Key indicators before and after sintering of LTCC raw porcelain tapes

Key indicators before and after sintering of LTCC raw porcelain tapes
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LTCC was prepared by flow casting method, the basic properties before sintering are its inherent mechanical properties, and the basic properties after sintering are its mechanical, electrical and thermal properties related to its application. the basic properties of LTCC ceramic raw ribbons can be divided into pre-sintering properties and post-sintering properties according to its material state.
1, the main performance indicators before sintering
LTCC ceramic belt sintering before the main performance indicators are.
1) surface quality: texture uniformity, surface flatness, color consistency, etc.
2) Surface roughness: the surface finish of the raw ceramic tape, commonly known as surface finish, refers to the small spacing and micro-peak and valley unevenness of the raw ceramic tape surface, the unit is μm
3) Thickness: the thickness of the raw porcelain tape porcelain body without polyester support film.
4) Width: green ceramic tape film width in the middle of the thickness of uniform, remove a few millimeters after the tape edge.
5) Peel strength: the force required to remove the green ceramic tape film per unit width from the polyester support film at a certain angle and rate, unit: n/cm or GF/cm.
7) Young's modulus (E): also known as the modulus of elasticity, is the strain (ε) and stress (σ) along the length or width of the unprocessed ceramic tape film, proportional to the stress-strain ratio within the elastic limit (E = σ/ε), in pa (n/m2).
(8) dimensional stability: the flatness of raw porcelain without film after drying pretreatment, the rate of change in size after drying pretreatment in the workshop environment for long-term storage, the rate of change in size of raw porcelain before and after lamination.
2, the main performance indicators after sintering
The main performance indicators of LTCC green ceramic tape after sintering include.
1) sintering shrinkage: LTCC substrate sintering shrinkage rate η, refers to the linear size reduction of LTCC substrate after sintering relative to the percentage of the size before sintering, can be divided into X direction (length) shrinkage rate η10. Y direction shrinkage rate (width) ηY and Z direction shrinkage rate (thickness) ηZ
2) Surface quality: Texture uniformity, surface flatness, color consistency, etc. of LTCC substrates.
3) Surface roughness: The surface finish of LTCC substrate can still be characterized by the arithmetic mean deviation Ra of the profile or the maximum height RZ of the profile.
4) Warpage: also known as unevenness, is the maximum unevenness dimension of the LTCC substrate in the thickness direction divided by the maximum plane dimension (diagonal length), in μm/mm
5) Density: LTCC substrate mass per unit volume (weight), that is, the ratio of weight to volume, the unit is g/cm3.
6) Bending strength: also known as bending strength and flexural strength. bending strength of LTCC substrate is the maximum stress (maximum pressure) per unit cross-sectional area that can be withstood before the LTCC substrate fractures.
7) Young's modulus (E): also known as elastic modulus, is the strain (ε) and stress (σ) along the length or width of a sintered LTCC substrate, proportional to the stress-strain ratio within the elastic limit (E=σ/ε) in pa (n/m2). However, the brittleness of ceramic and glass materials for LTCC substrates is characterized by no or only small plastic deformation and by cracks or fractures.
8) Dielectric constant: Dielectric constant ε it is a quantitative measure of the ease with which a dielectric material can be polarized to form a dipole capable of counteracting an applied electric field (voltage), and a measure of the ability of a dielectric to store energy, ε = εoεr. The unit is f/m.
(9) dielectric loss: also known as loss factor and loss angle tangent, refers to the action of the AC electric field, due to the dielectric conductivity and dielectric polarization of the hysteresis effect, so that the insulation material internal heating and energy loss.
10) Volume resistivity: The volume resistivity ρ of LTCC material after sintering is equal to the insulation resistance R of the LTCC substrate sample in the thickness direction multiplied by the ratio of substrate (electrode) area a to thickness T, ρ = RA/T, unit is Ω-cm.
(11) Thermal conductivity: also known as thermal conductivity, is the area heat flow of LTCC substrate in the process of thermal conductivity divided by the temperature gradient, the unit is w/(m-K).
12) Thermal expansion coefficient: the ratio of the increase in length of LTCC substrate to the original length (relative change in length) caused by a unit temperature change under constant pressure (constant pressure), in PPM/°C (10-6/°C).
LTCC green ceramic tape is the most essential functional material and component in LTCC substrate manufacturing. It is the key to LTCC technology. Its performance directly affects the process behind LTCC technology and the performance of components based on LTCC technology.
Essentially, the performance of the LTCC substrate depends on the properties of the LTCC raw ceramic strip used. The performance specifications of the raw ceramic strip after sintering essentially represent the target performance specifications that can be achieved by the LTCC substrate. Therefore, after the raw ceramic tapes are prepared, manufacturers usually perform rigorous testing before proceeding to the next process in order to detect defects in a timely manner.
Article source: Zhongwei He, Xiaowei Wang, Ran Li, Liang Gao, "Study on the basic performance testing method of LTCC raw ceramic tapes