Advanced Packaging

Advanced Packaging

Flip Chip, Wafer level and 3D memories

CSP, BGA, PoP, Fan in, Fan out

Flip Chip CSP

Flip chip means flipping over the chip to connect with the substrate or leadframe. Flip chip uses solder or bumps like copper pillar for interconnection other than conventional wire bonding. The I/O pads can be distributed all over the surface of the chip, thus the chip size can be shrunk with an optimized circuit path. The absence of a bonding wire also help reduce signal inductance. The key features of Flip Chip packages:

  • Enhanced electrical performance. It provides a shorter path between die and substrate and eliminates the z-height impact of wire bond loops.
  • Increased routing/signal density with small size. Coupled with copper pillar bumped die, flip chip technology could reduce layer count and cost applying fine line/space substrate routing and bump pitch.
  • High Manufacture Efficiency. The package is processed in a strip format and all the bonding is completed in one process wafer bumping.
  • Direct Heat dissipation path. An integrated heat spreader and external heat sink can be directly applied to remove heat.

FCCSP (Flip Chip Chip Scale Package) offers chip scale capacity for I/Os around 200 or less. FCCSP provides better protection for chip and better solder joint reliability compared with direct chip attach (DCA) or chip on board (COB).  FCCSP features thin and small profile, and lightweight packages.

 

KEY FEATURES
  • Suitable for low and high-frequency applications
  • Electroplated Pb-free or Cu pillar bumps
  • Coreless, thin core, laminate, and molded substrate construction
  • Bare die, over-molded, exposed die molded constructions
  • Molded underfill (MUF) or Capillary underfill (CUF) options
  • BGA ball pitches down to 0.1 mm scale
  • Bump pitches with Cu pillar down to 0.01mm scale
  • Package thicknesses down to 0.35 mm
  • Accommodates package sizes from 1×1 mm2 to 25×25 mm2
  • Heat spreader attach available for high-power devices
  • Bottom-side chip attach available for Antenna in Package (AiP) applications
 
 
 
APPLICATIONS
  • Mobile processor (smart phones, tablet, wearable electronics); consumer and automotive.
  • Chipsets for peripheral IC, RF, PMIC, Sensors/MEMS, connectivity
RELIABILITY
  • Moisture Sensitivity Level: JEDEC Level 3@260°C
  • Temperature Cycling Test: -55°C/125°C, 1000 cycles 
  • High Temperature Storage: 150°C, 1000hrs
  • Highly Accelerated Stress Test: 130°C, 85%RH, 2 atm, 96 hrs 

The above are typical condition numbers.

Overmold For FCCSP

There are two ways of overmolding for FCCSP. One is using capillary underfills (CUF), the other one is using epoxy molding compound to substitute underfill (MUF) for lower cost, improve the thermal performance and 2nd level reliability.

Product Recommendation For FCCSP Overmolding
Semicondutor Capillary Underfill (CUF) Board Level Underfill Epoxy Molding Compound Mold Underfill (MUF)

LOCTITE ECCOBOND NCP5209

LOCTITE ABLESTIK NCF218 

LOCTITE ECCOBOND UF8830S

LOCTITE ECCOBOND FP4526

UF8828

FP4511

FP4549 (HT)

Hysol GR920 Series
  • Bump protection of flip-chip devices, with bump pitches less than 100 µm and gaps less than 40 µm
  • Enables fine pitch, narrow gap Cu pillar TSV, Die to die & Die to substrate
  • Achieves MSL L3/L2A and passes all reliability requirements
  • Excellent wettability to different substrates
  • Mechanical reinforcement and improve the thermal cycling performance.
  • Absorb the CTE mismatch between the die and the substrate the die is placed on.
  • Distribute stress across the surface of the die or the substrate instead of being concentrated in the solder balls, especially during thermal cycling.
  • For capillary flow on flip chip applications with excellent reliability
  • Excellent narrow space filling with ultra-fine filler cut (20um)
  • Meet MSL2~3 @260°C requirements
  • Outstanding warpage control (unit warpage<80um)
  • Meet UL94 V-0 flammability at 1/8 inch thickness
  • Good reliability performance on advanced packaging 

 

 

Mold Underfill Epoxy Molding Compound GR920

 

Property / Product Unit of Measure Hysol GR920 H4 Hysol GR920 Q2 Hysol GR910 M12 Hysol GR910 L20 Hysol GR920 A1
UNCURED PROPERTIES
Epoxy Type   MAR MAR/MF MAR/BP MAR/MF BP
Hardener Type   MAR MAR/MF MAR MAR/MF PN/MF
Filler cut µm 20 20 20 20 20
Filler content % 84 85 88.5 88 87.5
Filler Type   Spherical Spherical Spherical Spherical Spherical
Hot Plate Gel time, @ 175°C s 34 39 37 34 46
Spiral Flow @ 175°C inch 60 56 39 36 66
Halogen-free (Green)  
TYPICAL CURED PROPERTIES
Glass Transition Temperature, TMA °C 102 138 120 158 150
Coefficient of Thermal Expansion (CTE)            
   Alpha1, TMA ppm/°C 14 12 10 9 9
   Alpha2, TMA ppm/°C 43 45 35 33 34
Glass Transition Temperature, DMA °C 113 146 127 156 151
Flexural Strength @25°C MPa 125 146 120 154 138
Flexural Modulus @25°C MPa 13500 15500 19500 17800 24000
Modulus by DMA @25°C Mpa 21000 20700 24000 25914 24000
Modulus by DMA @175°C Mpa 350 1200 950 2119 2000
Modulus by DMA @260°C Mpa 235 650 650 1203 1100
Water Absorption, 24hr PCT % - - - 0.37 0.38
Mold Shrinkage PMC % 0.36 0.26 0.13 0.20 0.19
Shore D Hardness - 76 77 76 81 80

 

Board-Level Underfills for CSP

They are used for mechanical reinforcement and to improve the thermal cycling performance. These underfills are used to absorb the CTE mismatch between the die and the substrate the die is placed on. They increase the reliability by distributing stress across the surface of the die or the substrate instead of being concentrated in the solder balls, especially during thermal cycling.

There are three main underfill types:

 

1. Capillary Underfill

  • Dispense material along edge(s), completely flows under the component and fills the complete space
  • Improved thermal and mechanical reliability

2. Partial Underfill - Corner Bond

  • Dispensed before reflow
  • Dispense dots or “L” shape only at the corners
  • Small improvement in mechanical reliability, not in thermal reliability

3. Partial Underfill - Edge Bond

  • Dispense after reflow 
  • Only covers corner fillets 
  • Small improvement in mechanical reliability, not in thermal reliability
  • Can be UV or thermal Cure

Recommended products:

CUF (Capillary)

  • UF8830S,
  • UF8828,
  • FP4511,
  • FP4549(HT),

NCP (Pre-Applied)

  • FP5201,
  • NCP5209