| Liquid
Epoxy Electronic Packaging Materials
------Two series of liquid Epoxy
electronic packaging materials available: 1) Electrically/Thermally
Conductive Adhesives, and 2) Liquid Epoxy Underfill and Encapsulants.
The main applications include the die attach (Figure 1), Flex
interconnects (Figure 2), chip-bonding (Figure 3), underfilling
and encapsulating FC-BGA/CSP devices.

Liquid Epoxy Materials for Microelectronic Packaging
Applications
Electrically/Thermally Conductive Adhesives
------ZKEP series electrically conductive
adhesives (ECA), prepared by mixing of high purity, low viscous,
high adhesive epoxy resins with silver plates, and curing agent,
catalyst and surfactants, are single component without evolving
of organic volatile in thermal curing process, which could be
directly used with addition of any other components prior to use.
------ZKEP series thermally conductive
adhesives (TCA),prepared by mixing of high purity, low viscous,
high adhesive epoxy resins with high thermal conductive powders
such as Si3N4,
Al2N3, and
curing agent, catalyst and surfactants, are single component without
evolving of organic volatile in thermal curing process, which
could be directly used with addition of any other components prior
to use.
------Three issues, i.e the physical
properties, application methods and cure conditions of the adhesives
should be taken into account before choosing the optimal electrically
conductive adhesives or thermally adhesives, because the adhesive
features have a big impact on your product performance. It is
recommended that the customer should perform a through evaluation
for any application based on their specific requirements.
Advantageous Features:
1. Single Components, ,easy processing and handling
2. High purity, low impurity
3. High electrically or thermally conductivity
4. Good adhesion to substrates such as Si, GaAS,
SiO2, Si2N3,
Cu, Al, Ni
5. Good storage stability
Typical Applications
1. Die attach in hybrid microelectronics, semiconductor packaging
and assembly
2. Quartz crystal attach
3. LED attach and interconnetc
4. Flip chip underfill for FC-BGA, FC/CSP,
5. Solder replacement
6. High temp Solder replacement
7. Chip bonding such as chip on leadframe, chip on board, flip
chip,
8. Flexible interconnetion in fiber optics, optoelectronics,
medical devices, solder replacement
Table 1 ZKEP Series Electrically/Thermally Conductive Adhesives
| Products |
ZKEP4010 |
ZKEP4020 |
ZKEP4030 |
ZKEP4040 |
| Components |
Single |
| Appearance |
Silver Liquid |
Silver Liquid |
Silver Liquid |
Gray Liquid |
| AbsoluteViscosity(mPa·s) |
3000 |
2700 |
3600 |
5200 |
| Filler (wt %) |
65-72 (Silver) |
65-72 (Silver) |
65-72 (Silver) |
65-72 (AI2O3) |
| Thixotropic Index |
3-5 |
3-5 |
3-5 |
3-5 |
| Storage Stability |
>6months
(-20 ℃) |
>6months
(-20 ℃) |
>6months
(-20 ℃) |
>6months
(-20 ℃) |
| Curing Condition |
150 ℃/1hr |
150 ℃/1hr |
150 ℃/1hr |
150 ℃/1hr |
| Pot life |
48 hrs |
48 hrs |
48 hrs |
48 hrs |
| Impurity(pp) |
Na+ |
<0.1 |
<0.1 |
<0.1 |
<0.1 |
| K- |
<5 |
<5 |
<5 |
<5 |
| Cl- |
<0.2 |
<0.2 |
<0.2 |
<0.2 |
| Tg (℃) |
90℃ |
110℃ |
115℃ |
86℃ |
| Moisture Uptakes(%) |
0.68 |
0.56 |
0.84 |
0.50 |
| Modulus(GPa) |
1.4 |
1.6 |
1.4 |
1.8 |
| CTE(ppm/℃)
|
45.2 |
33.9 |
36.5 |
54.1 |
| Thermal Conduc.(W/m·℃) |
3.2 |
3.3 |
3.2 |
3.3 |
| Elec. Conductivity(×10-4Ω·cm) |
1-3 |
5-7 |
1-3 |
1-3 |
| Shear Strength(MPa) |
≥5.0 |
≥5.0 |
≥5.0 |
≥5.0 |
Liquid Epoxy Electronic Packaging Materials
------ZKEP series liquid epoxy electronic
packaging materials (LEEP), including FC-BGA/CSP underfill and
over encapsulants, prepared by mixing of high purity, low viscous,
high adhesive epoxy resins with spherical silica filler, and curing
agent, catalyst and surfactants, are single component without
evolving of organic volatile in thermal curing process, which
could be directly used with addition of any other components prior
to use.
