Packaging and assembly
Check the basics of semiconductor packages and assembly — wire bonding, flip chip and BGA — with multiple-choice questions.
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Packaging and assembly: key points
A package protects the chip from its environment, connects it electrically to the board and carries away heat. Chips cut from the wafer become products through die bonding, interconnection, encapsulation and other steps.
Chip-to-package connections include wire bonding and flip chip, and package shapes have evolved from types with leads to types like BGA with solder balls on the underside to support higher pin counts.
All Packaging and assembly questions (50)
- Which correctly describes wire bonding?
- Which correctly describes flip-chip mounting?
- Which correctly describes a feature of BGA (ball grid array) packages?
- Which correctly describes dicing?
- Which material is mainly used as the encapsulant in typical resin-molded packages?
- Which materials are commonly used for lead frames?
- Which correctly describes a CSP (chip-scale package)?
- Which correctly describes a feature of wafer-level packaging (WLP)?
- In flip-chip mounting, what is the main purpose of filling the gap between chip and substrate with underfill resin?
- Which composition is widely used as lead-free solder to meet environmental regulations?
- Which correctly describes a feature of QFN (Quad Flat No-lead) packages?
- What is the step called that attaches and fixes the chip at a set position on a lead frame or substrate?
- What is the step called that grinds the back side of a wafer before dicing to thin it and make the package thinner?
- What is the phenomenon called in which, when a moisture-laden resin package is heated in solder reflow, the moisture inside suddenly vaporizes and expands, cracking the package?
- In wire bonding, what is the main reason gold (Au) wire has been increasingly replaced by copper (Cu) wire?
- Which symbol denotes the thermal resistance from the chip junction to the surrounding air, indicating a package's heat-dissipation performance?
- Which method prints solder paste on a printed circuit board, places components and then heats the board in an oven to solder them?
- What is the method called that mounts a memory package stacked on top of a processor package?
- Which long-established package has two rows of pins along both sides and is mounted by inserting them into holes in the board?
- Why does warpage from heating during reflow become a problem for large packages?
- For surface-mount packages, which moisture-related rating specifies, among other things, how long they may be left after opening the moisture-proof packing before reflow?
- In high-power processor packages, what is the metal plate placed on top of the chip to spread heat called?
- Which organic package substrate, used in flip-chip BGAs and similar packages, is made by stacking insulating layers and fine wiring layers?
- Which wire bonding method melts the tip of a gold wire with an electrical discharge to form a ball, then bonds it to the electrode with heat and ultrasonic energy?
- Which package, used in applications needing high reliability such as space, seals its interior with ceramic or metal?
- Which surface-mount package has gull-wing leads coming out of two sides?
- In high-pin-count QFPs, which problem tends to occur if the lead pitch is made too narrow?
- Which method bonds chips to substrates one at a time while heating and applying pressure, and is used to connect thin chips with large warpage and fine-pitch bumps?
- What is the main purpose of adding large amounts of silica filler to mold resin?
- What is the main purpose of placing decoupling capacitors (bypass capacitors) on packages and printed circuit boards?
- Which set correctly describes the main roles of a semiconductor package?
- What is the common step for displaying the part name, lot number and similar on the package surface of a finished IC?
- What is the typical diameter of wires used in wire bonding?
- What is the packing format called in which surface-mount ICs are placed one by one in pockets in a tape and wound up, to be fed to placement machines?
- What is the main advantage of surface mounting compared with inserting leads into holes in the PCB?
- In leadframe packages, what is the main purpose of plating the exposed leads with tin (Sn)-based plating?
- In reflow with lead-free solder (Sn-Ag-Cu), which is closest to the peak temperature that parts experience?
- Which dicing method, with almost no kerf loss, focuses a laser inside the wafer to create a modified layer and then separates chips by stretching the tape?
- Which package has flat electrodes (lands) arranged in a grid on its bottom instead of solder balls?
- What material is most widely used as the base material of printed circuit boards in electronics?
- Why are the molding compounds of many plastic packages black?
- In high-pin-count BGA packages, why are many of the balls assigned to power and ground?
- In wire bonding that forms a ball, where is the first bond (ball bond) generally made?
- What is the main purpose of heating packages in an oven for some time after molding (post-mold cure)?
- What is the defect called in which bonding wires are pushed aside and deformed by the resin flow during molding?
- What change occurs when the temperature of a molding compound exceeds its glass transition temperature (Tg)?
- Which method makes very thin chips by first cutting grooves partway into the wafer from the front and then grinding the back to separate the chips?
- In dense assemblies such as smartphones, what is the purpose of forming a metal film on the package surface by sputtering or similar?
- In reflow, what is the defect called in which one end of a small part such as a chip resistor lifts up so the part stands on end?
- What is the defect called in which the force or ultrasound of wire bonding cracks the insulator or silicon beneath the bond pad?