Lanthanum borate calcium glass / alumina ceramic composite ltcc microwave dielectric material and performance adjustment method

Abstract

The application relates to the technical field of ceramic materials, in particular to a lanthanum-boron-calcium glass / alumina ceramic composite LTCC microwave dielectric material and a performance adjusting method, which comprises, by mass percentage, 30-50% of lanthanum-boron-calcium glass A powder, 0-20% of lanthanum-boron-calcium glass B powder and 48-52% of alumina powder; the particle size of the lanthanum-boron-calcium glass A powder is 1-3 mu m, and the particle size of the lanthanum-boron-calcium glass B powder is 0.5-2 mu m; the lanthanum-boron-calcium glass A powder comprises La2O3, B2O3, CaO, P2O5, SiO2, alkali metal oxide and ZrO2; and the lanthanum-boron-calcium glass B powder comprises La2O3, B2O3 and CaO. The application adjusts the performance of the LTCC microwave dielectric material by adjusting the relative content of the lanthanum-boron-calcium glass A and B, improves the sintering performance of the LTCC green ceramic material, enhances the adaptability of the LTCC green ceramic material to the conductor material, and optimizes the mechanical and dielectric performances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic ceramics and its manufacturing technology, and particularly relates to a lanthanum-boron-calcium glass / alumina ceramic composite LTCC microwave dielectric material and a performance adjusting method. BACKGROUND

[0002] Low temperature co-fired ceramic (LTCC) plays an increasingly important role in the field of high integration and high reliability electronic packaging. LTCC is a new packaging technology in which a conductor metal (gold-silver-copper) with high electrical conductivity and low melting point is used as electrode material and is co-sintered with a multi-layered LTCC green ceramic material at a temperature lower than 900 DEG C to form an electronic functional module. The green ceramic material is sintered into a substrate material, which has good dielectric properties and mechanical properties and can provide effective support and protection for the internal three-dimensional circuit.

[0003] Currently, there are three types of substrate materials: microcrystalline glass system, glass / ceramic composite system and ceramic system. The LTCC green ceramic of the glass / ceramic composite system is obtained by mixing glass powder and ceramic powder with a certain proportion. In the system, the glass is a low-melting-point glass, which melts during the sintering process, infiltrates the ceramic particles, and the ceramic particles are rearranged under the action of internal stress, and the whole material is densified and shrunk, and an isotropic substrate material is obtained after cooling. Lanthanum-boron-calcium glass is a LTCC substrate material system with great application potential. During the sintering process, CaB2O4 and LaBO3 crystal phases with excellent dielectric properties can be precipitated. If P2O5 is introduced into the lanthanum-boron-calcium glass, LaPO4 crystal phase with excellent dielectric properties can be precipitated. When co-sintered with Al2O3, part of the Al2O3 can be dissolved, and CaAl2B2O7 crystal phase with good mechanical and dielectric properties can be precipitated at the interface. Due to the use of gold-silver-copper as the conductor material, the wire width can be reduced to 50 μm, so more wires and passive devices can be arranged in the same space, and the integration and performance of the LTCC device can be improved.

[0004] However, the LTCC microwave dielectric material still has the following problems: 1) during the sintering preparation process, the conductor material and the substrate material are not synchronized in shrinkage, which causes adhesion defects between the conductor material and the substrate material, resulting in deformation or disconnection of the circuit and causing the device to fail; 2) during the sintering of the substrate, the internal stress is not uniform, causing the substrate to deform and warp; 3) due to the difference in thermal expansion coefficient between the substrate material and the surface mounted components, the packaging shell and other components of the LTCC device, the deformation is not synchronized under thermal shock, causing stress, resulting in problems such as cracking of the sealing part and falling off of the device. The sintering properties and thermal expansion coefficient of the substrate material can be adjusted to solve the above problems.

[0005] Therefore, it is necessary to provide an improved lanthanum-boron-calcium glass / alumina ceramic composite LTCC microwave dielectric material and a performance adjusting method to solve the above problems. SUMMARY

[0006] The present application aims to provide a lanthanum borocalcium glass / alumina ceramic composite LTCC microwave dielectric material and a performance adjustment method.

[0007] To achieve the above-mentioned purpose, in a first aspect, the present application provides a LTCC microwave dielectric material, comprising, by mass percentage: lanthanum borocalcium glass A powder 30% to 50%, lanthanum borocalcium glass B powder 0% to 20% (not including the boundary value 0%), and alumina powder 48 to 52%.

[0008] The particle size of the lanthanum borocalcium glass A powder is 1 to 3 microns, and the particle size of the lanthanum borocalcium glass B powder is 0.5 to 2 microns.

[0009] The composition of the lanthanum borocalcium glass A powder includes La2O3, B2O3, CaO, P2O5, SiO2, alkali metal oxide and ZrO2; and the composition of the lanthanum borocalcium glass B powder includes La2O3, B2O3 and CaO.

[0010] The lanthanum borocalcium glass system is a kind of low melting point, easy to crystallize glass system, which will soften and infiltrate Al2O3 particles to complete the densification sintering in sintering, and precipitate a variety of dielectric and mechanical performance good crystal phase. Al2O3 is uniformly dispersed in the glass matrix, which plays a dispersion strengthening role, and it itself has good high-frequency dielectric properties. In addition to La2O3, B2O3 and CaO, P2O5, SiO2, ZrO2 and alkali metal oxide are added to the lanthanum borocalcium glass A powder. The lanthanum borocalcium glass B powder only contains La2O3, B2O3 and CaO. The difference between the two glass powder compositions is used to control the crystal structure during sintering.

