Thick film element with high heat conductivity on two sides thereof

Abstract

The present invention provides a thick film element with high heat conductivity on two sides thereof, which comprises a carrier, a thick film coating deposited on the carrier, and a covering layer overlays on the coating; the thick film coating is heating materials, and mode of heating is electrical heating, wherein the carrier, the thick film coating and the covering layer are selected from the material that fulfill every following equations: Q.sub.2Q.sub.3; Q.sub.2Q.sub.1; and Q.sub.1=aQ.sub.3, Q.sub.2=bQ.sub.1, Q.sub.2=cQ.sub.3; and 0.1a150, 1b2500, 100c10000. The thick film element of the present invention has high heat conductivity and uniform heat generating rate on both sides thereof, thus improving heat transfer efficiency of the product; it could be applied in products that require double-sided high heat conductivity, meeting the market demand for multifunctional heating products.

Claims

1. A thick film element with high heat conductivity on two sides thereof, comprising: a carrier; a thick film coating deposited on the carrier; and a covering layer overlaid on the coating, wherein the thick film coating is a heating material, and a mode of heating is electrical heating, wherein the carrier, the thick film coating and the covering layer are selected from a material that fulfills every of following equations:
Q.sub.2Q.sub.3;
Q.sub.2Q.sub.1;
and Q.sub.1=aQ.sub.3, Q.sub.2=bQ.sub.1, Q.sub.2=cQ.sub.3;
wherein 0.1a150, 1b2500, 100c10000: wherein a calculation formula for Q.sub.1 is $Q_1={}_{1}A\frac{T_1-T_0}{b_1},$ a calculation formula for Q.sub.2 is $Q_2={}_{2}A\frac{T_2-T_0}{b_2},$ a calculation formula for Q.sub.3 is $Q_3={}_{3}A\frac{T_3-T_0}{b_3},$
T.sub.2<T.sub.Minimum melting point of the covering layer;
T.sub.2<T.sub.Minimum melting point of the carrier,
T.sub.025 C.; wherein Q.sub.1 represents a heat transfer rate of the covering layer; Q.sub.2 represents a heat transfer rate of the thick film coating; Q.sub.3 represents a heat transfer rate of the carrier; .sub.1 represents a heat conductivity coefficient of the covering layer; .sub.2 represents a heat conductivity coefficient of the thick film coating; .sub.3 represents a heat conductivity coefficient of the carrier; A represents a contact area of the thick film coating with the covering layer or the carrier; b.sub.1 represents a thickness of the covering layer; b.sub.2 represents a thickness of the thick film coating; b.sub.3 represents a thickness of the carrier; T.sub.0 represents an initial temperature of the thick film element; T.sub.1 represents a surface temperature of the covering layer; T.sub.2 represents a heating temperature of the thick film coating; T.sub.3 represents a surface temperature of the carrier; b.sub.250 m; b.sub.3b.sub.1, b.sub.11 mm, b.sub.31 mm; and T.sub.Minimum melting point of carrier>25 C.

2. The thick film element according to claim 1, wherein the carrier and the thick film coating are bound by printing or sintering, the thick film coating and the covering layer are bound by printing or sintering.

3. The thick film element according to claim 2, wherein an area between the carrier and the covering layer without the thick film coating is bound by printing or sintering.

4. The thick film element according to claim 1, wherein the carrier comprises polyimides, organic insulating materials, inorganic insulating materials, ceramics, glass ceramics, quartz, crystal and stone materials.

5. The thick film element according to claim 1, wherein the thick film coating is one or more of silver, platinum, palladium, palladium oxide, gold and rare earth materials.

6. The thick film element according to claim 1, wherein the covering layer is made from one or more of polyester, polyimide or polyetherimide (PEI), ceramics, silica gel, asbestos, and micarex.

7. The thick film element according to claim 1, wherein an area of the thick film coating is smaller than or equal to an area of the covering layer or an area of the carrier.

