PoP (package on package) and vapor phase technology
PoP (package on package)
and vapor phase technology
by Dan Coada, EPIC Technologies LLC, Norwalk, Ohio, USA
Increased use of PoP technology is driven technology are not significantly different
The trend toward smaller, by continued product miniaturization. from individual BGAs. Following screen
more densely populated
Smaller products require increased printed printing, the first component is placed.
electronic assemblies is
circuit board assembly (PCBA) density. Then the second component is flux dipped
driving increased use of
Stacking memory is one way to achieve and placed. In some cases, up to two or
package-on-package (PoP)
both goals for enhanced functionality and more BGAs may be stacked. The only
greater packaging density. significant line modification is purchasing
technology ,and electronics
PoP technology is not without manufac- a flux dip module for placement machines.
manufacturing services (EMS)
turing challenges. While the ball grid array Thermal profiling during reflow is the
providers are developing viable (BGA) packages used are well understood, same as boards of similar thermal mass.
manufacturing solutions.
a poor quality process carries a far higher Quality needs to be carefully moni-
cost in terms of rework or scrap, since two tored. Any distortion in the bottom com-
or more BGAs are affected. ponent will be reflected in the components
Placement requirements and process above it.
Keywords: Package on Package,
PoP, Vapor Phase Reflow, Solder
Joint Formation
Figure 1. A 2-D x-ray image of primary and secondary stacked BGAs pre-reflow indicated excellent placement
accuracy.
10 – Global SMT & Packaging – September 2009 www.globalsmt.net
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