[0011] The present application adjusts the relative content of the above-mentioned lanthanum borocalcium glass A and B powder to adjust the performance of the LTCC microwave dielectric material, so as to improve the co-firing adaptability of the LTCC microwave dielectric material and the conductor material. Especially, it can adjust the shrinkage and thermal expansion coefficient and other properties while ensuring the tensile strength to be above 2.20 kg, so the comprehensive performance is excellent. The problem of warping, delamination of the substrate material and the decrease of the adhesion of metal wiring after sintering caused by the mismatch of the sintering characteristics of the substrate material and the slurry during the co-sintering of the LTCC device is solved, the finished product quality and yield of the LTCC material are improved, and it can be widely used in the field of high-frequency dielectric packaging.

[0012] Further, the components of the lanthanum borocalcium glass A powder include, by mass percentage, La2O3 30-40%, B2O3 35-50%, CaO 15-25%, P2O5 0-10%, SiO2 0-10%, alkali metal oxide 1-5%, and ZrO2 1-3%.

[0013] Further, the components of the lanthanum borocalcium glass B powder include, by mass percentage, La2O3 37-47%, B2O3 30-40%, and CaO 13-23%.

[0014] Further, the components of the lanthanum borocalcium glass A powder include, by mass percentage, La2O3 30-40%, B2O3 35-50%, CaO 15-25%, P2O5 0-10%, SiO2 0-10%, alkali metal oxide 1-5%, and ZrO2 1-3%.

[0015] Further, the components of the lanthanum borocalcium glass B powder include, by mass percentage, La2O3 37-47%, B2O3 30-40%, and CaO 13-23%.

[0016] In some embodiments, the median particle size of the lanthanum borocalcium glass A powder is 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 3 μm, etc., and the median particle size of the lanthanum borocalcium glass B powder is 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, etc. The median particle size of the lanthanum borocalcium glass A powder is greater than the median particle size of the lanthanum borocalcium glass B powder.

[0017] A particle size that is too large results in a weakened tendency of crystallization during the sintering process, and the inter-particle voids increase, thereby reducing the bulk density and affecting the sintering quality. A particle size that is too small results in a too strong tendency of crystallization, and increases the manufacturing cost.

[0018] Compared with the lanthanum borocalcium glass A powder, the relative content of the network external oxide La2O3 in the lanthanum borocalcium glass B powder is high, the relative content of the glass forming oxide B2O3 is low, the glass has a stronger tendency of crystallization, and can quickly crystallize at a lower sintering temperature during the sintering temperature rising process. Moreover, the particle size of the lanthanum borocalcium glass B powder is smaller than that of the lanthanum borocalcium glass A powder, the surface energy is greater, and the surface defects are more, so the lanthanum borocalcium glass B powder is more easily softened and strongly crystallized during sintering, and quickly crystallizes a large amount of crystal phases. After sintering at 700°C, the lanthanum borocalcium glass A powder is still in an amorphous glass phase, while the lanthanum borocalcium glass B powder has obvious crystallization of crystal phases.

[0019] A small amount of the lanthanum borocalcium glass B is used to replace the lanthanum borocalcium glass A powder in the LTCC green ceramic. For example, Figure 3, before 750℃, lanthanum boron calcium glass A powder begins to soften and infiltrate Al2O3, the substrate material is densified and shrinks, at this time, lanthanum boron calcium glass B is strongly crystallized, which hinders the shrinkage of the material to a certain extent. At 750℃-850℃, lanthanum boron calcium glass A is strongly crystallized, the glass phase stops shrinking and expands to a small extent. After adjustment, the sintering rule of the LTCC green ceramic and the conductor material is more matched, lanthanum boron calcium glass B is strongly crystallized in advance, so that the green ceramic is not easy to deform in the shrinkage stage before 750℃, and more LaBO3 crystal phase with excellent high-frequency dielectric properties can be crystallized. At the same time, the phase composition of the substrate material changes after sintering, and the thermal expansion coefficient also changes, which is more suitable for the application environment.

[0020] Further, the preparation method of the lanthanum boron calcium glass A powder comprises: taking La2O3, H3BO3, CaCO3, Ca3(PO4)2, SiO2, Na2CO3, Li2CO3, and ZrO2 as raw materials, and uniformly mixing the raw materials in a three-position mixer according to the proportion. Each raw material needs to be dried in advance, and the purity of the raw material and the volatilization amount of part of the oxides in the melting process need to be considered when the raw material is weighed. After sufficient mixing, the raw materials are loaded into a platinum crucible and placed into a high-temperature furnace to complete the melting at 1300-1500℃ for 2±0.5h. The glass liquid is poured into a double-roller cooling mill to complete quenching and obtain lanthanum boron calcium glass A glass sheet. The glass sheet is preliminarily broken and screened through a 50-mesh sieve to remove larger particle fragments. The broken glass is poured into a ball mill tank, alumina ceramic balls are added as grinding media, and the lanthanum boron calcium glass A powder is ground into a powder with a particle size of 1-3μm to obtain the lanthanum boron calcium glass A powder.

