JPH026203B2 - - Google Patents
Info
- Publication number
- JPH026203B2 JPH026203B2 JP55007311A JP731180A JPH026203B2 JP H026203 B2 JPH026203 B2 JP H026203B2 JP 55007311 A JP55007311 A JP 55007311A JP 731180 A JP731180 A JP 731180A JP H026203 B2 JPH026203 B2 JP H026203B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature coefficient
- temperature
- negative
- ferrite
- value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229910000859 α-Fe Inorganic materials 0.000 claims description 17
- 230000035699 permeability Effects 0.000 claims description 11
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 6
- 229910015902 Bi 2 O 3 Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 3
- 239000000696 magnetic material Substances 0.000 claims description 2
- 239000000654 additive Substances 0.000 claims 1
- 239000003990 capacitor Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000001354 calcination Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
- H01F1/342—Oxides
- H01F1/344—Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
Landscapes
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Hard Magnetic Materials (AREA)
- Soft Magnetic Materials (AREA)
- Magnetic Ceramics (AREA)
Description
本発明は、高周波で使用されるフエライト磁芯
の温度特性の改良に関するものである。
テレビ、ラジオさらには移動無線等の高周波通
信回路に用いられる磁芯コイルはインダクタンス
調整のための小型機能部品として欠かせないもの
となつている。通常この磁芯コイルはフエライト
コア及びボビンに巻線されたコイルとよりなり、
この組合せで任意の値のインダクタンスを得るよ
うに設計されている。
この磁芯コイルに要求される特性としては
(1) コイルとフエライトコアの組合せより適切な
値のインダクタンスが得られること。
(2) 周囲の温度変化に対し安定であること。
が必要である。特に(2)の温度変化に対する特性の
安定性については、磁芯コイルの小型化と相まつ
て僅かのインダクタンスの変化が回路全体に大き
な影響を及ぼすので特に重要である。温度変化に
対して特性を安定させる方法として従来より採用
されている方法は、コンデンサと磁芯コイルの組
合せで回路が構成されるため、これらを合せた温
度係数が小さくなるように材質を選定するもので
あつた。すなわち一般にコンデンサの容量は負の
温度係数を有するため、これに対応して初透磁率
の温度係数が正でかつ極めて小さな値の（通常20
〜100×10-6／℃）フエライトコアを使用した磁
性コイルとし回路全体の温度係数を零に近いもの
とするという方法である。しかしながらこのよう
にして得られる回路全体の温度係数は回路を構成
する他の部品の温度係数が正であるため結局総和
としては正のものしか実現出来ず満足出来るもの
ではなかつた。この現状は使用周波数が高くなる
につれ一層大きな問題となつている。このような
従来法による欠点を解決するにはコンデンサの温
度係数をさらに大きな負のものとすることが考え
られるが、コンデンサの温度係数を制御すること
は非常に困難である。従つて、フエライトコアの
温度係数を正のものより負のものとすることが有
効な方法となる。通常高周波用フエライトコアは
損失を小さくするため高抵抗のものとする必要が
あり、Niフエライトを基本にしてこれに第２、
第３の元素を置換したものが使用されているが、
この場合高周波におけるＱ値を大きくならしめる
ため少量のCoを置換することが不可欠である。
しかしながらこのような従来の組成で製造され
たものでは、第１図に示す一般的な材料の初透磁
率の温度変化のように、非常に狭い温度範囲でし
か負の温度係数を実現できず実用に供することは
出来ない。
本発明者は、特願昭53−72567及び特願昭53−
72568により、実用範囲で初透磁率が負の温度係
数を有するフエライトを提案した。上記の特許願
の中で温度係数は、−20℃から＋60℃の間で−50
〜−80（×10-6）の値であつた。
本発明は、Fe，Al，Ni，Coよりなる組成のフ
エライトに少量のBi2O3およびSiO2を添加し、か
つ組成範囲を詳細に検討することにより広い温度
範囲にわたつて初透磁率の温度係数が負であり、
かつその温度係数の絶対値の大きなフエライトコ
アを実現し、回路全体の温度補償を理想的なもの
としようとするものである。
以下実施例により詳細に説明する。
実施例 １
化学式でNi0.98 Co0.02 Fe2−αAlαO4ただし
α＝０，0.2，0.4となるようにNiO，Co2O3，
Fe2O3，Al2O3を秤量し、これにBi2O3を1.0wt％、
SiO2を0.5wt％添加した粉体を水を媒体としてボ
ールミル中にて24時間混合した。ミル中より取り
出し水分を蒸発乾固させたる後大気中にて800〜
1000℃の温度で２時間仮焼を施し、更に水を媒体
としてボールミル中にて24時間粉砕を行つた。こ
の粉砕粉に1.0wt％のPVAを加えライカイ機で造
粒後60メツシユのふるいで分級を行つた。この造
粒粉を金型中で外径36mm内径24mm高さ３mmのリン
グ形状に成形し、大気中にて1100℃×３時間の焼
成を施した。この試料の初透磁率の温度変化を第
２図および第３図に、特性値を第１表に掲げた。
The present invention relates to improving the temperature characteristics of ferrite magnetic cores used at high frequencies. Magnetic core coils used in high frequency communication circuits such as televisions, radios, and even mobile radios have become indispensable as small functional components for adjusting inductance. This magnetic core coil usually consists of a ferrite core and a coil wound around a bobbin.
