Question

IC Packaging. Select the correct answer for each

a) Why are conductive bumps added to die in many packaging technologies?

-To provide dielectric bonds when solder overtures aren't sufficiently reliable

-To provide short distance, secure interconnects to another die or a substrate, with very small spacing

-Something is needed to hold the wires away from the die

-To provide something to melt when going through the solder reflow process

-Bumps help the molding compound to adhere to the back of the lead frame housing, even when 220V is applied

b) Why are some semiconductor products shipped in Tape and Reel instead of in black plastic trays?

-It's easier to ship reels on spools than to ship cardboard boxes

-Tape and Reel spllos can load directly into some of the automated circuit board populating equipment

-Wafers fit more easily into tape and reel than into other types of shipping containers

-It's easier to count the circuits on a reel than in a tray

-Tape tends to prevent solder creep, while Reel prevents outgassing from the die

c) What occurs in the solder reflow process?

-Low temperature treatment stops solder creep

-Thermal mismatches between materials are evened out, to prevent the popcorn effect

-High temperature furnace causes solder to melt for a short time, joining the conductive interconnections with the solder

-Low temperature materials are melted into the high temperature solids to form a eutectic philanthropy

-All materials that were not previously reflowed are finally given the opportunity, through a unique plasma process

d) How is wave solder applied to ICs and other components?

-Air waves carry the solder into the crevases between die, helping to fill in the package with rigid dielectric

-Liquid solder touches the underside of the circuit board, with solder adhering to the exposed metal regions to form rigid conductors when cooled

-Liquid solder washes over the circuitry, sealing in the errant transfer molds

-ICs are placed precisely at the spot where the wave curls, for extra powerful flow into the voids

-Laser waves scan the ICs, depositing solder only where the flox hadn't already been burned away

e) How can lids be attached for hermetic seal in IC packages?

-Solder for glass, epoxy for metal-to-metal

-Float the lid on a solder wave, so it will attach properly after the reflowed flux escalates

-Encapsulate fully during transfer mold

-Mortify the lid surface before bifricating the cavity walls

-Epoxy for glass or metal, weld or solder for metal-to-metal

Answer 1

a)-To provide short distance, secure interconnects to another die or a substrate, with very small spacing

b)Tape and Reel spllos can load directly into some of the automated circuit board populating equipment

C)High temperature furnace causes solder to melt for a short time, joining the conductive interconnections with the solder

d)Liquid solder touches the underside of the circuit board, with solder adhering to the exposed metal regions to form rigid conductors when cooled

e)Solder for glass, epoxy for metal-to-metal