JP4667882B2 - High thermal conductivity compound - Google Patents

Description

  The present invention relates to a high thermal conductivity compound having an extremely high thermal conductivity.

  Among semiconductor components used in electronic devices, there are components that generate heat during use, such as a CPU for a computer and a power semiconductor for power control. In order to protect these semiconductor components from heat and to function normally, there is a method of conducting the generated heat to a heat radiating component such as a heat sink to dissipate heat. The thermally conductive compound is applied between the semiconductor component and the heat radiating component so that the semiconductor component and the heat radiating component are in close contact with each other, and is used to increase heat conduction. The thermal conductivity of these joints is better as the thermal conductivity of the thermal conductive compound is higher, and is higher as the coating property is better (the thinner the coating film, the higher the adhesion). In recent years, the performance of computers has been particularly improved, and a thermal conductive compound having a high thermal conductivity has been demanded as a heat dissipation measure for CPUs.

A thermal conductive compound is a grease-like composition having an increased thermal conductivity by dispersing a large amount of a filler having a high thermal conductivity in a base oil. As the filler, metal oxides such as zinc oxide and aluminum oxide, nitrides such as silicon nitride, aluminum nitride and boron nitride, and metal powders such as aluminum, copper and silver are used. Among these, metal powders such as aluminum, copper, and silver have extremely high thermal conductivity, and may be used as a filler for higher thermal conductivity compounds (see Patent Document 1).
JP 2000-63873 A

However, although metal powders such as aluminum, copper, and silver are highly heat-conductive, they are relatively soft materials, and therefore, metal particles may be crushed in a roll mill treatment process during manufacturing. When the particles are crushed, the consistency of the compound is lowered, and the compound may not be prepared. A technique for improving the crushed is desired.

Further, the thermal conductivity of the thermally conductive compound increases as the amount of the filler increases. However, if the amount of the filler is too large, the consistency decreases and sufficient coatability may not be obtained. In this case, there is a possibility that the thermal conductivity is lowered by increasing the film thickness of the coating film or mixing bubbles. Therefore, there is a demand for a technique that can increase the amount of filler while maintaining a high consistency and good coatability.
An object of the present invention is to provide a heat conductive compound having a high consistency and a good coating property while having a high heat conductivity.

  Therefore, the inventors of the present invention provide a coarse metal powder having a specific particle size having a thermal conductivity of 200 W / m · K or more, a coarse inorganic filler having a specific particle size having a high hardness with a new Mohs hardness of 6 or more, and In combination, a fine inorganic filler with a specific particle size and a specific surface modifier are combined to make a heat conductive compound containing a specific amount of each, making the coarse metal powder difficult to crush and consistency. It was found that a thermally conductive compound having a high thermal conductivity and an excellent thermal conductivity can be obtained.

That is, the present invention comprises (A) a metal powder having a thermal conductivity of 200 W / m · K or more and an average particle size of 5 to 50 μm, and (B) a coarse inorganic material having a new Mohs hardness of 6 or more and an average particle size of 5 to 50 μm. 1 selected from a filler, (C) a fine inorganic filler having an average particle size of 0.15 to 2 μm, (D) a base oil, and (E) (poly) glyceryl ether, and an alkenyl succinimide and a boron derivative thereof. A high thermal conductivity compound containing at least a seed surface modifier, wherein the total content of (A), (B) and (C) is in the range of 88 to 97% by mass in the total amount of the compound, and (A ) And (B) and the mass ratio of the content of (C) is in the range of 20:80 to 85:15, the content of (D) is less than 12% by mass in the total amount of the compound, The content of (E) is 0.08 in the total amount of the compound. As the ratio is 4 wt% (A), provides a high thermal conductivity compound, wherein (B), (C), in which (D), and component (E) is blended Is.

In the high thermal conductivity compound, the present invention may further comprise (E) (poly) glyceryl ether, and one or more surface modifiers selected from alkenyl succinimide and its boron derivative in each of the total amount of the compound. The present invention provides a high thermal conductive compound containing 0.08 to 4% by mass.
Moreover, the present invention provides the high thermal conductive compound, wherein the metal powder (A) is an aluminum powder, the coarse inorganic filler (B) is a zinc oxide powder, the metal powder (A) and the coarse inorganic filler. The mass ratio of the content of (B) is in the range of 95: 5 to 5:95, and a highly thermally conductive compound in which the fine inorganic filler (C) is zinc oxide powder is provided.