This combination is designed to obtain an arbitrary value of inductance. The characteristics required of this magnetic core coil are (1) that an appropriate value of inductance can be obtained from the combination of the coil and ferrite core; (2) Be stable against changes in ambient temperature. is necessary. In particular, (2) stability of characteristics with respect to temperature changes is particularly important because, coupled with the miniaturization of the magnetic core coil, a slight change in inductance has a large effect on the entire circuit. The conventional method of stabilizing characteristics against temperature changes is to select materials so that the combined temperature coefficient of the circuit is small, since the circuit is composed of a combination of a capacitor and a magnetic core coil. It was hot. In other words, since the capacitance of a capacitor generally has a negative temperature coefficient, the temperature coefficient of the initial magnetic permeability is correspondingly positive and extremely small (usually 20
This method uses a magnetic coil using a ferrite core (~100×10 -6 /°C) to make the temperature coefficient of the entire circuit close to zero. However, since the temperature coefficient of the entire circuit obtained in this way is positive because the temperature coefficients of the other components constituting the circuit are positive, in the end only a positive value can be achieved as a summation, which is not satisfactory. This current situation is becoming a more serious problem as the frequencies used become higher. In order to solve these drawbacks of the conventional method, it is conceivable to make the temperature coefficient of the capacitor even more negative, but it is very difficult to control the temperature coefficient of the capacitor. Therefore, an effective method is to make the temperature coefficient of the ferrite core negative rather than positive. Normally, ferrite cores for high frequencies need to have high resistance to reduce loss, so Ni ferrite is used as a base, and second,
Substituting a third element is used, but
In this case, it is essential to replace a small amount of Co in order to increase the Q value at high frequencies. However, with products manufactured with such conventional compositions, a negative temperature coefficient can only be achieved in a very narrow temperature range, as shown in Figure 1, which shows the temperature change in initial permeability of common materials. It cannot be offered to The inventor of the present invention
72568, we proposed a ferrite whose initial magnetic permeability has a negative temperature coefficient within a practical range. In the above patent application, the temperature coefficient is -50°C between -20°C and +60°C.
The value was ~-80 (×10 -6 ). In the present invention, by adding a small amount of Bi 2 O 3 and SiO 2 to ferrite with a composition of Fe, Al, Ni, and Co, and by studying the composition range in detail, it is possible to increase the initial permeability over a wide temperature range. the temperature coefficient is negative;
The aim is to realize a ferrite core with a large absolute value of its temperature coefficient, and to idealize the temperature compensation of the entire circuit. This will be explained in detail below using examples. Example 1 The chemical formula is Ni0.98 Co0.02 Fe2−αAlαO4 However, NiO, Co 2 O 3 ,
Weigh Fe 2 O 3 and Al 2 O 3 , and add 1.0wt% Bi 2 O 3 to it.
Powder to which 0.5 wt% of SiO 2 was added was mixed for 24 hours in a ball mill using water as a medium. After taking it out from the mill and evaporating the water to dryness, it was heated to 800 ~
Calcination was performed at a temperature of 1000° C. for 2 hours, and further pulverization was performed for 24 hours in a ball mill using water as a medium. 1.0wt% of PVA was added to the pulverized powder, which was granulated using a Raikai machine, and then classified using a 60-mesh sieve. This granulated powder was molded into a ring shape with an outer diameter of 36 mm, an inner diameter of 24 mm, and a height of 3 mm in a mold, and fired at 1100° C. for 3 hours in the air. The temperature changes in the initial magnetic permeability of this sample are shown in Figures 2 and 3, and the characteristic values are listed in Table 1.