[0021] The preparation method of the lanthanum boron calcium glass B powder comprises: taking La2O3, H3BO3, and CaCO3 as raw materials, and uniformly mixing the raw materials in a three-position mixer according to the proportion. Each raw material needs to be dried in advance, and the purity of the raw material and the volatilization amount of part of the oxides in the melting process need to be considered when the raw material is weighed. After sufficient mixing, the raw materials are loaded into a platinum crucible and placed into a high-temperature furnace to complete the melting at 1300-1500℃ for 2±0.5h. The glass liquid is poured into a double-roller cooling mill to complete quenching and obtain lanthanum boron calcium glass B glass sheet. The glass sheet is preliminarily broken and screened through an 80-mesh sieve to remove larger particle fragments. The broken glass is poured into a ball mill tank, alumina ceramic balls are added as grinding media, and the lanthanum boron calcium glass B powder is ground into a powder with a particle size of 0.5-2μm to obtain the lanthanum boron calcium glass B powder.

[0022] Further, the LTCC microwave dielectric material comprises, by mass percentage, 34%-46% of the lanthanum boron calcium glass A powder, 4%-16% of the lanthanum boron calcium glass B powder, and 50% of the alumina powder.

[0023] Further, the alumina powder is α-Al2O3, and the particle size is 2-3 μm, preferably, the desired ceramic powder particle size is sieved out using an air flow classifier.

[0024] In a second aspect, the present application provides a LTCC green ceramic tape, which is prepared by using the LTCC microwave dielectric material of any one of the above as the main raw material.

[0025] In a third aspect, the present application provides a preparation method of a LTCC green ceramic tape, which comprises the following steps: uniformly mixing lanthanum borocalcium glass A powder, lanthanum borocalcium glass B powder, alumina powder, and an organic binder, a solvent, and a plasticizer to obtain casting slurry, and casting the casting slurry after defoaming treatment to obtain the LTCC green ceramic tape.

[0026] In some embodiments, the Al2O3 ceramic powder particles with a particle size of 2-3 μm are sieved out using an air flow classifier. The glass powder and the ceramic powder are added into a ball mill tank in a proportion of 30-50% of lanthanum borocalcium glass A powder, 0-20% of lanthanum borocalcium glass B powder, and 50% of alumina ceramic, and multiple kinds of alcohol, butanone, cyclohexanone, and terpineol are added as solvents, acrylic resin and ethyl cellulose are added as binders, butyl phthalate is added as a plasticizer, and alumina ceramic balls are added as grinding media, and the mixture is mixed for 24 h using a roll mill to prepare uniform casting slurry. After defoaming of the slurry, a casting machine is used to cast the green ceramic tape with a thickness of 100-150 μm, and a cutting machine is used to cut the green ceramic tape into green ceramic pieces.

[0027] The thickness of the LTCC green ceramic tape is 100-150 μm, and the solid content is >90%;

[0028] Further, the solvent comprises at least two of alcohol, butanone, cyclohexanone, and terpineol; the organic binder comprises at least one of acrylic resin and ethyl cellulose; and the plasticizer comprises at least one of dibutyl phthalate and dioctyl phthalate.

[0029] In a fourth aspect, the present application provides a LTCC substrate material, which is obtained by cutting, demolding, and hot pressing the above green ceramic tape and then sintering.

[0030] Further, the dielectric loss of the LTCC substrate material is less than 1×10 -3 ; the shrinkage rate in the X / Y direction is less than 8.5%; the thermal expansion coefficient is less than 6 ppm / ℃; and the tensile strength is greater than 2.20 kg.

[0031] Further, the present application provides a preparation method of the LTCC microwave dielectric material, which comprises the following steps:

[0032] (1) Glass raw material preparation: the raw materials are prepared according to the required proportion of two glass components.

[0033] (2) Glass raw material mixing: raw materials are prepared according to the component proportion requirement, and a three-dimensional mixer is used to mix the raw materials thoroughly.

[0034] (3) Glass melting: the glass raw materials are loaded into a platinum crucible to melt the glass, the melting temperature is 1300-1500 DEG C, and the melting time is 2h.

[0035] (4) Glass forming: after the glass melting is finished, the glass liquid is poured into a double-roller cooling mill to roll and quench to form.

[0036] (5) Glass powder grinding: after the glass is preliminarily broken, the lanthanum borocalcium glass A is sieved through a 50-mesh sieve, the lanthanum borocalcium glass B is sieved through an 80-mesh sieve, the glass fragments with too large volume are sieved out, the lanthanum borocalcium glass A is ground into a powder in the range of 1-3 microns by using a ball milling method, and the lanthanum borocalcium glass B is ground into a powder in the range of 0.5-2 microns.

[0037] (6) Al2O3 ceramic particle screening: an air flow classifier is used to screen the Al2O3 ceramic powder with a particle size of 2-3 microns.

[0038] (7) Casting slurry preparation: the lanthanum borocalcium glass powder and the Al2O3 ceramic powder are added into a ball mill tank according to the proportion, an organic binder and a solvent are added, alumina ceramic balls are used as the mixing medium, and a roll mill is used to mix for 24h to prepare a uniform casting slurry.