The present invention also provides a high thermal conductivity compound, wherein the base oil is at least one selected from mineral oil, synthetic hydrocarbon oil, diester, polyol ester, and phenyl ether. is there.
Further, the present invention provides a high thermal conductivity compound in which the base oil contains one or more selected from diesters and polyol esters, and the content thereof is 2 to 90% by mass in the base oil. It is to provide.
The present invention also provides: (A) a metal powder having a thermal conductivity of 200 W / m · K or more and an average particle size of 5 to 50 μm; and (B) a coarse inorganic material having a new Mohs hardness of 6 or more and an average particle size of 5 to 50 μm. 1 selected from a filler, (C) a fine inorganic filler having an average particle size of 0.15 to 2 μm, (D) a base oil, and (E) (poly) glyceryl ether, and an alkenyl succinimide and a boron derivative thereof. The total content of (A), (B) and (C) is in the range of 88 to 97% by mass in the total amount of the compound, and the total content of (A) and (B). And the mass ratio of the content of (C) is in the range of 20:80 to 85:15, the content of (D) is less than 12% by mass in the total amount of the compound, and the content of (E) is the total amount of the compound It mix | blends so that it may become a ratio which is 0.08-4 mass% inside, respectively. The present invention provides a method for producing a high thermal conductivity compound.

  The high thermal conductivity compound of the present invention can exhibit better thermal conductivity without impairing the coating property. The high thermal conductivity compound of the present invention can improve the heat dissipation of electronic components that require heat countermeasures, and is particularly suitable as a heat dissipation material for CPUs and power semiconductors.

The inorganic filler used in the present invention is blended with a combination of a coarse inorganic filler and a fine inorganic filler for high filling.
The metal powder (A) has a thermal conductivity of 200 W / m · K or more and an average particle size of 5 to 50 μm. Examples of the metal powder having a thermal conductivity of 200 W / m · K or more include metal powders such as aluminum, copper, and silver, and aluminum powder is particularly preferable. 5-40 micrometers is preferable and, as for the average particle diameter of metal powder (A), 8-30 micrometers is especially preferable.

The coarse inorganic filler (B) is a coarse inorganic filler having a new Mohs hardness of 6 or more and an average particle diameter of 5 to 50 μm. When the coarse inorganic filler (B) is not included, or when the new Mohs hardness is lower than 6, the metal powder (A) is crushed during the roll mill treatment, and the consistency of the compound is lowered or the compound cannot be prepared. There is. The new Mohs hardness is preferably 7 or more, particularly preferably 7.5 or more. Examples of the coarse inorganic filler having a new Mohs hardness of 6 or more include powders such as zinc oxide, aluminum oxide, magnesium oxide, titanium oxide, aluminum nitride, silicon carbide, and silica. More preferably, a zinc oxide powder is mentioned. The average particle diameter of the coarse inorganic filler (B) is preferably 5 to 40 μm, more preferably 8 to 30 μm, and particularly preferably 8 to 25 μm. The maximum particle size of the coarse inorganic filler (B) is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less.

When the average particle size of the metal powder (A) and the coarse inorganic filler (B), that is, the coarse particles exceeds 50 μm, the coating film becomes thick and the thermal conductivity tends to be lowered. On the other hand, by setting the average particle size of the metal powder (A) and the coarse inorganic filler (B) to 5 μm or more, or by setting the average particle size of the fine inorganic filler (C) to 2 μm or less, the inorganic filling It becomes easy to close-pack the agent, and as a result, sufficient thermal conductivity is easily obtained.

