Different IC Package types

[Freshman]

What factors determine the package type of an integrated circuit (IC)?

I’ve noticed that different components come in various package types such as SOIC, DIP, DFN, and QFN. What are the key considerations that dictate which package is used for a given IC?

[jpanhalt]

Market.

[squadchannel]

Board space, mechanically space, hand soldering or reflow soldering, availability, price, ease of routing, whether the footprint fits the PCB fab's manufacturing capabilities, etc.

[Freshman]

My question was like, why do manufacturers, or how do manufacturers decide what a certain device package should be?

Suppose, let's take LDOs or switching regulator products. A manufacturer makes a lot of them. Some of the Regulators are QFN, while some are DFN, while some are QFP?

What factors are being considered by the manufacturer that enables to finalize that a particular package would be right?

[AnalogTodd]

Market is the major driver. However, there are a number of other factors that will weigh in on how a manufacturer packages a part.

• Die size: the die must be able to fit in the package with appropriate clearances.
• Number of pins and pad locations on die: part controls/interfacing need to come out to separate pins. There needs to be enough room on the die to place all these pins with clearances from one bond to another. Sometimes it is smaller to use four sides for pins instead of two.
• Thermal characteristics: depending on the type of part, a good thermal path is needed to dissipate power. For example, an LDO dissipates power equal to roughly (Vin - Vout) * Iload. That power creates heat that must be dissipated to avoid operational issues.
• Current handling: bond wires from die to package pins cannot carry too much current before becoming a fuse. Often multiple bond wires are needed to carry full current for a part, and only a certain number of bond wires can be attached to a pin.
• Product performance: there are a lot of parts out now where overall performance is improved with appropriate packaging. Some switching regulators use two switches that run their current loops in opposing directions to lower EMI.
• Solderability and inspection capability: some customers want to be able to do visual inspections of solder joints, others are OK with occasional X-ray. Leaded parts allow for visual inspection of solder joints, QFN and DFN do not.

Overall, a big driver is getting things into smaller size overall. It is nice to have a cell phone with as much capability as it has in your pocket as opposed to the huge items that the same thing would have taken 25 years ago.