[0039] (8) Casting forming: after the slurry is degassed, a casting machine is used to cast a green ceramic strip with a thickness in the range of 100-150 microns, and a cutting machine is used to cut the green ceramic strip.

[0040] (9) Sintering: after the prepared green ceramic strip is cut, demolded and hot-pressed, it is sintered at 800-900 DEG C for 10-40 min to obtain an LTCC substrate material. Alternatively, after the green ceramic strip is cut, a circuit is printed and then sintered to obtain an LTCC device.

[0041] The application also provides a performance adjustment method of an LTCC microwave dielectric material. According to the performance of a conductor material to be matched, the proportion of lanthanum borocalcium glass A powder and lanthanum borocalcium glass B powder in the LTCC green ceramic is adjusted, wherein the lanthanum borocalcium glass A powder accounts for 30-50% of the total mass of inorganic powder, and the lanthanum borocalcium glass B powder accounts for 0-20% of the total mass of inorganic powder. The matching of the green ceramic and the conductor material in sintering is changed by changing the relative proportion of the lanthanum borocalcium glass A and B. The conductor material is selected from gold and silver paste.

[0042] The beneficial effects of the application are as follows:

[0043] The lanthanum borocalcium glass / alumina ceramic composite LTCC microwave dielectric material can achieve the performance adjustment of the LTCC microwave dielectric material without changing the production process, only by changing the amount of the lanthanum borocalcium glass powder with two different compositions and particle sizes in the LTCC flow slurry, so as to improve the sintering performance of the LTCC green ceramic material, enhance the adaptability of the LTCC green ceramic material to the conductor material, and optimize the mechanical and dielectric properties of the LTCC green ceramic material.

[0044] The present application can solve the problem of warping, delamination and metal wiring adhesion of the substrate material after sintering caused by the mismatching of the sintering characteristics of the substrate material and the slurry during the co-sintering of the LTCC device, improve the finished product quality and yield of the LTCC material, and can be widely applied in the field of high-frequency dielectric packaging. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0046] Figure 1 XRD pattern of the test block pressed by the lanthanum borocalcium glass A and lanthanum borocalcium glass B powder after 30 min of heat preservation at 700 DEG C.

[0047] Figure 2 XRD pattern of the test block pressed by the lanthanum borocalcium glass A and lanthanum borocalcium glass B powder after 30 min of heat preservation at 850 DEG C.

[0048] Figure 3 DSC pattern of the test block pressed by the two kinds of glass powder mixed according to the comparative examples and the examples at a heating rate of 10 DEG C / min.

[0049] Figure 4 HSM pattern of the test block pressed by the two kinds of glass powder mixed according to the comparative examples and the examples at a heating rate of 10 DEG C / min. DETAILED DESCRIPTION

[0050] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application.

[0051] Example 1

[0052] La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1%; and lanthanum borocalcium glass B having a composition of La2O3 45%, B2O3 36%, CaO 19%.

[0053] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to form a glass sheet to complete quenching. The glass sheet was crushed and sieved, and the crushed glass was placed in a ball mill tank, with alumina ceramic balls of 5 mm in diameter as grinding media, and water as solvent, at a material-to-liquid ratio of 1:1, and placed in a ball mill at a speed of 200 r / min to obtain a desired particle size. The milled glass slurry was poured into a tray, dried, and crushed for use. The particle size of the lanthanum borocalcium glass A was 1-3 μm (obtained by sieving), and the particle size of the lanthanum borocalcium glass B was 0.5-2 μm (obtained by sieving). The particle size of the alumina particles was 2-3 μm, which was obtained by using an air classifier.

[0054] The lanthanum borocalcium glass A, the lanthanum borocalcium glass B, and the alumina were added to a ball mill tank at a mass ratio of 47:3:50, and a plurality of alcohol, butanone, cyclohexanone, and terpineol were added as solvents, and an acrylic resin and ethyl cellulose were added as binders, and butyl phthalate was added as a plasticizer, and alumina ceramic balls were added as grinding media, and a roll mill was used to mix for 24 h to prepare a uniform slurry. After the slurry was degassed for 5-10 min, a casting machine was used to cast a green ceramic tape having a thickness of 100-150 μm, and a cutting machine was used to cut the green ceramic sheet. After the prepared green ceramic sheet was cut, demolded, and hot-pressed, it was sintered at 850°C for 30 min to obtain an LTCC substrate material. The solid content of the green ceramic was controlled to be 90%-95%.

[0055] Example 2

[0056] The lanthanum borocalcium glass A was melted according to a composition of La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1%; and the lanthanum borocalcium glass B was melted according to a composition of La2O3 45%, B2O3 36%, CaO 19%.

[0057] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to roll into glass sheets to complete quenching. The glass sheets were crushed and sieved, and the crushed glass was put into a ball mill tank, with alumina ceramic balls of 5 mm in diameter as grinding media, and water as solvent, at a material-liquid ratio of 1:1, and put into a ball mill at a speed of 200 r / min to grind to the required particle size. The ground glass slurry was poured into a tray, dried and crushed for use. The particle size of lanthanum calcium borate glass A was 1-3 μm, and the particle size of lanthanum calcium borate glass B was 0.5-2 μm. The alumina particles with a particle size of 2-3 μm were sieved out using an air classifier.