The fine inorganic filler (C) is a fine inorganic filler having an average particle size of 0.15 to 2 μm. The average particle size of the fine inorganic filler (C) is preferably 0.2 to 1.8 μm, particularly preferably 0.3 to 1.5 μm. By setting the average particle size of the fine inorganic filler (C) to 0.15 μm or more, the total surface area of the inorganic filler can be kept moderate, so that the liquid components (base oil and surface modifier) The compound can be easily prepared, for example, it can be held sufficiently or can have an appropriate consistency. By setting the average particle size of the fine inorganic filler (C) to 2 μm or less, it becomes easy to close-pack the inorganic filler, and as a result, sufficient thermal conductivity is easily obtained. Examples of the fine inorganic filler (C) include powders of zinc oxide, aluminum oxide, boron nitride (hexagonal crystal) and the like. More preferably, a zinc oxide powder is mentioned.

Moreover, the mass ratio of the total content of the metal powder (A) and the coarse inorganic filler (B) and the fine inorganic filler (C) is in the range of 20:80 to 85:15, preferably Is in the range of 30:70 to 80:20, particularly preferably in the range of 35:65 to 70:30. When there are too many fine-grained inorganic fillers (C), the surface area of the inorganic fillers becomes too large and the liquid components (base oil and surface modifier) are insufficient, resulting in low consistency or inability to prepare compounds. There is. On the other hand, when there are too few fine inorganic fillers (C), it becomes impossible to close-pack with an inorganic filler, and as a result, oil separation may occur or sufficient thermal conductivity may not be obtained.

The content ratio of the metal powder (A) and the coarse inorganic filler (B) is preferably 95: 5 to 5:95, more preferably 90:10 to 5:95, and particularly preferably, by mass ratio. 85: 15-5: 95.

  The higher the filling rate of the inorganic filler, the better the thermal conductivity. In the present invention, the total content of (A), (B) and (C) is 88 to 97% by mass in the total amount of the compound, preferably Is 90-96 mass%. By setting it as 88 mass% or more, it becomes easy to obtain high thermal conductivity of 4.5 W / m · K or more, and it becomes easy to suppress oil separation or base oil oozing out. On the other hand, by setting it as 97 mass% or less, the fall of the consistency can be suppressed and a compound can be prepared easily.

Various base oils can be used as the base oil (D), and examples thereof include mineral oil, synthetic hydrocarbon oil, ester, polyether, phosphate ester, silicone oil, and fluorine oil. In terms of preventing separation of the base oil, silicone oil and fluorine oil having a low surface tension are less preferred. A base oil may be used individually by 1 type, or may be used in combination of 2 or more type.
Examples of the synthetic hydrocarbon oil include those obtained by polymerizing alpha olefins produced using ethylene, propylene, butene, and derivatives thereof as a raw material alone or in combination of two or more. Specific examples include polyalphaolefin (PAO) which is an oligomer of 1-decene, polybutene which is an oligomer of 1-butene and isobutylene, and a co-oligomer of ethylene and alphaolefin. Moreover, alkylbenzene, alkylnaphthalene, etc. can also be used.

Examples of esters include diesters and polyol esters.
Examples of the diester include esters of dibasic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid.
The polyol ester is an ester of neopentyl polyol having no hydrogen atom on the β-position carbon, and specifically includes carboxylic acid esters such as neopentyl glycol, trimethylolpropane, and pentaerythritol. Further, esters of aliphatic dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 2-butyl-2-ethylpropanediol, 2,4-diethyl-pentanediol and linear or branched saturated fatty acids are also used. be able to.

Examples of the polyether include polyglycol and phenyl ether.
Examples of the polyglycol include polyethylene glycol, polypropylene glycol, and derivatives thereof.
Examples of the phenyl ether include alkylated diphenyl ether represented by the following general formula (1).

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, (At least one of R ^{1 to} R ¹⁰ is a hydrocarbon group having 8 to 22 carbon atoms.)
Examples of phosphate esters include triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, and trixylenyl phosphate.
Since the high thermal conductivity compound is applied to the heat generating portion, it is exposed to a high temperature for a long time. For this reason, it is desirable that the base oil has excellent thermal oxidation stability.

The kinematic viscosity of the base oil is preferably 10mm ² / s~500mm ² / s at 40 ° ^C., particularly preferably 20mm ² / s~450mm 2 / s. If the viscosity is too low, evaporation or oil separation may occur at high temperatures. On the other hand, if the viscosity is too high, the consistency is lowered and the compound may be hardened.
Diesters and polyol esters can increase the consistency when used in combination with other base oil components. In that case, 1 type may be sufficient as the diester and polyol ester to combine, and 2 or more types may be combined. Further, the ratio of the diester or polyol ester is preferably 2 to 90% by mass, more preferably 2 to 50% by mass, and still more preferably 4 to 100% by mass of all base oil components including the diester or polyol ester. -30 mass%. By blending a diester or a polyol ester within the above range, a higher consistency can be achieved.