8. A use of a thick film element for products with double-sided heating, wherein the thick film element with high heat conductivity on two sides thereof, comprising: a carrier; a thick film coating deposited on the carrier; and a covering layer overlaid on the coating, wherein the thick film coating is a heating material, and a mode of heating is electrical heating, wherein the carrier, the thick film coating and the covering layer are selected from a material that fulfills every of following equations:
Q.sub.2Q.sub.3;
Q.sub.2Q.sub.1;
and Q.sub.1=aQ.sub.3, Q.sub.2=bQ.sub.1, Q.sub.2=cQ.sub.3;
wherein 0.1a150, 1b2500, 100c10000; wherein a calculation formula for Q.sub.1 is $Q_1={}_{1}A\frac{T_1-T_0}{b_1},$ a calculation formula for Q.sub.2 is $Q_2={}_{2}A\frac{T_2-T_0}{b_2},$ a calculation formula for Q.sub.3 is $Q_3={}_{3}A\frac{T_3-T_0}{b_3},$
T.sub.2<T.sub.Minimum melting point of the covering layer;
T.sub.2<T.sub.Minimum melting point of the carrier;
T.sub.025 C.; wherein Q.sub.1 represents a heat transfer rate of the covering layer; Q.sub.2 represents a heat transfer rate of the thick film coating; Q.sub.3 represents a heat transfer rate of the carrier; .sub.1 represents a heat conductivity coefficient of the covering layer; .sub.2 represents a heat conductivity coefficient of the thick film coating; .sub.3 represents a heat conductivity coefficient of the carrier; A represents a contact area of the thick film coating with the covering layer or the carrier; b.sub.1 represents a thickness of the covering layer; b.sub.2 represents a thickness of the thick film coating; b.sub.3 represents a thickness of the carrier; To represents an initial temperature of the thick film element; T.sub.1 represents a surface temperature of the covering layer; T.sub.2 represents a heating temperature of the thick film coating; T.sub.3 represents a surface temperature of the carrier; b.sub.250 m; b.sub.3b.sub.1, b.sub.11 mm, b.sub.31 mm; and T.sub.minimum melting point of the carrier>25 C.

9. The thick film element according to claim 8, wherein the carrier and the thick film coating are bound by printing or sintering, the thick film coating and the covering layer are bound by printing or sintering.

10. The thick film element according to claim 9, wherein an area between the carrier and the covering layer without the thick film coating is bound by printing or sintering.

11. The thick film element according to claim 8, wherein the carrier comprises polyimides, organic insulating materials, inorganic insulating materials, ceramics, glass ceramics, quartz, crystal and stone materials.

12. The thick film element according to claim 8, wherein the thick film coating is one or more of silver, platinum, palladium, palladium oxide, gold and rare earth materials.

13. The thick film element according to claim 8, wherein the covering layer is made from one or more of polyester, polyimide or polyetherimide (PEI), ceramics, silica gel, asbestos, and micarex.

14. The thick film element according to claim 8, wherein an area of the thick film coating is smaller than or equal to an area of the covering layer or an area of the carrier.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

(2) The present invention discloses a thick film element with high heat conductivity on two sides thereof of the present invention, comprises a carrier, a thick film coating deposited on the carrier, and a covering layer overlaid on the coating. The thick film coating is a heating material, and the mode of heating is electrical heating. The carrier, the thick film coating and the covering layer are selected from a material that fulfills every of the following equations:
Q.sub.2Q.sub.3;
Q.sub.2Q.sub.1;
and Q.sub.1=aQ.sub.3, Q.sub.2=bQ.sub.1, Q.sub.2=cQ.sub.3;
and 0.1a150, 1b2500, 100c10000;
wherein, the calculation formula for Q.sub.1:

(3) $Q_1={}_{1}A\frac{T_1-T_0}{b_1},$
the calculation formula for Q.sub.2:

