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DMI-3006 Negative Type Solvent Developed Photosensitive Modified Polyimide Stress Buffer Coating

Harmonization Code : 3707.90.90.00 | Chemical preparations for photographic uses (other than varnishes, glues, adhesives and similar preparations); unmixed products for photographic uses, put up in measured portions or put up for retail sale in a form ready for use : Other : Other

Main features

No warpage of silicone wafer
UV cured, no hard bake required
Excellent dielectric properties

Product Description

DMI’s stress buffer coating is a negative type, solvent developed, photosensitive polyimide based precursor for stress buffer applications.

DMI’s photosensitive polyimide coating uses a modified polymide which outperforms industry standards because of its very low cure temperature and very low modulus. These two qualities ensure that there is minimum wafer warpage of the silicon wafer.

DMI’s photosensitive polyimide coating also guarantees excellent cured film properties such as great electrical performance because of its high dielectric strength and constant. The coating has a very low moisture absorption and high elongation giving it its high reliability.

DMI's photosensitive polyimide coating's main application is as a stress buffer or wafer buffer layer in wafer level packaging (WLP). The coating's low cure temperature and high dielectric strength ensure excellent performance as stress buffer in wafer level packaging. Other applications include post passivation layers for solder bumping or dielectric layer in wafer level packages.

Technical Specifications

Chemical Properties

Moisture Absorption

Moisture Absorption
Moisture absorption shows the capacity of a polymer to absorb moisture from its environment.

Absorbed moisture can reduce the glass transition temperature and strength of a polymer and can also result in popcorning, unreliable adhesion or voids in the bond line due to moisture desorption or entrapment.

Moisture absorption should always be mentioned with the test conditions to provide a meaningful frame of reference.

Moisture Absorption - 24h @ 23°C | 50%RH

0.1 %

Water Absorption @ 23°C/24h

0.1 %

Mechanical Properties

Elongation

Elongation
Elongation is the process of lengthening something.

It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks.

It is commonly referred to as Ultimate Elongation or Tensile Elongation at break.

62 %

Storage (DMA) Modulus
Storage (DMA) Modulus @ 25°C	100 N/mm2

Tensile Strength

Tensile Strength
The tensile strength of a material is the maximum amount of tensile stress that it can withstand while being stretched or pulled before failure.

Some materials break very sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation and possibly necking before fracture.

Tensile Strength

Tensile Strength
Tensile strength determines the resistance of a material to break under tension and it measures how much elongating load (or tensile stress) it can handle before fracture.

To make it simple, it measures how much force we have to apply when pulling apart a material before it breaks.

8.1358 MPa

Electrical Properties

Dielectric Constant

Dielectric Constant
Dielectric Constant (k), commonly known as relative permittivity, is a number relating the ability of a material to carry alternating current to the ability of vacuum to carry alternating current.

It determines the ability of an insulator to store electrical energy and is the ratio of electric permeability in vacuum against the electric permeability of a material.

The lower the dielectric constant (κ) and dissipation factor, the less energy is absorbed from an electric field, making it a much better insulator.

It is a dimensionless property that can be affected by various factors such as the thickness uniformity of a material, insufficient contact between the sample and electrodes, water adsorption and contact resistance.

Dielectric Constant (IPC-TM-650 2.5.5.9) 1.5 GHz

2.6

Dissipation Factor

Dissipation Factor
Dissipation factor is commonly known as loss tangent or tan delta.  

It is a ratio of the loss index and the relative permittivity and it measures the inefficiency of an insulating material to maintain energy (that otherwise dissipates in the form of heat). The lower the factor, the better the insulation.

It is the reciprocal of the quality factor and always refers to a specific temperature and frequency.

Dissipation Factor (IPC-TM-650 2.5.5.9) 1.5 GHz

0.001

Thermal Properties

Weight Loss
5% Weight Loss Temperature	358 °C

Coefficient of Thermal Expansion (CTE) Coefficient of Thermal Expansion (CTE) CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material. Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE), α1 Coefficient of Thermal Expansion (CTE), α1 CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg). It explains how much a material will expand until it reaches Tg.	164 ppm/°C
Coefficient of Thermal Expansion (CTE), α2 Coefficient of Thermal Expansion (CTE), α2 CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg). It explains the extent to which a material will expand after it passes Tg.	222 ppm/°C

Decomposition Temperature

446 °C

Glass Transition Temperature (Tg)

Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.

54 °C

Additional Information

We would like to pattern the DMI-3006. Do we need the R1247 developer or can we use a mixture of conventional solvents?

We can supply the material but we would prefer if you prepared your own supply for two reasons:

You likely have these solvents in your inventory
Shipping flammable solvents is very expensive

The R1247 is a simple mixture of 85 wt. % cyclopentanone (a common solvent used for developing) and 15 wt. % ethanol. We just add the two solvents to a container and shake to blend them together. We have found that pure cyclopentanone is a little too aggressive to the DMI-3006 so blending with ethanol reduces its nature.