【表】
第２図は、α＝0.4の実施例の初透磁率の温度
変化のグラフであり、第３図は、Alの添加量に
よるΔμi／μiの変化を示す図である。
以上のように、本発明による高周波用材料は、
−30℃〜180℃までの非常に広い範囲に渡つて負
の係数を示しており、その値は−20℃〜＋60℃の
間で−140〜−150（×10-6／℃）であつた。ここ
で温度係数の値は、以下の式で定義した。
μi（at60℃）−μi（at−20℃）／μi2（at20℃）×
80
以上の実施例に示したごとく本発明によるフエ
ライトコアは初透磁率が一様な負の変化を示し、
しかも係数の絶対値が大きく、これを負の温度係
数を有するコンデンサと組み合わせて使用すれ
ば、他の回路部品の正の温度係数と打ち消しあい
回路全体の温度係数を零とすることが可能であ
る。あるいはコンデンサを使用しない回路におい
ても、他の回路部品の正の温度係数とフエライト
コアの負の係数との総和がより一層理想的なもの
となる。このように本発明による負の温度係数を
有するフエライトコアを使用すれば回路の温度補
償を理想的なものと出来、その工業的価値には計
り知れないものがある。
なお特許請求の範囲において組成を限定した理
由は以下による。まず、一般にフエライトの化学
式は、MeFe2O4（Meは２価の金属イオン）と表
わされるから、ｘ＋ｙ＋ｚ＝３とした。次に、
Fe量については、ｚ＝1.8より少ないと高周波で
のＱ値が低下し、逆にｚ＝2.19より多いと所謂磁
場劣化の現象が著しくなり実用的でなくなる。
Ni量については、ｘ＝0.8より少ないとFe量同様
Ｑ値が低下し、ｘ＝1.19より多すぎると焼結性を
極端に阻害するため密度が低下し製品の強度が弱
くなる。Co量については、ｙ＝0.01より少ないと
Ｑ値が低下し、ｙ＝0.03より多すぎると第２図に
示した２次ピークが高温側に大きく移動するため
負の温度係数の初透磁率とすることができない。
さらにBi2O3量が4wt％より多すぎるとＱ値の低
下を生じ、SiO2量が3wt％より多すぎると焼結性
が損われ製品強度が低下する。また、Bi2O3及び
SiO2の量が請求範囲より少ないと温度係数が負
より正に転じてしまい目的のものが得られない。
さらに第１表に基いて、αと温度係数の関係を
表わすと第４図の様になる。この第４図より明ら
かに、α＝0.05であると温度係数は−100×
10-6／℃程度を期待できる。また、Fe2O3、NiO
等のAl2O3を除く成分中に不純物として含まれ得
るAl量は、一般に式量にして高々0.02である。ま
た、α≧0.5では、焼結性が損われ、製品強度が
低下する。これを、焼結温度を上げる事により改
善しようとすると、損失が大きくなり実用的でな
くなる。従つて、0.05≦α≦0.4とする事により、
温度係数が負であり、かつその温度係数の絶対値
の大きな高周波磁性材料を得ることができる。
更につけ加えるならば、本発明によるフエライ
トは、これを構成する６種類の基本成分が複雑に
関連して始めて負の温度係数を実現出来るもので
あり、上記範囲外においては、実用範囲である−
20〜80℃の温度範囲全域で温度係数を一様に負に
することが出来ず実用的でない。[Table] FIG. 2 is a graph of the temperature change in initial magnetic permeability of the example in which α=0.4, and FIG. 3 is a graph showing the change in Δμi/μi depending on the amount of Al added. As described above, the high frequency material according to the present invention is
It shows a negative coefficient over a very wide range from -30°C to 180°C, and its value is -140 to -150 (×10 -6 /°C) between -20°C and +60°C. Ta. Here, the value of the temperature coefficient was defined by the following formula. μi (at60℃) − μi (at−20℃) / μi 2 (at20℃) ×
80 As shown in the above examples, the ferrite core according to the present invention exhibits a uniform negative change in initial magnetic permeability,
Moreover, the absolute value of the coefficient is large, and if this is used in combination with a capacitor that has a negative temperature coefficient, it cancels out the positive temperature coefficient of other circuit components, making it possible to reduce the temperature coefficient of the entire circuit to zero. . Alternatively, even in a circuit that does not use a capacitor, the sum of the positive temperature coefficients of other circuit components and the negative coefficient of the ferrite core becomes even more ideal. As described above, by using the ferrite core having a negative temperature coefficient according to the present invention, the temperature compensation of the circuit can be made ideal, and its industrial value is immeasurable. The reason for limiting the composition in the claims is as follows. First, since the chemical formula of ferrite is generally expressed as MeFe 2 O 4 (Me is a divalent metal ion), x+y+z=3. next,
Regarding the amount of Fe, when z is less than 1.8, the Q value at high frequencies decreases, and on the other hand, when z is more than 2.19, the so-called magnetic field deterioration phenomenon becomes significant, making it impractical.
