3. Objective
● To discuss and understand the various packaging
technologies.
○ WCSP package
○ PBGA package etc
● Learn advantages and disadvantages of different
packaging types.
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4. Package Overview
● Development of IC package is a Dynamic technology.
● From mobile telecommunication and satellite
broadcasting to aerospace and automotive applications
each imposes its own demands on electronic package.
● To meet such diverse range of requirements, IC package
range encompasses over 30 different types.
● An overview of this range is shown in fig. 1
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7. Through-Hole mount Package
● Refers to the mounting scheme that involves the use of
leads on the components that are inserted into holes
(PTH - Plated Through-Hole) drilled in printed circuit
boards (PCB) and soldered to pads on the opposite side.
● Provides strong mechanical bonds when compared to
surface-mount techniques, the additional drilling required
makes the boards more expensive to produce.
● These techniques are now usually reserved for bulkier
components such as electrolytic capacitors, that require
the additional mounting strength.
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9. Surface mount Package
● In SMT the components are mounted directly onto the
surface of printed circuit boards.
● It has largely replaced the through-hole technology.
● SMT component is usually smaller than its through-hole
counterpart because it has either smaller leads or no
leads at all. It may have short pins or leads of various
styles, flat contacts, a matrix of solder balls (BGAs).
● Advantages
● Smaller components.
● Fewer holes need to be drilled through abrasive boards.
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10. Surface mount Package
● Components can be placed on both sides of the circuit
board.
● Lower resistance and inductance at the connection......
● Disadvantages
● The manufacturing processes for SMT are much more
sophisticated than through-hole boards.
● SMDs can't be used directly with breadboards.
● SMDs' solder connections may be damaged by potting
compounds going through thermal cycling.
● And so on....
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11. Chip-Scale Package (CSP)
● CSP is a type of integrated circuit chip carrier.
● Definition, is a single-die, direct surface mountable
package with an area of no more than 1.2 X the original
die area..
● Definition likewise doesn't define how a chip scale
package is to be constructed, so any package that meets
the surface mountability and dimensional requirements of
the definition is a CSP, regardless of structure. For this
reason, CSP's come in many forms - flip-chip, wire-
bonded, ball grid array, leaded, etc.
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12. Wire-Bonded BGA
● BGA is an acronym for Ball Grid array, as the name
suggests its array of balls aligned to grids.
● Bond pads from top level layout padring are stitched to
external pad frame with Gold Bond Wires.
● Further these pins are connected to balls through
conductor traces on interpose substrate.
Fig. 4 :Wire bond
BGA Package
(cross section)
IC PACKAGING
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14. Flip Chip - BGA
● In Flip Chip BGA the chip/die is flipped, bond pads in
padring layout are connected to external ball grid array
via conductor traces on layered substrate.
● During packaging solder bumps are formed on bondpads
which align and make contact with conductor traces when
flipped.
● Flip-chip packaging techniques connect die bond pads to
a package substrate without using wirebonds. The
bumped die is placed on the package substrate where the
bumps connect to the package pins/balls.
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15. Flip Chip - BGA
Fig. 7 :Flip chip BGA construction and
Substrate cross section
Fig. 8 :In this gold stud bump, the gold ball has
been pressed flat on the bond pad, with the
wire stub protruding from the top of the bump.
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16. Flip Chip - BGA
● Advantages
● Lower inductance power planes support high frequency
designs
● Supports higher pin counts than wirebond packages
● Improved current distribution providing more ability to
minimize IR drops (power is distributed through top metal
layer metal bumps)
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17. Flip Chip - BGA
Fig. 9 :Difference between Wire Bond CSP and FC
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18. Wafer Level Chip-Scale Package
(WL-CSP)
● In this type of technology packaging is done at the Wafer
level, and then dicing is performed .
Fig. 10 :Comparison between Conventional CSP and WLCSP
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19. Wafer Level Chip-Scale Package
● WLP allows direct connection, without wires, to a printed
circuit board by inverting the die and connecting by solder
balls.
● WLP chips are manufactured by building up the package
interconnect structure directly on the silicon circuit
substrate.
● A dielectric repassivation polymer film is applied over the
active wafer surface. This film provides both mechanical
stress relief for the ball attachment, and electrical isolation
on the die surface.
● Here CSP can be expanded as Chip-SIZE Package.
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21. Wafer Level Chip-Scale Package
● Wafer level package is different from FC, as FC requires
the presence of Interposer substrate .
Interposer
Substrate
FC-BGA WLCSP
Fig. 12 :Comparison between WLCSP and FC
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22. Wafer Level Chip-Scale Package
Evolution of Silicon Wafer in size
Fig. 13 :Evolution of Silicon wafer in size
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23. Wafer Level Chip-Scale Package
● Advantages of WLP
● WLP are a small package size, a minimized IC to PCB
inductance and shortened manufacture cycle time.
● Lighter weight and thinner package profile due to
elimination of lead frame and molding compound.
● No under-fill required. Economical.
● Draw backs : Very high I/O IC’s would require very small
solder balls on a very tight pitch. Requires very high
density PCB to interconnect-expensive.
● All the IC’s (good and bad) are packaged at the wafer level
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