[0058] Lanthanum calcium borate glass A, lanthanum calcium borate glass B, alumina, alcohol, butanone, cyclohexanone, and pine oil alcohol were added into a ball mill tank at a mass ratio of 44:6:50, and the mixture was mixed for 24 h using a roller mill to prepare a uniform slurry. The slurry was degassed for 5-10 min, and then cast into a green ceramic tape with a thickness of 100-150 μm using a casting machine. The green ceramic sheet was cut and demolded, and then sintered at 850°C for 30 min to obtain an LTCC substrate material. The solid content of the green ceramic was controlled at 90%-95%.

[0059] Example 3

[0060] Lanthanum calcium borate glass A was prepared according to a composition of La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, and ZrO2 1%. Lanthanum calcium borate glass B was prepared according to a composition of La2O3 45%, B2O3 36%, and CaO 19%.

[0061] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to roll into glass sheets to complete quenching. The glass sheets were crushed and sieved, and the crushed glass was put into a ball mill tank, with alumina ceramic balls of 5 mm in diameter as grinding media, and water as solvent, at a material-liquid ratio of 1:1, and put into a ball mill at a speed of 200 r / min to grind to the required particle size. The ground glass slurry was poured into a tray, dried and crushed for use. The particle size of lanthanum calcium borate glass A was 1-3 μm, and the particle size of lanthanum calcium borate glass B was 0.5-2 μm. The alumina particles with a particle size of 2-3 μm were sieved out using an air classifier.

[0062] La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1% by weight; and lanthanum borocalcium glass B having a composition of La2O3 45%, B2O3 36%, CaO 19% by weight.

[0063] Example 4

[0064] La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1% by weight; and lanthanum borocalcium glass B having a composition of La2O3 45%, B2O3 36%, CaO 19% by weight.

[0065] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to be rolled into a glass sheet to complete quenching. The glass sheet was crushed and sieved, and the crushed glass was put into a ball mill tank. Alumina ceramic balls with a diameter of 5 mm were added as grinding media at a ball-to-material ratio of 1:2, and water was added as a solvent at a material-to-liquid ratio of 1:1. The mixture was ball-milled in a ball mill at a speed of 200 r / min until the desired particle size was obtained. The milled glass slurry was poured into a tray, dried, and crushed for use. The particle size of the lanthanum borocalcium glass A was 1-3 μm, and the particle size of the lanthanum borocalcium glass B was 0.5-2 μm. An air classifier was used to screen alumina particles with a particle size of 2-3 μm.

[0066] La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1% by weight; and lanthanum borocalcium glass B having a composition of La2O3 45%, B2O3 36%, CaO 19% by weight.

[0067] Example 5

[0068] La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, ZrO2 1% and La2O3 45%, B2O3 36%, CaO 19%.

[0069] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to be rolled into glass sheets to complete quenching. The glass sheets were crushed and sieved, and the crushed glass was put into a ball mill tank. Alumina ceramic balls with a diameter of 5 mm were added as grinding media at a ball-to-material ratio of 1:2, and water was added as a solvent at a material-to-liquid ratio of 1:1. The ball mill was operated at a speed of 200 r / min until the desired particle size was obtained. The milled glass slurry was poured into a tray, dried, and crushed for use. The particle size of the lanthanum borocalcium glass A was 1-3 μm, and the particle size of the lanthanum borocalcium glass B was 0.5-2 μm. An air classifier was used to screen out alumina particles with a particle size of 2-3 μm.

[0070] The lanthanum borocalcium glass A, the lanthanum borocalcium glass B, and alumina were added to a ball mill tank at a mass ratio of 35:15:50, and alcohol, butanone, cyclohexanone, and many kinds of terpilenol were added as solvents. Acrylic resin and ethyl cellulose were added as binders, and butyl phthalate was added as a plasticizer. Alumina ceramic balls were added as grinding media. The roll mill was used for mixing for 24 h to prepare a uniform slurry. After the slurry was degassed for 5-10 min, a casting machine was used to cast a green ceramic tape with a thickness of 100-150 μm, and a cutting machine was used to cut the green ceramic tape into green ceramic sheets. After the prepared green ceramic sheets were cut, demolded, and hot-pressed, sintering was performed at 850 °C for 30 min to obtain an LTCC substrate material. The solid content of the green ceramic was controlled to be 90%-95%.

[0071] Comparative Example 1

[0072] The lanthanum borocalcium glass A was melted according to a composition ratio of La2O3 32%, B2O3 40%, CaO 16%, P2O5 6%, SiO2 3%, Li2O 1%, Na2O 1%, and ZrO2 1%.

[0073] The glass raw materials were kept in a platinum crucible for 2 h to obtain a glass liquid, which was poured into a double-roller cooling mill to be rolled into glass sheets to complete quenching. The glass sheets were crushed and sieved, and the crushed glass was put into a ball mill tank. Alumina ceramic balls with a diameter of 5 mm were added as grinding media at a ball-to-material ratio of 1:2, and water was added as a solvent at a material-to-liquid ratio of 1:1. The ball mill was operated at a speed of 200 r / min until the desired particle size was obtained. The milled glass slurry was poured into a tray, dried, and crushed for use. The particle size of the lanthanum borocalcium glass A was 1-3 μm. An air classifier was used to screen out alumina particles with a particle size of 2-3 μm.