The content of the base oil is less than 12% by mass, preferably 2 to 12% by mass. When the content is more than this, the consistency becomes too high and the compound may flow out. In addition, oil separation may occur and thermal conductivity may decrease.
The surface modifier (E) used in the present invention improves the thermal conductivity by increasing the filling amount of the inorganic filler by adsorbing to the surface of the inorganic filler powder and improving the affinity with the base oil. It has the function of improving the coating properties by increasing the consistency. In addition, by using surface modifier (E), a coating film can be made still thinner and the heat conduction from a heat-emitting component to a heat radiating component can be performed efficiently.

Furthermore, the surface modifier (E) used in the present invention has high heat resistance as compared with substances conventionally used as surface modifiers. Therefore, it is possible to obtain a compound having good heat and oxidation stability of oil and high heat resistance.

As the type of the surface modifier, (poly) glyceryl ether, alkenyl succinimide and its boron derivative can be preferably used.
(Poly) glyceryl ether is a compound represented by the general formula (2).

（式中、Ｒ^１１は炭素数８以上の炭化水素基を表わし、ｐはグリセリンの重合度を表わす係数であって、１以上の数である。）
一般式（２）において、Ｒ^１１は炭素数８以上の炭化水素基を表わし、例えば、炭素数８以上のアルキル基、アルケニル基、アリール基が挙げられ、炭素数８以上のアルキル基、アルケニル基が好ましい。Ｒ^１１の炭素数は、８〜３０が好ましく、１０〜２６がより好ましく、１２〜２２が特に好ましい。また、一般式（２）において、ｐはグリセリンの重合度を表わす係数であって、１以上の数であり、好ましくは１〜５の数である。なお、ｐが１以上の場合は、ｐは平均値である。ｐが５を越えると基油への溶解性が悪くなる。

(In the formula, R ¹¹ represents a hydrocarbon group having 8 or more carbon atoms, and p is a coefficient representing the degree of polymerization of glycerin and is a number of 1 or more.)
In the general formula (2), R ¹¹ represents a hydrocarbon group having 8 or more carbon atoms, and examples thereof include an alkyl group, alkenyl group, and aryl group having 8 or more carbon atoms, and an alkyl group and alkenyl group having 8 or more carbon atoms. Is preferred. The number of carbon atoms in R ¹¹ is preferably 8 to 30, more preferably from 10 to 26, particularly preferably 12 to 22. Moreover, in General formula (2), p is a coefficient showing the polymerization degree of glycerol, is a number of 1 or more, preferably a number of 1-5. In addition, when p is 1 or more, p is an average value. If p exceeds 5, the solubility in the base oil will deteriorate.

The alkenyl succinimide and its boron derivative are compounds represented by the general formula (3).

(In the formula, R ¹² is an alkenyl group or polyalkenyl group having 1 to 50 carbon atoms, two R ¹² groups may be the same or different, and R ¹³ is an alkylene group having 2 to 5 carbon atoms, q is 1 to 10, and q + 1 R ¹³ may be the same or different.X is a boron-containing substituent.)
In the general formula (3), R ¹² is an alkenyl group or polyalkenyl group having 1 to 50 carbon atoms, and two R ¹² may be the same or different. Examples of the alkenyl group include a propenyl group, a butenyl group, and a pentenyl group. Examples of the polyalkenyl group include a polypropenyl group, a polybutenyl group, and a polypentenyl group. R ¹³ is an alkylene group having 2 to 5 carbon atoms. q is 1 to 10, and q + 1 R ¹³ may be the same or different. X is a boron-containing substituent, and examples of X include a group of the chemical formula (4).