------FC-BGA/CSP underfill are
highly flowable, high purity, one component liquid, suitable for
the gap size and solder bump pitch > 25 µm. After thermally
cured, a uniform and void free underfill layer under flipchi devices
was formed for protecting the active surface of the die while
improving the device reliability by distributing stress away from
the solder interconnects.
------Several issues should be taken
into account before selecting the optimal underfill and encapsulants,
because the adhesive features have a big impact on your product
performance. The physical properties, such as viscosity, thixotropic
index, and working life, and the curing condition will usually
influence on the processing of applying the liquid. Glass transition
temperature, shear strength and modulus of the cured materials
will affect the product performance. It is recommended that the
customer should perform a through evaluation for any application
based on their specific requirements.
Advantageous Features:
1. Single Components, easy processing and handling
2. High purity, low impurity
3. low stress, low CTE
4. Good adhesion to substrates such as Si, GaAS,
SiO2, Si2N3,
Cu, Al, Ni
5. Good storage stability
Typical Applications
1. Flip chip underfill for FC-BGA, FC/CSP
2. Device Encapsulantion
3. Die attach in hybrid microelectronics, semiconductor packaging
and assembly
4. Quartz crystal attach
5. LED attach and interconnetc
Table 2 ZKEP Series Liquid Epoxy Underfills
| Products |
ZKEP4110 |
ZKEP4120 |
ZKEP4130 |
ZKEP4140 |
| Components |
Single |
| Appearance |
Viscous Liquid |
Viscous Liquid |
Viscous Liquid |
Viscous Liquid |
| Absolute Visicosity(Pa·s) |
12-14 |
14-16 |
6-8 |
12-14 |
| Filler(wt.%) |
65-72 (Silver) |
65-72 (Silver) |
65-72 (Silver) |
65-72 (AI2O3) |
| Part Gap/PitchSize Filled |
>25μm |
>25μm |
>25μm |
>25μm |
| Storage Stability |
>6 months
(-40℃) |
>6 months
(-40℃) |
>6 months
(-40℃) |
>6 months
(-40℃) |
| Impurity(ppm) |
Na+ |
<3 |
<3 |
<3 |
<3 |
| K- |
<5 |
<5 |
<5 |
<5 |
| Cl- |
<6 |
<6 |
<6 |
<8 |
| Tg ( ℃) |
100 ℃ |
120℃ |
145℃ |
110℃ |
| Moisture Uptakes(%) |
< 0.7 |
<0.6 |
<0.8 |
<0.8 |
| Modulus(GPa) |
1.5 |
1.6 |
1.4 |
1.8 |
| CTE(ppm/℃)
|
25 |
24 |
27 |
28 |
| Adhesion Strength(MPa) |
≥3.0 |
≥3.0 |
≥3.0 |
≥3.0 |
Note:
- ------ZKEP4110 series are high
flowable, high purity, one component underfill. A uniform and
void free underfill layer could be formed under flip chip devices,
protecting the active surface of the die while improving reliability
by distributing stress away from the solder interconnects.
- ------ZKEP4120 series are low
stress underfill formulated for rapidly flowing under 25 µm
gap and for ceremic or laminate substrates where minimal stress
is important.
- ------ZKEP4130series are low
alpha particle emission underfill formulated for rapidly flowing
under 25 µm gap and for low stress and low modulus applications.
- ------ZKEP4140 are low alpha
particle emission underfill formulated for rapidly flowing under
25 µm gap and for high Tg and low CTE applications.
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