Page 261 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

2 Temperature Settings:
For soldering irons and preheaters, precise temperature control is paramount. Different solder alloys and component
types require specific temperatures to achieve reliable solder joints. Most soldering irons and preheaters allow
you to adjust the temperature according to the needs of the particular component you’re working with.
BGA Components and Their Soldering Technologies in SMT Assembly.
Classifications and Properties of BGA Components

• Classifications of BGA Components:
Based on different packaging materials, BGA components can be classified into the following types: PBGA (plastic
ball grid array), CBGA (ceramic ball grid array), CCGA (ceramic column grid array), TBGA (tape ball grid array)
and CSP (chip-scale package.
• Properties of BGA Components
The leading properties BGA components hold include:
a I/O lead pitch is so large that more I/O count can be held within the same area.
b Higher packaging reliability, lower defect rate of solder joints and higher reliability of solder joints.

c Alignment of QFP (quad flat package) chips is usually achieved by visual observation carried out by operators
and it’s difficult for alignment and soldering. However, it’s easier to implement alignment and soldering on BGA
components due to relatively large pin pitch.
d It’s easier to carry out solder paste printing through stencil on BGA components.
e BGA pins are steady with better flatness than QFP package because flatness error can be automatically
compensated between chip and PCB (printed circuit board) after solder ball melting.
f During soldering process, tension between solder joints will lead to high self-alignment that allows mounting
precision error of 50%.

g Featuring excellent electrical properties, BGA components make it possible to obtain excellent frequency
merits.
h BGA components perform better in terms of thermal dissipation.
Naturally, apart from advantages, BGA components also feature disadvantage. One leading disadvantage is
that it’s difficult to inspect quality of solder joints, which depends on AXI (automated X-ray inspection) and AOI
(automated optical inspection) equipment that are capable of observing solder ball collapse. Of course, inspection
cost and difficulty rise as well.
Storage and Application Environment of BGA Components:
BGA components are a type of highly humidity and thermal-sensitive components, so they should be stored
in the dry environment with constant temperature. Moreover, operators should rigorously conform to operation
technology process to stop components from bad effect prior to assembly. Generally speaking, the optimal
storage environment for BGA components is within the temperature range from 20°C to 25°C with humidity less
than 10%RH. Furthermore, they should best be stored by nitrogen gas.
Generally, after BGA component packages are opened, they should never be exposed to the air for long time
during assembly and soldering process to stop components from leading to soldering quality reduction due to
their low quality. Once packages of BGA components are opened, they have to be used up within 8 hours in
the operation environment of ≤30°C/60%RH. When components are stored in nitrogen, application time can be
prolonged to some extent.

It’s extremely common to see that BGA components fail to be used up once their packages are opened during
SMT (surface mount technology) assembly. BGA components have to be baked prior to their applications next
time to capture their excellent solderability. Baking temperature usually maintains at 125°C. Relationship between
baking time and package thickness can be summarized in below table.
BGA Component Soldering Technologies:

BGA component assembly technologies are fundamentally compatible with SMT. Leading soldering phases come
as solder paste printing on pad array by stencil and BGA components alignment to pad array, reflow soldering
of BGA components. In the rest of this article, a brief introduction will be provided on PBGA soldering process.

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CITS : E & H - Electronics Mechanic - Lesson 130 - 145