CN101226811A - Water-based casting film-forming preparation technique for Mn-Zn ferrite - Google Patents

Abstract

The invention makes an introduction in terms of successful experiences of masking technique of Mn-Zn ferrite material, in an attempt to jointly explore a way for manufacturing inductance of Mn-Zn ferrite films. Along with the development of electronic equipment in the direction of miniaturization, networking and multimedia, the development of miniaturization of the electronic equipment progress with each passing day and multilayer chip transformers, BMI filters and EMI beads are developed successively, which breaks through the bottleneck of the development of chip inductors. Thin-film inductors made of international materials achieve rapid development, especially thin-film inductors made of Mn-Sn ferrite material achieve some development in Japan and at home. Recently, a plurality of enterprises show keen interests on the thin-film inductors made of Mn-Sn ferrite material, and further the manufacture of the inductance of the thin-film inductors depends on the film technique.

Description

Mn-Zn ferrite water-based casting film-forming preparation technique

Along with electronics miniaturization, the fast development of networking and multimedia direction, making rapid progress of electronic devices and components miniaturization development, pellet resistance, flaky electric capacity is produced in a large number in the many enterprises of China, have the pellet inductor slower development only, then, along with the multilayer sheet type transformer, the turn up of BMI filter and electromagnetic interface bead array, pellet inductor has entered brand-new developing period, the manufacturing of pellet inductor be unable to do without magnetic material, the wherein most widely used Ni of being CuZn soft magnetic ferrite also claims the LTCF technology, makes for MnZn ferrite material that pellet inductor is rare makes inquiries, and the present invention does an introduction with regard to the technology of preparing of manganese-zinc ferrite body thin film.

(1) preparation of ferrite powder

In the recent period, along with globalization energy supply anxiety, price is constantly up, the reduction energy consumption per unit of output value becomes the necessary technology measure in each product manufacture, therefore present domestic most of ferrite manufacturing enterprise, dry technology for production is all adopted in preparation to manganese-zinc ferrite powder, and its technology mixes → pre-burning → vibration → sand milling → mist projection granulating for batching → vibratory milling.Particularly the fineness of the powder after the pre-burning after vibration can reach≤1 μ, and through moulding, behind the sintering, its material property all can reach the material horizontal of other explained hereafter.Therefore be to meet technological requirement fully with the ferrite powder of this explained hereafter as the powder of casting film-forming.

(2) selection of flow casting molding method

Current domestic casting film-forming technology roughly is divided three classes, and does an introduction with regard to the excellence of the whole bag of tricks below.

(1) non-aqueous tape-casting film build method

This technology all adopts organic solvent, the mixed curtain coating slurry that makes of organic substance and ceramic powder, and the film of reparation technology required thickness on casting machine then, technology comparative maturity diaphragm structure is even, and strength and toughness is good, uses for many years in industrial production.But use large amount of organic in the curtain coating process, production cost height, discharge of noxious gases cause environmental pollution serious.

(2) aqueous gel tape casting process film build method

The aqueous gel tape casting process moulding process mainly is Tsing-Hua University's colloidal formation experimental group research and development, the slurry of aqueous gel tape casting process moulding is prepared by components such as ceramic powders, organic monomer, crosslinking agent, solvent, dispersant, plasticiser, initator, catalyst, behind the flow casting molding between 40 ℃ ~ 80 ℃ the trigger monomer polymerization reaction, polymer forms network configuration, make the slip film-forming, reach the moulding purpose.The film strength height of this explained hereafter, good toughness.But this technology must be under inert gas shielding owing to oxygen inhibition, and therefore drying and forming-film also increases technique controlling difficulty and production cost.Because the organic substance that adds is many, and environment is also had certain pollution.At present, this technology is in laboratory stage, and suitability for industrialized production is still needed and further groped.

(3) method for forming water-base casting

This method mainly is that solvent adds organic solvent with water, dispersant, plasticizer, binding agent, defoamer, is mixed with the slip of curtain coating, and slip preparation and casting technique intensity and toughness simple, diaphragm also can reach technological requirement, and the storage of can curling.But because evaporation of water speed is slower, in dry run diaphragm curl easily, defectives such as distortion, cracking, but low production cost, and low in the pollution of the environment, technological operation is simple, meets the economic development trend of current environmental protection and energy saving.

Comprehensive above three kinds of flow casting molding methods analysts are seen, just should pay attention to the environmental protection and energy saving principle of product processes from the new product development initial stage.

We have finally selected method for forming water-base casting in order to make the plain embryo of manganese-zinc ferrite body thin film.Defective as for method for forming water-base casting can take suitable technical measures to solve in the product development progressive process.

(3) water base casting process prepares ferrite film

Water-based tape casting legal system film, the existing application is same in the production of China's ceramic substrate, makes the manganese-zinc ferrite body thin film and also can use the method.

(1) binding agent

Binding agent is the critical material of ferrite system film.What this paper selected is nontoxic polyvinyl alcohol.