[0074] La2O3-B2O3-CaO glass A, alumina, alcohol, butanone, cyclohexanone, terpineol, acrylic resin, ethyl cellulose, butyl phthalate, alumina ceramic ball, and roll mill were mixed in a ball mill tank for 24 hours to prepare a uniform slurry. The slurry was degassed for 5-10 minutes and then cast into a green ceramic tape with a thickness of 100-150 μm using a casting machine. The green ceramic tape was cut into green ceramic pieces using a cutting machine. The green ceramic pieces were cut, demolded, and hot-pressed, and then sintered at 850°C for 30 minutes to obtain an LTCC substrate material. The solid content of the green ceramic was controlled to be 90-95%.

[0075] Comparative Example 2

[0076] La2O3-B2O3-CaO glass B was prepared in a ratio of La2O3 45%, B2O3 36%, and CaO 19%.

[0077] The glass raw materials were kept in a platinum crucible for 2 hours to obtain a glass liquid. The glass liquid was poured into a double-roller cooling mill to complete quenching. The glass pieces were crushed and sieved. The crushed glass was put into a ball mill tank, alumina ceramic balls with a diameter of 5 mm were added as a grinding medium at a ball-to-material ratio of 1:2, and water was added as a solvent at a material-to-liquid ratio of 1:1. The mixture was ball-milled in a ball mill at a speed of 200 r / min until the desired particle size was obtained. The milled glass slurry was poured into a tray, dried, and crushed for use. The particle size of the La2O3-B2O3-CaO glass B was 0.5-2 μm. An air classifier was used to screen alumina particles with a particle size of 2-3 μm.

[0078] La2O3-B2O3-CaO glass B, alumina, alcohol, butanone, cyclohexanone, terpineol, acrylic resin, ethyl cellulose, butyl phthalate, alumina ceramic ball, and roll mill were mixed in a ball mill tank for 24 hours to prepare a uniform slurry. The slurry was degassed for 5-10 minutes and then cast into a green ceramic tape with a thickness of 100-150 μm using a casting machine. The green ceramic tape was cut into green ceramic pieces using a cutting machine. The green ceramic pieces were cut, demolded, and hot-pressed, and then sintered at 850°C for 30 minutes to obtain an LTCC substrate material. The solid content of the green ceramic was controlled to be 90-95%.

[0079] The test method was as follows:

[0080] A D8-ADVANCE X-ray diffractometer produced by BRUKER, Germany, was used to test the phase composition of the glass samples of Comparative Example 1 and Comparative Example 2 after sintering at 700°C and 850°C, respectively. The X-ray diffractometer used a Cu target with a wavelength of 1.5406 A. The scanning range 2θ was 10-90°, the scanning time was 10° / min, the working voltage was 40 KV, and the working current was 150 mA. The results are shown in FIGS. 1 and 2. Figure 1 andFigure 2 Data.

[0081] DSC: The endothermic and exothermic curves of each glass powder were measured by using STA 449F3 differential scanning calorimeter produced by Germany NETZSCH company. The heating rate was 10℃ / min. The data were obtained as follows. Figure 3 Data.

[0082] The real-time sintering behavior of each glass powder compact sample during sintering was observed by using HM 867 high temperature imager produced by American TA company, and the volume change was recorded. The glass powder was pressed into Φ3mmx3mm cylindrical sample by using mold, placed on alumina ceramic gasket and put into high temperature imager for sintering, and the heating rate was 10℃ / min. The data were obtained as follows. Figure 4 Data.

[0083] The thermal expansion coefficient of each sintered substrate material was tested by using DIL 402PC thermal dilatometer produced by Germany NETZSCH company. The heating rate was 5℃ / min.

[0084] The dielectric constant and dielectric loss of each sintered substrate material were tested by using E5080B network analyzer produced by American KEYSIGHT company. The test frequency was 20GHz.

[0085] The tensile strength was tested by using MTS-Model E42 universal testing machine produced by American MTS company. The silver-plated copper wire was welded on the conductor material sintered on the surface of the substrate material, the copper wire was pulled by using the universal testing machine, and the average value of the force when the lead wire was pulled off from the substrate was used to represent the adhesion, i.e. the tensile strength. Refer to GB / T 17473.4-2008.

[0086] The size of each substrate material before and after sintering was measured by using Dongguan GOODVISION optical processing system, and the sintering shrinkage rate was calculated.

[0087] Compared with lanthanum calcium borate glass A, lanthanum calcium borate glass B contains more network extra body oxide La2O3, which can reduce the completeness of the glass network, reduce the softening temperature and crystallization temperature of the glass, and increase the crystallization speed of the glass. Therefore, in the DSC test results as shown in Figure 3 , the glass transition temperature and crystallization temperature of lanthanum calcium borate glass B are obviously lower than those of lanthanum calcium borate glass A, and the crystallization peak is more sharp and the crystallization is stronger. As shown in Figure 1 , after sintering at 700℃, the spectrum of lanthanum calcium borate glass A is still amorphous "steamed bun peak", indicating that no crystal phase is precipitated, while lanthanum calcium borate glass B has obvious crystallization peak, proving that it has been crystallized. In the five examples, with the increase of the content of lanthanum calcium borate glass B, the glass transition temperature of the sample decreases and the crystallization is enhanced.