(4) $Q_2={}_{2}A\frac{T_2-T_0}{b_2},$
the calculation formula for Q.sub.3:

(5) $Q_3={}_{3}A\frac{T_3-T_0}{b_3},$
T.sub.2<T.sub.Minimum melting point of the covering layer;
T.sub.2<T.sub.Minimum melting point of the carrier;
T.sub.025 C.;
b.sub.2 represents the thickness of the thick film coating, b.sub.250 m;
b.sub.1 represents the thickness of the covering layer; b.sub.3 represents the thickness of the carrier, b.sub.3b.sub.1, b.sub.11 mm, b.sub.31 mm;
T.sub.Minimum melting point of the carrier>25 C.

(6) The following embodiments include 20 thick film elements prepared by the inventors, and the materials for preparing the covering layer, the thick film coating and the carrier of the 20 listed thick film elements all satisfy the above equations above. The detailed preparing method and formula are provided as follows:

Embodiments

(7) Silver paste with a heat conductivity coefficient of .sub.2 is selected to prepare the thick film coating, polyimides with a heat conductivity coefficient of .sub.3 is selected to prepare the carrier, and polyimides with a heat conductivity coefficient of .sub.1 is selected to prepare the covering layer. The three layers are bound by sintering. The area of the prepared thick film coating is A.sub.2, the thickness is b.sub.2; the area of the covering layer is A.sub.1, the thickness is b.sub.1; the area of the carrier is A.sub.3, the thickness is b.sub.3.

(8) Turn on an external DC power supply to charge the thick film coating. The thick film starts to heat up; when the heating is stabled, measure the surface temperature of the covering layer and the carrier, and the heating temperature of the thick film coating under a stable heating state is measured. Heat transfer rate of the covering layer and the carrier, and heat generating rate of the thick film coating are calculated according to the following formula:

(9) 0$Q_1={}_{1}A\frac{T_1-T_0}{b_1},Q_2={}_{2}A\frac{T_2-T_0}{b_2},Q_3={}_{3}A\frac{T_3-T_0}{b_3}.$

(10) Tables 1 to 4 are the 20 thick film elements prepared by the inventors. After provided electricity to heat for 2 minutes, the thick film elements are measured according to the national standards to obtain the performance data (heat conductivity coefficient, surface temperature) as shown in the Tables. The thickness, contact area, initial temperature are measured before heating.

(11) Table 1 is the performance data of the covering layers of the thick film elements in Embodiments 1 to 20. The details are as follows:

(12) TABLE-US-00001 TABLE 1 Covering Layer Heat Conductivity Surface Initial Coefficient .sub.1 Thickness Temperature T.sub.Minimum melting point of the covering layer Temperature (W/m .Math. k) b.sub.1 (m) T.sub.1 ( C.) ( C.) T.sub.0 ( C.) Embodiment 1 7.2 25 113 350 25 Embodiment 2 7.2 25 55 350 25 Embodiment 3 7.2 25 102 350 25 Embodiment 4 7.2 50 53 350 25 Embodiment 5 7.2 50 97 350 25 Embodiment 6 7.2 75 51 350 25 Embodiment 7 7.2 75 94 350 25 Embodiment 8 7.2 75 47 350 25 Embodiment 9 7.2 100 93 350 25 Embodiment 10 7.2 100 44 350 25 Embodiment 11 7.2 200 48 350 25 Embodiment 12 7.2 200 93 350 25 Embodiment 13 7.2 300 91 350 25 Embodiment 14 7.2 300 44 350 25 Embodiment 15 7.2 400 96 350 25 Embodiment 16 7.2 400 44 350 25 Embodiment 17 7.2 500 101 350 25 Embodiment 18 7.2 500 47 350 25 Embodiment 19 7.2 600 92 350 25 Embodiment 20 7.2 600 30 350 25

(13) Table 2 is the performance data of the thick film coatings of the thick film elements in Embodiments 1 to 20. The details are as follows:

