IPC-SM-782A-表面贴装焊盘图形设计标准.pdf.pdf - 第145页
1.0 INTRODUCTION This section covers land patterns for components with gull- wing leads on four sides. Each subsection contains informa- tion in accordance with the following format: 1.0 Scope 2.0 Applicable Documents 3.…
6.0 TOLERANCE AND SOLDER JOINT ANALYSIS
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.
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
Heel (mm) Toe (mm) Side (mm)
FPC
S
J
H
min J
H
max C
L
J
T
min J
T
max C
W
J
S
min J
S
max
480-487A 0.10 0.10 0.38 0.31 0.51 0.68 -0.32 0.03 0.13 -0.01 0.11
490-497A 0.10 0.10 0.38 0.27 0.48 0.68 -0.28 0.07 0.13 -0.01 0.11
500-507A 0.10 0.10 0.38 0.24 0.44 0.68 -0.27 0.10 0.13 -0.01 0.11
510-517A 0.10 0.10 0.38 0.30 0.51 0.68 -0.31 0.04 0.13 -0.01 0.11
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-782-10-1-4
IPC-SM-782
Subject
SOJ
Date
5/96
Section
10.1
Revision
A
Page6of6
1.0 INTRODUCTION
This section covers land patterns for components with gull-
wing leads on four sides. Each subsection contains informa-
tion in accordance with the following format:
1.0 Scope
2.0 Applicable Documents
3.0 General Component Description (Figure 1)
4.0 Component Dimensions (Figure 2)
5.0 Land Pattern Dimensions (Figure 3)
6.0 Tolerance and Solder Joint Analysis (Figure 4)
The following is the table of contents for this section:
2.0 APPLICABLE DOCUMENTS
The following documents, of the issue in effect on the revision
date of this section, form a part of this specification to the
extent specified herein.
2.1 Electronic Industries Association (EIA)
1
EIA-481-A Taping of Surface Mount Components for Auto-
matic Placement
EIA-481-3 32 mm, 44 mm, and 56 mm Embossed Carrier
Taping of Surface Mount Components for Automated Han-
dling
JEDEC Publication 95 Registered and Standard Outlines for
Solid State and Related Products:
MO 108, issue ‘‘A,’’ dated 10/90
MO 112, issue ‘‘A,’’ dated 8/90
MO 136, issue ‘‘A,’’ dated 8/92, now MS-026
MO 143, issue ‘‘A,’’ dated 3/93, now MS-029
2.2 Electronic Industries Association of Japan (EIAJ)
EIAJ-ED-7404
General Rules for the Preparation of Outline
Drawings of Integrated Circuits
2.3 International Electrotechnical Commission (IEC)
2
IEC 97 Grid Elements
3.0 General Information
3.1 General Component Description
The four-sided gull
wing family is characterized by gull wing leads on four sides of
a square or rectangular package. The family includes both
molded plastic and ceramic case styles. The acronyms PQFP,
Plastic Quad Flat Pack and CQFP, Ceramic Quad Flat Pack,
are also used to describe the family.
There are several lead pitches within the family from 1.0 mm
to 0.30 mm. High lead-count packages are available in this
family that accommodate complex, high lead-count chips.
3.2 Marking The PFQP and CQFP families of parts are
generally marked with manufacturers part numbers, manufac-
turers name or symbol, and a pin 1 indicator. Some parts may
have a pin 1 feature in the case shape instead of pin 1 mark-
ing. Additional markings may include date code/
manufacturing lot and/or manufacturing location.
3.3 Carrier Package Format Components may be pro-
vided in tube but packaging tray carriers are preferred for best
handling and high volume applications. Bulk packaging is not
acceptable because of lead coplanarity required for place-
ment and soldering.
3.3 Process Considerations PQFP and CQFP packages
are normally processed by solder reflow operations.
High lead-count fine pitch parts may require special process-
ing outside the normal pick/place and reflow manufacturing
operations.
Separate pick/place, excise, and reflow processes are some-
times used as an alternate to normal SMT processes.
1. Application for copies should be addressed to Global Engi-
neering Documents, 1990 M St. N.W., Washington, DC
20036.
2. Application for copies should be addressed to IEC, 3 rue
de Varembe, PO Box 131 - 1211 Geneva 20, Switzerland
IPC-SM-782
Surface Mount Design
and Land Pattern Standard
Date
8/93
Section
11.0
Revision Subject
Components with
Gullwing Leads on Four
Sides
Page1of2
Page Intentionally Left Blank
IPC-SM-782
Subject
Components with Gullwing Leads on Four Sides
Date
8/93
Section
11.0
Revision
Page2of2