[0088] Since the lanthanum borocalcium glass B has a lower glass softening temperature, the initial shrinkage temperature of Comparative Example 2 is obviously lower than that of Comparative Example 1 during the heating process as shown in Table 2. Figure 4 The initial shrinkage temperature of the five examples also decreases with the increase of the content of the lanthanum borocalcium glass B.

[0089] Table 1 Performance test results of Examples 1-5

[0090]

[0091] Table 2 Performance test results of Comparative Examples 1-2

[0092]

[0093] As can be seen from Tables 1 and 2, the drawing strength of Examples 1-5 is all above 2.2 kg, the initial softening sintering temperature is low, and the shrinkage rate in X / Y direction is small, so that when co-sintered with the conductor material, warping, delamination and the decrease of the metal wiring adhesion are not prone to occur. When only the lanthanum borocalcium glass A powder is used, the initial sintering shrinkage temperature is high, the metal wiring adhesion is decreased, and thus the drawing strength is poor; when only the lanthanum borocalcium glass B powder is used, the crystallization of the substrate material is too strong, which causes the substrate material to complete sintering too early, the glass powder in the conductor material is difficult to infiltrate the substrate, the pinning effect is poor, and the too early crystallization causes the shrinkage rate to be too small, which is mismatched with the shrinkage rate of the conductor material, resulting in poor metal wiring adhesion, low drawing strength, and reduced yield and product quality.

[0094] During the sintering process of the device, the conductor metal material starts to soften and sinter at a lower temperature. If the initial sintering temperature of the conductor material is too different from that of the substrate material, when the conductor material starts to sinter and shrink, the organic matter in the substrate material responsible for fixing and maintaining the green ceramic shape has been decomposed, and the glass has not yet softened to bond the ceramic powder aggregate, at this time the substrate strength is low, and is prone to warp and deform with the conductor material shrinkage; and when the conductor material is about to complete sintering and shrinkage, the substrate material only starts to soften and sinter, which is prone to cause the adhesion between the two to decrease. Reducing the initial sintering temperature of the substrate material makes it more matched with the sintering and shrinkage behavior of the conductor material, reduces the stress between the substrate and the conductor material, and improves the adhesion strength of the circuit metal wiring, which can improve the yield of the device sintering. At the same time, the sintering shrinkage rate of the substrate material is not prone to be too large, the circuit pattern is not prone to be unevenly distributed in the substrate, and the bottom surface of the substrate is in contact with the pad burning plate, so that the substrate is not prone to be deformed due to the uneven stress during the sintering process.

[0095] The alkali metal ion has a small radius and a strong polarization, and is prone to ion relaxation polarization; Si 4+ will perfect the glass network, inhibit crystallization, and increase the residual glass phase content of the sintered sample. Increasing the proportion of the lanthanum borocalcium glass B makes the alkali metal ion in the substrate material and Si 4+The dielectric constant and dielectric loss of the substrate material are reduced.

[0096] LTCC devices often need to weld silicon-based chips and other active devices, and use Kovar alloy and silicon-aluminum alloy for fixed packaging. These materials usually have a low coefficient of thermal expansion. Thermal stress caused by thermal expansion mismatch can easily lead to a significant reduction in the reliability of LTCC devices, so the LTCC substrate material needs to have a low coefficient of thermal expansion. The coefficients of thermal expansion of gold and silver are 14.2*10 -6 / ℃ and 19.5*10 -6 / ℃, respectively. Because the gold and silver conductive lines in the circuit are thin and fine, the stress caused by thermal expansion mismatch has little effect on the adhesion of the circuit.

[0097] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An LTCC microwave dielectric material, characterized in that, By mass percentage, it includes: 30%~50% lanthanum borosilicate glass A powder, 20% lanthanum borosilicate glass B powder (greater than 0 and less than or equal to 20%), and 48%~52% alumina powder. The particle size of the lanthanum borosilicate glass A powder is 1~3μm, and the particle size of the lanthanum borosilicate glass B powder is 0.5~2μm. By mass percentage, the composition of the lanthanum borosilicate glass A powder is: La2O3 30%~40%, B2O3 35%~50%, CaO 15%~25%, P2O5 0~10%, SiO2 0~10%, alkali metal oxides 1%~5%, and ZrO2 1~3%. The composition of the lanthanum borosilicate glass B powder, by mass percentage, is 37%~47% La2O3, 30%~40% B2O3, and 13%~23% CaO.

2. The LTCC microwave dielectric material according to claim 1, characterized in that, The composition of the lanthanum borosilicate glass A powder, by mass percentage, consists of La2O3 30%~38%, B2O3 35%~46%, CaO 15%~20%, P2O5 4~8%, SiO2 2~6%, alkali metal oxides 1%~5%, and ZrO2 1~3%. And / or, the composition of the lanthanum borosilicate glass B powder is, by mass percentage, 41%~47% La2O3, 33%~38% B2O3 and 15%~21% CaO.

3. The LTCC microwave dielectric material according to claim 1 or 2, characterized in that, By weight percentage, it includes: 34%~46% lanthanum borosilicate glass A powder, 4%~16% lanthanum borosilicate glass B powder, and 50% alumina powder; And / or, the alumina powder is α-Al2O3 with a particle size of 2~3μm.