At this time, the molecular weight of the polyalkenyl group is preferably about 70 to 50000, more preferably 200 to 5000, and particularly preferably 500 to 3000.
A surface modifier (E) may be used individually by 1 type, and may be used in combination of 2 or more type.
Further, the use of polyglyceryl ether, alkenyl succinimide and its boron derivative in combination can further increase the consistency. This combination can further increase the consistency by setting 95: 5 to 20:80, preferably 90:10 to 40:60, and more preferably 80:20 to 60:40.
The surface modifier (E) used in the present invention is preferably contained in an amount of 0.08 to 4.0% by mass in the total amount of the high thermal conductivity compound. More preferably, it is 0.1-2.0 mass%, Most preferably, it is 0.1-1.0 mass%, Most preferably, it is 0.1-0.5 mass%. An effect can be acquired because content of a surface modifier (E) shall be 0.08 mass% or more. On the other hand, even if the content is more than 4.0% by mass, the improvement of the effect corresponding to the addition amount cannot be obtained and it is not economical.

  Moreover, a well-known additive can be suitably mix | blended with the high heat conductive compound of this invention as needed. These include, for example, compounds such as phenols, amines and sulfur / phosphorus as antioxidants, and compounds such as sulfonates, carboxylic acids and carboxylates as corrosion inhibitors as rust inhibitors. Are compounds such as benzotriazole and derivatives thereof, and thiadiazole compounds, and examples of the thickener and thickener include polybutene, polymethacrylate, fatty acid salt, urea compound, petroleum wax, polyethylene wax and the like. The amount of these additives may be a normal amount.

Regarding the production of the high thermal conductivity compound of the present invention, the method is not limited as long as the components can be mixed uniformly. As a general production method, there is a method of kneading with a mortar, a planetary mixer, a twin-screw extruder, or the like to form a grease and then uniformly kneading with three rolls.
The immiscible penetration of the high thermal conductivity compound of the present invention can be used if it is approximately 200 or more. The immiscibility of the high thermal conductivity compound of the present invention is preferably 230 or more, more preferably 250 or more, and particularly preferably 280 or more.
The high thermal conductivity compound of the present invention can exhibit extremely excellent thermal conductivity, specifically, preferably can exhibit thermal conductivity of 4.5 W / m · K or more, and more preferably Can exhibit a thermal conductivity of 4.7 W / m · K or more, more preferably 5.0 W / m · K or more, and particularly preferably 5.3 W / m. -It can exhibit thermal conductivity of K or higher.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this.
Tables 1 to 3 show fillers, base oils and surface modifiers used in Examples and Comparative Examples.

※表中における酸化亜鉛の新モース硬度＝８

* New Mohs hardness of zinc oxide in the table = 8

表中、Ｐｈｅ１は、一般式（１）のＲ^１〜Ｒ^１０のうち、１つ又は２つが炭素数^１２と炭素数^１４の直鎖又は分岐鎖アルキル基のものを示す。

In the table, Phe1 represents a linear or branched alkyl group having ¹² or ¹⁴ carbon atoms, one or two of R ^{1 to} R ^{10 in} the general formula (1).

(Examples 1-8)
Table 4 below shows the compositions of Examples 1 to 8. In addition, other * in the table indicates an amine-based antioxidant.
Each component was mix | blended so that it might become a composition of Table 4, and the heat conductive compound was prepared with the following method.
Production method: Various additives such as surface modifiers and antioxidants were dissolved in the base oil, and placed in a planetary mixer or automatic mortar together with an inorganic filler. The mixture was kneaded at room temperature to 60 ° C. for 60 minutes and mixed well to obtain a grease. Thereafter, kneading with a three roll was carried out twice to prepare a heat conductive compound.

The performance shown below was evaluated using the obtained heat conductive compound.
Consistency: An immiscible consistency was measured in accordance with JIS-K2220. The greater the consistency value, the softer the compound, and vice versa.
Oil separation: measured in accordance with JIS-K2220.
Thermal conductivity: measured at 0 ° C. by a hot wire method.

表中、その他※：アミン系酸化防止剤
（比較例１〜８）
下記表５の組成になるように各成分を配合して、熱伝導性コンパウンドを実施例と同様の方法で調製した。

In the table, other *: Amine-based antioxidant (Comparative Examples 1 to 8)
Each component was mix | blended so that it might become a composition of following Table 5, and the heat conductive compound was prepared by the method similar to an Example.