Regarding the amount of Ni, if x is less than 0.8, the Q value will decrease like the amount of Fe, and if it is more than x = 1.19, the sinterability will be extremely inhibited, resulting in a decrease in density and weakening of the strength of the product. Regarding the amount of Co, if it is less than y = 0.01, the Q value will decrease, and if it is more than y = 0.03, the secondary peak shown in Figure 2 will largely shift to the high temperature side, resulting in an initial permeability with a negative temperature coefficient. Can not do it.
Furthermore, if the amount of Bi 2 O 3 is too large than 4 wt%, the Q value will be lowered, and if the amount of SiO 2 is too large than 3 wt%, the sinterability will be impaired and the strength of the product will be reduced. Also, Bi 2 O 3 and
If the amount of SiO 2 is less than the claimed range, the temperature coefficient will change from negative to positive and the desired result will not be obtained. Furthermore, based on Table 1, the relationship between α and temperature coefficient is expressed as shown in FIG. It is clear from this figure 4 that when α=0.05, the temperature coefficient is -100×
We can expect a temperature of around 10 -6 /℃. Also, Fe 2 O 3 , NiO
The amount of Al that can be contained as an impurity in components other than Al 2 O 3 is generally at most 0.02 in formula weight. Furthermore, when α≧0.5, sinterability is impaired and product strength is reduced. If an attempt is made to improve this by increasing the sintering temperature, the loss will increase, making it impractical. Therefore, by setting 0.05≦α≦0.4,
A high frequency magnetic material having a negative temperature coefficient and a large absolute value of the temperature coefficient can be obtained. In addition, the ferrite according to the present invention can only achieve a negative temperature coefficient when the six types of basic components that make up the ferrite interact in a complex manner, and outside the above range, it is within the practical range.
It is not practical because the temperature coefficient cannot be made uniformly negative over the entire temperature range of 20 to 80°C.
第１図は、通常得られる材料の初透磁率の温度
変化を示したグラフであり、第２図は、本発明に
係る一実施例の初透磁率の温度変化のグラフであ
り、第３図は、Al2O3の添加量によるΔμi／μiの
変化を示す図であり、第４図は、αと温度係数と
の関係を示す図である。
FIG. 1 is a graph showing a temperature change in the initial magnetic permeability of a normally obtained material, FIG. 2 is a graph showing a temperature change in the initial magnetic permeability of an example of the present invention, and FIG. FIG. 4 is a diagram showing the change in Δμi/μi depending on the amount of Al 2 O 3 added, and FIG. 4 is a diagram showing the relationship between α and temperature coefficient.
Claims (1)
≦1.19，0.01≦ｙ≦0.03，1.8≦ｚ≦2.19，0.05≦
α≦0.4でｘ＋ｙ＋ｚ＝３）で表わされる組成に
添加物としてBi2O3，SiO2をそれぞれ0.2≦Bi2O3
≦4wt％，0.2≦SiO2≦3wt％の範囲内で含有し焼
結してなるフエライトで初透磁率の温度係数が−
20〜＋80℃の範囲内で一様に負であることを特徴
とする高周波磁性材料。1 Chemical formula NixCoyFez−αAlαO 4 (0.8≦x
≦1.19, 0.01≦y≦0.03, 1.8≦z≦2.19, 0.05≦
Bi 2 O 3 and SiO 2 are added as additives to the composition expressed by
Ferrite containing ≦4wt%, 0.2≦SiO 2 ≦3wt% and sintered has a temperature coefficient of initial magnetic permeability of -
A high frequency magnetic material characterized by being uniformly negative within the range of 20 to +80°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP731180A JPS56104411A (en) | 1980-01-24 | 1980-01-24 | High frequency ferrite with negative temperature coefficient |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP731180A JPS56104411A (en) | 1980-01-24 | 1980-01-24 | High frequency ferrite with negative temperature coefficient |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56104411A JPS56104411A (en) | 1981-08-20 |
| JPH026203B2 true JPH026203B2 (en) | 1990-02-08 |
Family
ID=11662451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP731180A Granted JPS56104411A (en) | 1980-01-24 | 1980-01-24 | High frequency ferrite with negative temperature coefficient |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS56104411A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03297101A (en) * | 1990-02-28 | 1991-12-27 | Toshiba Corp | Power resistor and manufacture thereof |
-
1980
- 1980-01-24 JP JP731180A patent/JPS56104411A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56104411A (en) | 1981-08-20 |
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