AI Technology, Inc.

LOW PRESSURE, LOW TEMPERATURE MOLDED ENCAPSULATIONS

With multiple stack chips and proximity of wire-bonding with sub-mil (<25 microns) gold wire and sub-mil spacing, these type of chip scale packaging requires new type of molding compound to form its protections. Traditional epoxy molding compounds requires high pressure and thus high swiping forces on these gold-wire bonding.

The ideal "new generation" of the chip packaging encapsulation includes all of the molding compound characteristics that are part of the material properties of the innovative material design and engineering:

Low pressure molding parameter similar to thermoset molding that is 1/10 or less than traditional epoxy molding compounds
Much less moisture absorption and permeation than traditional molding compound
Coefficient of expansion (CTE) of less than 20 ppm/°C or lower than traditional epoxy molding compound
Higher glass transition temperature (Tg) or softening temperature, and
Much higher modulus than traditional molding compound to provide stable stress reduction due to CTE differences

The following are a list of the "new generation" of low pressure molding compounds and encapsulations from the material scientists from AI Technology, Inc.

LOW PRESSURE MOLDING COMPOUNDS AND ENCAPSULATIONS
AIT Part #	Description	Melt-Flow, Curing, Process Conditions	Modulus (GPa)	CTE (ppm/°C)	Tg (°C)	Dielectric Constant/Loss (1MHz)	Ionic Impurities (Na+, K+, Cl-, etc.)
MC9883-LPM	Quartz filled Semi-solid mixture Ultra low CTE	Injection or transfer @40-60°C Curing @ 175°C/10 sec	8.0	16	236	3.8/0.01	< 10 ppm

MC9885-LPM	Alumina filled Semi-solid mixture Thermally conductive	Injection or transfer @40-60°C Curing @ 175°C/10 sec	8.0	18	236	4.2/0.01	< 10 ppm

Application Notes: Low pressure molding compounds and encapsulations are designed to have strong adhesion to most substrates used in electronic applications. All molding surfaces in contact with the curing encapsulations and molding compounds must be coated with release coating such as PTFE or silicone for releasing for multiple uses. Low pressure molding compounds and encapsulations are premixed, deaerated (degassed) and ready for molding without further mixing. Transfer of the molding compounds and encapsulations is to performed at temperature below 60°C to ensure long processing time without curing at the transferring chambers.

High Temperature Underfills

For the traditional flip-chip underfilling, anhydride based epoxy encapsulation have been successful at least to meet the the JEDEC/IPC level 3 of moisture sensitivity. To meet the more stringent level 1 or 2 moisture sensitivity, the underfills must absorb much less moisture to reduce the potential moisture-induced failure.

More stringent stress management and reduction of moisture sensitivity are more important in the stack chip applications such as "through silicon vias" (TSV) interconnected stack chip packages.

AI Technology material scientists have developed a series of new generation underfills that withstand RoHS compliant higher temperature processing and applications. The main advanced features and functions are listed below alone with the table of characteristics:

Much lower moisture absorption and sensitivity than traditional epoxy underfills
Lower and faster curing at relatively low temperatures of 150°C
Higher Tg and modulus to enhance stress reduction
Lower ionic impurities for even higher device reliability

HIGH TEMPERATURE UNDERFILLS
AIT Part #	Description	Capillary-Flow, Curing, Process Conditions	Modulus (GPa)	CTE (ppm/°C)	Tg (°C)	Dielectric Constant/Loss (1MHz)	Ionic Impurities (Na+, K+, Cl-, etc.)
MC7883-UF	Quartz filled Liquidous mixture Ultra low CTE	Capillary flow @40-80°C Curing @ 150°C/90 sec	7.5	19	236	3.8/0.01	< 10 ppm

MC7885-UF	Alumina filled Liquidous mixture Thermally conductive	Capillary flow @40-80°C Curing @ 150°C/90 sec	7.5	20	236	4.2/0.01	< 10 ppm

Application Notes: High temperature underfill is to be dispensed onto two adjacent sides of the chip to be underfill. Enhanced capillary flow action with temperatures of 40-60°C following with curing at temperatures of 150-200°C.

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LOW PRESSURE MOLDING COMPOUNDS AND ENCAPSULATIONS

HIGH TEMPERATURE UNDERFILLS