表中、その他※：アミン系酸化防止剤
表６に実施例１〜８と比較例１〜８の不混和ちょう度、熱伝導率、離油度を示す。

In the table, other *: amine-based antioxidant Table 6 shows the immiscible penetration, thermal conductivity, and oil separation degree of Examples 1-8 and Comparative Examples 1-8.

As can be seen from Table 6, in Examples 1 to 8, even if the filler is highly filled to increase the thermal conductivity, the consistency is high and the coating property is excellent, and the occurrence of oil separation is not observed.
On the other hand, in Comparative Examples 1 and 2 in which the metal powder (A) is not used, the thermal conductivity is lower than that in the present example. In Comparative Example 3 excluding the coarse inorganic filler (B), the particles of the metal powder (A) are crushed during the production process and do not become grease. If the surface modifier is too little, the compound will be hard or not greased (Comparative Example 4). In Comparative Example 5 where the amount of the inorganic filler is small, a high consistency is obtained, but the thermal conductivity is lowered. In Comparative Examples 6 to 8 using a silane-based surface modifier or a nonionic surfactant, the grease does not become a grease when the consistency is low or the filling rate is increased.

Moreover, about the heat conductive compound of Example 6, the film thickness of the thin film was measured with the following thin film measurement method. The film thickness was 74 μm.
<Thin film measurement method>
A heat conductive compound of 0.05 ml was sandwiched between two aluminum plates with a surface roughness Ra = 0.5 μm and crushed by applying a load of 3 kg, and the spreading area after 300 seconds was measured to calculate the film thickness. .

Claims (5)

(A) a metal powder having a thermal conductivity of 200 W / m · K or more and an average particle size of 5 to 50 μm,
(B) a coarse inorganic filler having a new Mohs hardness of 6 or more and an average particle size of 5 to 50 μm,
(C) a fine inorganic filler having an average particle size of 0.15 to 2 μm,
(D) a base oil, and (E) (poly) glyceryl ether, and a high thermal conductivity compound containing one or more surface modifiers selected from alkenyl succinimide and boron derivatives thereof,
The total content of (A), (B) and (C) is in the range of 88 to 97% by mass in the total amount of the compound, and the total content of (A) and (B) and the mass of the content of (C) The ratio is in the range of 20:80 to 85:15, the content of (D) is less than 12% by mass in the total amount of the compound, and the content of (E) is 0.08 to 4% by mass in the total amount of the compound, respectively. (A), (B), (C), (D), and (E) component are mix | blended so that it may become a ratio which is these, The high heat conductive compound characterized by the above-mentioned. The metal powder (A) is an aluminum powder, the coarse inorganic filler (B) is a zinc oxide powder, and the mass ratio of the content of the metal powder (A) and the coarse inorganic filler (B) is 95: 5. The high thermal conductivity compound according to claim 1, wherein the fine inorganic filler (C) is zinc oxide powder in a range of -5: 95. The high thermal conductivity compound according to claim 1 or 2, wherein the base oil is at least one selected from mineral oil, synthetic hydrocarbon oil, diester, polyol ester, and phenyl ether. The base oil contains 1 or more types chosen from diester and a polyol ester, The content is 2-90 mass% in base oil, The high heat conductive compound in any one of Claims 1-3. (A) a metal powder having a thermal conductivity of 200 W / m · K or more and an average particle size of 5 to 50 μm,
(B) a coarse inorganic filler having a new Mohs hardness of 6 or more and an average particle size of 5 to 50 μm,
(C) a fine inorganic filler having an average particle size of 0.15 to 2 μm,
(D) base oil, and
(E) (poly) glyceryl ether, and one or more surface modifiers selected from alkenyl succinimides and boron derivatives thereof,
The total content of (A), (B) and (C) is in the range of 88 to 97% by mass in the total amount of the compound, and the total content of (A) and (B) and the mass of the content of (C) The ratio is in the range of 20:80 to 85:15, the content of (D) is less than 12% by mass in the total amount of the compound, and the content of (E) is 0.08 to 4% by mass in the total amount of the compound, respectively. The manufacturing method of the high heat conductive compound characterized by mix | blending so that it may become a ratio.