Polyvinyl alcohol is a kind of purposes high molecular weight water soluble polymer quite widely, nontoxic, has unique strong cohesive property, flatness, oil resistance, its good film-forming property is in other material, relatively poor because of containing hydroxyl stem (OH) event water resistance in its composition, but can improve its resistance to water through special processing, we divide the film dissolving situation (seeing the following form) in water made with polyvinyl alcohol of rolling over again

Table (one)

The kind project	The dissolving water temperature	The beginning dissolution time	Complete dissolution time
				The molten film of normal temperature	25℃	0.5 divide	15 minutes
In warm molten film	65℃	0.5 divide	18 minutes
				The molten film of high temperature	Do not dissolve fully below 40 ℃
	Dissolving fully more than 85 ℃

According to last table analysis, we can select suitable polyvinyl alcohol quality as adhesive fully, make the film behind its flow casting molding.Water insoluble at normal temperatures, be printing conductive slip and make multilayer ferrite inductance device and created advantage on the ferrite diaphragm later on like this, same, also can in PVA solution, add the resistance to water that modifier improves polyvinyl alcohol film,

(2) dispersant

In curtain coating slurry is made, what we adopted is star ball mill (sand mill), carry out the further levigate of ferrite powder, therefore do not unite to mix dispersant, allow dispersant adsorption at powder surface in order to obtain thinner powder (usually about 0.8 μ), weaken the interaction of powder greatly, avoid the powder conglomeration, strengthen grinding effect, it is levigate to help ferrite powder, increase the flowability of slip, therefore dispersant is absolutely necessary in making ferrite curtain coating slurry process.We select the triethanolamine of environment-friendly type equally.

(3) plasticizer

Adding plasticising machine can make slurry at room temperature have better flowability and not condense in curtain coating slurry is made, and powder granule is played lubrication, is convenient to casting film-forming.What we adopted is nontoxic glycerol equally, and glycerol not only makes the slip flowability improve after adding, and after the casting film-forming drying, the film embryo very easily separates with matrix.

(4) organic solvent

Organic solvent mainly is that dissolving is added on the organic substance in the slip.I once used the mixed solvent of alcohol and butanone, and the additive that uses because of us is solution, therefore added organic solvent and had little significance.The alternative water of alcohol can suitably be regulated rate of drying behind the casting film-forming as solvent.But butanone adding meeting reacts with PVA and generates the acetal thing, and the improper meeting of addition makes dry back film strength and toughness variation.

By the function analysis to the various additives in the ferrite film forming slip, we have established optimum process scheme such as figure below of manganese-zinc ferrite flow casting molding.

Concrete technical recipe sees Table (two):

Title material	Effect	Percentage by weight %
			The Mn-Zn ferrite powder	Main body	50～65
Water, ethanol,	Solvent	25～35
			Triethanolamine, phosphoric acid fat	Dispersant	0.5～1.0
Polyvinyl alcohol,	Adhesive	20～30
			Glycerol	Plasticizer	0.5～1.0
Tbp, alcohols mixture	Defoamer	0.2～0.5

More than prescription can be adjusted according to the flowability of material oar and the thickness of film.The sand milling time in the technical process can suitably be adjusted by experimental result.The milling time weak point is unfavorable for that the levigate and additive of powder is evenly mixed, and the long impurity content that increases easily in the slurry of milling time influences the quality behind the material sintering.

Add as less under film strength and the toughness prerequisite guaranteeing for the addition of dispersant and plasticizer,, increase the density of Ferrite Material so that improve the solid content of film, be beneficial to the material sintering after performance improve.

Conclusion:

Should aqueous tape casting forming system film be a kind of both environmental protection, energy-conservation a kind of good film build method, be worthy to be popularized, its technological operation is simple, production cost is low, low in the pollution of the environment, domestic existing many enterprises produce ceramic substrate in a large number with the method, deeply convince that the ferrite film inductance will be developed rapidly in the near future.

List of references:

(1) manufacture method of the manufacture method of 11-273979 soft magnetic ferrite powder and laminated chip inducer

(2) publication number CN1370758A molding process of water-thinned ceramic slurry gel 2002.9.25

(3) method of a publication number CN1390808A preparing ceramic sheet by water-base doctor blading, 2003.1.15

(4) method of the patent No. 02125213.0 process for preparing ceramic sheet from emulsoid system by water-base doctor blading.

Claims (4)

1. the water-based casting film-forming preparation technique of the present invention's employing is different from non-aqueous tape-casting film forming and aqueous gel tape casting process film technique.Its main feature be with water as primary solvent, do not use the organic solvent that butanone etc. has stimulates peculiar smell, rejected organic substances such as crosslinking agent, catalyst, initator in the prescription, make technological process and prescription effectively simple, production cost is low.

2. the organic substance that uses in this prescription is environment-friendly type, example: binding agent adopts nontoxic, and good polyvinyl alcohol, the plasticizer of filming performance selected glycerol, all do not adopt the organic substance that contains benzene.

3. casting film-forming is dry only needs general heat drying device to need not with initator, uv photopolymerization film forming and nitrogen protection drying device, and technology is simple, is easy to control.

4. at last technological process of the present invention and prescription are required to maintain secrecy.