4. The LTCC microwave dielectric material according to claim 3, characterized in that, The alumina powder is sieved to the required ceramic powder particle size using an air classifier.

5. The LTCC microwave dielectric material according to any one of claims 1, 2, and 4, characterized in that, The preparation method of the lanthanum boron calcium glass A powder includes: using La2O3, H3BO3, CaCO3, Ca3(PO4)2, SiO2, Na2CO3, Li2CO3, and ZrO2 as raw materials, weighing them in proportion and mixing them thoroughly, then melting and quenching to obtain lanthanum boron calcium glass A, and then crushing and grinding the lanthanum boron calcium glass A to obtain lanthanum boron calcium glass A powder. And / or, the preparation method of the lanthanum borosilicate glass B powder includes: using La2O3, H3BO3 and CaCO3 as raw materials, weighing and mixing them in proportion, then melting and quenching to obtain lanthanum borosilicate glass B, and crushing and grinding the lanthanum borosilicate glass B to obtain lanthanum borosilicate glass B powder.

6. The LTCC microwave dielectric material according to claim 3, characterized in that, The preparation method of the lanthanum boron calcium glass A powder includes: using La2O3, H3BO3, CaCO3, Ca3(PO4)2, SiO2, Na2CO3, Li2CO3, and ZrO2 as raw materials, weighing them in proportion and mixing them thoroughly, then melting and quenching to obtain lanthanum boron calcium glass A, and then crushing and grinding the lanthanum boron calcium glass A to obtain lanthanum boron calcium glass A powder. And / or, the preparation method of the lanthanum borosilicate glass B powder includes: using La2O3, H3BO3 and CaCO3 as raw materials, weighing and mixing them in proportion, then melting and quenching to obtain lanthanum borosilicate glass B, and crushing and grinding the lanthanum borosilicate glass B to obtain lanthanum borosilicate glass B powder.

7. The LTCC microwave dielectric material according to claim 5, characterized in that, The melting and quenching process includes: first holding the glass at 1300~1500℃ for 1.5-2.5h, then pouring the melted glass into a double-roll cooling mill for quenching and rolling into glass sheets; And / or, the crushing and grinding of the lanthanum borosilicate glass A includes: initially crushing the lanthanum borosilicate glass A and passing it through a 50-mesh sieve, and then grinding it into lanthanum borosilicate glass A powder with a particle size of 1~3μm using a ball milling method; And / or, the crushing and grinding of the lanthanum borosilicate glass B powder includes: initially crushing the lanthanum borosilicate glass B and passing it through an 80-mesh sieve, and then grinding it into lanthanum borosilicate glass B powder with a particle size of 0.5~2μm using a ball milling method.

8. The LTCC microwave dielectric material according to claim 6, characterized in that, The melting and quenching process includes: first holding the glass at 1300~1500℃ for 1.5-2.5h, then pouring the melted glass into a double-roll cooling mill for quenching and rolling into glass sheets; And / or, the crushing and grinding of the lanthanum borosilicate glass A includes: initially crushing the lanthanum borosilicate glass A and passing it through a 50-mesh sieve, and then grinding it into lanthanum borosilicate glass A powder with a particle size of 1~3μm using a ball milling method; And / or, the crushing and grinding of the lanthanum borosilicate glass B powder includes: initially crushing the lanthanum borosilicate glass B and passing it through an 80-mesh sieve, and then grinding it into lanthanum borosilicate glass B powder with a particle size of 0.5~2μm using a ball milling method.

9. An LTCC green ceramic, characterized in that, It is prepared using the LTCC microwave dielectric material as the main raw material according to any one of claims 1-8.

10. The LTCC green ceramic according to claim 9, characterized in that, The preparation method of LTCC green ceramic tape includes: mixing lanthanum borosilicate glass A powder, lanthanum borosilicate glass B powder, alumina powder, organic binder, solvent and plasticizer evenly to obtain casting slurry, and casting the casting slurry after degassing treatment to obtain LTCC green ceramic tape; And / or, the thickness of the LTCC green ceramic tape is 100~150μm, and the solid content is >90%; And / or, the solvent includes at least two of alcohol, methyl ethyl ketone, cyclohexanone, and terpineol; the organic binder includes at least one of acrylic resin and ethyl cellulose; and the plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate.

11. An LTCC substrate material, characterized in that, The green ceramic described in claim 9 or 10 is cut, demolded, hot-pressed, and then sintered to obtain LTCC substrate material.

12. The LTCC substrate material according to claim 11, characterized in that, The dielectric loss of the LTCC substrate material is less than 1×10⁻⁶. -3 Shrinkage rate in the X / Y direction is less than 8.5%; coefficient of thermal expansion is less than 6 ppm / ℃; tensile strength is greater than 2.20 kg.

13. A method for adjusting the performance of LTCC microwave dielectric materials, characterized in that, Based on the properties of the conductor material to be matched, the ratio of lanthanum borosilicate glass A powder to lanthanum borosilicate glass B powder in the LTCC green ceramic is adjusted to control the compatibility between the LTCC green ceramic and the conductor material during sintering. The LTCC green ceramic is prepared using the LTCC microwave dielectric material as the main raw material according to any one of claims 1-8.

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