11 40.89 5.08 1.27
Figure 2 PLCC (Square)
H
LJ
W
T
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
A
B
▼
▼
▼
▼
▼
S
▼
▼
P
L
▼
▼
IPC-782-12-1-2
IPC-SM-782
Subject
PLCC (Square)
Date
5/96
Section
12.1
Revision
A
Page2of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
5.0 LAND PATTERN DIMENSIONS
Figure 3 provides the land pattern dimensions for PLCC
(Square) components. These numbers represent industry
consensus on the best dimensions based on empirical knowl-
edge of fabricated land patterns.
In the table, the dimensions shown are at maximum material
condition (MMC). The least material condition (LMC) should
not exceed the fabrication (F) allowance shown on page 4.
The LMC and the MMC provide the limits for each dimension.
The dotted line in Figure 3 shows the grid placement court-
yard which is the area required to place land patterns and
their respective components in adjacent proximity without
interference or shorting. Numbers in the table represent the
number of grid elements (each element is 0.5 by 0.5 mm) in
accordance with the international grid detailed in IEC publica-
tion 97.
RLP No.
Component
Identifier Z (mm) G (mm) X (mm)
Y (mm) C (mm) D (mm) E (mm)
Placement Grid
(No. of Grid
Elements)ref ref ref ref
790A PLCC-20 10.80 6.40 0.60 2.20 8.60 5.08 1.27 24x24
791A PLCC-28 13.40 9.00 0.60 2.20 11.20 7.62 1.27 30x30
792A PLCC-44 18.40 14.00 0.60 2.20 16.20 12.70 1.27 40x40
793A PLCC-52 21.00 16.60 0.60 2.20 18.80 15.24 1.27 44x44
794A PLCC-68 26.00 21.60 0.60 2.20 23.80 20.32 1.27 54x54
795A PLCC-84 31.20 26.80 0.60 2.20 29.00 25.40 1.27 66x66
796A PLCC-100 36.20 31.80 0.60 2.20 34.00 30.48 1.27 76x76
797A PLCC-124 43.80 39.40 0.60 2.20 41.60 38.10 1.27 90x90
Figure 3 PLCC (Square) land pattern dimensions
Z
G
D
C
Full radius
optional
▼
▼
▼
▼
▼
E
▼
Heel
Y
X
▼
Grid placement
courtyard
C
IPC-782-12-1-3
IPC-SM-782
Subject
PLCC (Square)
Date
5/96
Section
12.1
Revision
A
Page3of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
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
asgiven in the table. These numbers may be modified based
on user equipment capability or fabrication criteria. Compo-
nent tolerance ranges (C
L
,C
S
, and C
W
) are derived by sub-
tracting minimum from maximum dimensions given in Figure
2. The user may also modify these numbers, based on expe-
rience 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
Heel (mm) Toe (mm) Side (mm)
FPC
L
J
H
min J
H
max C
S
J
T
min J
T
max C
W
J
S
min J
S
max
790A 0.10 0.10 0.25 0.37 0.51 0.75 -0.32 0.06 0.20 0.01 0.14
791A 0.10 0.10 0.25 0.40 0.54 0.75 -0.35 0.04 0.20 0.01 0.14
792A 0.10 0.10 0.25 0.36 0.50 0.75 -0.31 0.07 0.20 0.01 0.14
793A 0.10 0.10 0.25 0.39 0.53 0.75 -0.34 0.04 0.20 0.01 0.14
794A 0.10 0.10 0.25 0.35 0.49 0.75 -0.30 0.08 0.20 0.01 0.14
795A 0.10 0.10 0.25 0.41 0.55 0.75 -0.36 0.03 0.20 0.01 0.14
796A 0.10 0.10 0.25 0.37 0.51 0.75 -0.32 0.06 0.20 0.01 0.14
797A 0.10 0.10 0.25 0.36 0.50 0.75 -0.31 0.07 0.20 0.01 0.14
Figure 4 Tolerance and solder joint analysis
Zmax = Lmin + 2J
T
min + T
T
Where:
J
T
min = Minimum toe fillet
T
T
= Combined tolerances
at toe fillet
Gmin = Smax - 2J
H
min - T
H
Where:
J
H
min = Minimum heel fillet
T
H
= Combined tolerances
at heel fillet
Xmax
Xmax = Wmin + 2J
S
min
+ T
S
Where:
J
S
min = Minimum side fillet
T
S
= Combined tolerances
at side fillet
▼
▼
Toe Fillet
1
/2 T
S
Heel Fillet Side Fillet
J
S
max
▼
▼
▼
▼
▼
▼
▼
J
S
min
Lmin
▼
▼
Zmax
▼
▼
1
/2 T
T
J
T
min
Smax
J
H
min
1
/2 T
H
▼
▼
▼
▼
▼
▼
▼
▼
J
T
max
J
H
max
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
▼
Gmin
▼
Wmin
▼
IPC-782-12-1-4
IPC-SM-782
Subject
PLCC (Square)
Date
5/96
Section
12.1
Revision
A
Page4of4
电子技术应用　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