EMI SHIELD

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EMI System

Today, wireless system mounted on SMART Phone was increased for high performance. However, it is easy to cause electromagnetic noise on the
wireless system because the built-in clock circuit frequency and data transfer rate increased. The failure of downsizing and reducing module height is
cause of using a board level “Can shield” method in order to block the noise. New technology has appeared for shielding the semiconductor package
itself in order to solve this problem. PCB substrate can be simplified by package level EMI shielding. It also has the advantage that self-shielded semiconductor package can be placed anywhere. CNI Technology has developed In-line sputtering system that is able to form the EMI shield.

Among the EMI shielding method at the package level, there are three most promising conformal shielding techniques, sputtering, plating,
and painting. Sputtering is relatively possible to form a dense EMI shield film since depositing a shield in vacuum. In addition, it is easy to adjust thickness and has an advantage of high yield.

Sputtering Plating Painting(Spray Coating)
Mvaterials Conductive materials : Cu
Passivation materials : SUS, Ni
Seed layer : Cu
Electrolytic Cu, Ni
Conductive material : Ag, Ag/Cu
Based material : Epoxy, Silicon, Acrylic
Film Thickness ~ 10 um ~ 30 um ~ 100 um
Thickness Control Controllable Variational Variational
Environment VOCs1) Free VOCs Free VOCs
Backside Masking Not necessary Necessary Necessary
Shielding Life Long duration Long duration Short duration
Consumable Materials Target, Process gas Cu, Ni electrolyte Ag, Cu Paint
Yield > 98% N/A N/A
Process Flow

1) VOCs : Volatile Organic Compounds

Step coverage

SIGMA1000™ is possible to form thin film over 50% step coverage by controlling tray rotation and sputtering angle. With high
step coverage, it maximizes the target utilization and it improves throughput by shortening the process time.

Section direction Top thickness Side thickness

Full automation system

SIGMA1000™is optimized for the production process by full automation system. Beyond the existing limit on the tape handling
method, full automation system was realized by developing the easy package handling materials(H-VAMs™).

High throughput

SIGMA1000™ maximizes throughput by minimizing the gap between packages within the range with no influence of step
coverage. In addition, by minimizing the tact time, UPH (unit per hour) has been improved more than twice compared to existing
equipment.

Adhesion property

Through plasma treatment, SIGMA1000™ removes impurities from the surface of semiconductor packages and improves an
adhesion between EMI shield layer and semiconductor package molding material. Physically, plasma treatment is applied to
increase surface roughness and surface area. And chemically, surface energy is increased by effect of active oxygen increase on
surface, ion concentration decrease, carbon atom decrease, etc. The change of surface energy can be measured as the contact
angle.

  Before plasma treatment After plasma treatment
AFM Image
Contact angle