AN-5026 Datasheet, PDF (1/8 Pages) Fairchild Semiconductor – Using BGA Packages

AN-5026
Fairchild Semiconductor
Application Note
January 2001
Revised September 2001
Using BGA Packages
Introduction
Demanding space and weight requirements of personal
computing and portable electronic equipment has led to
many innovations in IC packaging. Combining the right
interface and logic products with new package technology
can have a significant impact on the capabilities and form-
factor of the end product. Leaded surface mount devices
are constantly pushing the manufacturing capabilities of
leading board manufacturers to finer and finer lead pitch
geometry’s to increase I/O density and reduce board
space.
This requirement has lead to significant interest in the
JEDEC (Joint Electron Device Engineering Council) regis-
tered Fine-Pitch Ball Grid Array (FBGA) package. These
packages are ideally suited to low cost, high volume appli-
cations, where package size and performance is of major
importance. Typical BGA applications include:
1. Notebook computers
2. Personal Digital Assistants (PDA’s)
3. Mobile telephone handsets
4. High density disk drives
5. Camcorders
6. Digital cameras
BGA advantages compared to fine pitch QFP or TSSOP
packages:
1. BGAs are usually smaller.
2. BGAs have larger pitch.
3. BGAs have no fragile leads, that causes yield and
rework problems.
4. Board assembly yields are significantly improved.
5. Board inspection can be reduced.
6. BGAs have better thermal and electrical properties.
7. In many applications, the use of BGA results in signifi-
cant system level cost savings.
Surface Mount vs. BGA
At 0.4 to 0.5mm pin pitch, the race to finer surface mount
lead pitches has hit several technical and economic walls.
Manufacturing anything smaller will significantly impact
PCB yield and push board costs above acceptable levels
for the highly competitive and cost conscious electronics
industry. Avoiding problems such as bent leads and solder
bridging become significant manufacturing challenges.
Additionally, electrical problems such as crosstalk become
a major issue due to the length and close pitch of the leads
on surface mount packages.
Alternatively, BGA packaging uses relatively wide “pad to
pad” pitch rules and when coupled with existing PCB man-
ufacturing processes result in high yields. The “array”
approach improves I/O density and reduces the board
space consumed by the device. Table 1 and Figure 1 show
examples of space savings of BGA over surface mount
packages.
TABLE 1. BGA Space Savings
Compared to Surface Mount Packages
Number
of Bits
36 to 48
32 to 40
18 to 24
16 to 20
TSSOP
> 66%
> 67%
65.50%
61%
TVSOP
> 47%
61%
40%
39%
QVSOP
BQSOP
> 59%
49%
NA
37%
FIGURE 1. 114 Ball BGA vs. Surface Mount
© 2001 Fairchild Semiconductor Corporation AN500543
www.fairchildsemi.com