(14) TABLE-US-00002 TABLE 2 Thick Film Coating Heat Conductivity Heating Initial Coefficient .sub.2 Thickness Area A.sub.2 temperature T.sub.2 temperature (W/m .Math. k) b.sub.2 (m) (m.sup.2) ( C.) T.sub.0 ( C.) Embodiment 1 382 50 0.016 116 25 Embodiment 2 382 50 0.056 56 25 Embodiment 3 382 40 0.016 103 25 Embodiment 4 382 40 0.056 54 25 Embodiment 5 382 30 0.016 98 25 Embodiment 6 382 30 0.056 52 25 Embodiment 7 382 30 0.016 95 25 Embodiment 8 382 25 0.056 51 25 Embodiment 9 382 25 0.016 97 25 Embodiment 10 382 25 0.056 46 25 Embodiment 11 382 30 0.016 49 25 Embodiment 12 382 30 0.056 95 25 Embodiment 13 382 20 0.016 95 25 Embodiment 14 382 20 0.056 45 25 Embodiment 15 382 30 0.016 99 25 Embodiment 16 382 30 0.056 46 25 Embodiment 17 382 35 0.016 103 25 Embodiment 18 382 35 0.056 49 25 Embodiment 19 382 25 0.016 94 25 Embodiment 20 382 25 0.056 36 25

(15) Table 3 is the performance data of the carriers of the thick film elements in Embodiments 1 to 20. The details are as follows:

(16) TABLE-US-00003 TABLE 3 Carrier Heat Conductivity Surface Initial Coefficient .sub.3 Thickness b.sub.3 Temperature T.sub.Minimum melting point of the carrier Temperature (W/m .Math. k) (m) T.sub.3 ( C.) ( C.) T.sub.0 ( C.) Embodiment 1 7.2 1 105 350 25 Embodiment2 7.2 2 42 350 25 Embodiment 3 7.2 3 87 350 25 Embodiment4 7.2 1 43 350 25 Embodiment 5 7.2 2 86 350 25 Embodiment 6 7.2 1 40 350 25 Embodiment 7 7.2 2 84 350 25 Embodiment 8 7.2 3 38 350 25 Embodiment 9 7.2 1 87 350 25 Embodiment 10 7.2 2 40 350 25 Embodiment 11 7.2 3 38 350 25 Embodiment 12 7.2 4 78 350 25 Embodiment 13 7.2 1 85 350 25 Embodiment 14 7.2 2 39 350 25 Embodiment 15 7.2 3 85 350 25 Embodiment 16 7.2 4 34 350 25 Embodiment 17 7.2 3 87 350 25 Embodiment 18 7.2 4 31 350 25 Embodiment 19 7.2 1 91 350 25 Embodiment 20 7.2 2 36 350 25

(17) Table 4 is the heat transfer rate calculated according to the performance data listed in Tables 1, 2 and 3. The heat transfer rates of the covering layer, the thick film coating and the carrier are calculated by ratio to obtain the limiting conditions of the materials of the present invention, namely the following equations:
Q.sub.2Q.sub.3; Q.sub.2Q.sub.1; and Q.sub.1=aQ.sub.3, Q.sub.2=bQ.sub.1, Q.sub.2=cQ.sub.3; wherein 0.1a150, 1b2500, 100c10000.

(18) TABLE-US-00004 TABLE 4 Covering Thick Film Layer Coating Carrier Heat Transfer Heat Generating Heat Transfer Satisfy the Rate Q.sub.1 Rate Q.sub.2 Rate Q.sub.3 Q.sub.2/Q.sub.1 Q.sub.2/Q.sub.3 Q.sub.1/Q.sub.3 equations? Embodiment 1 419328 11123840 10483.2 26.5278 1061 40 Yes Embodiment 2 467712 13263040 5846.4 28.3573 2269 80 Yes Embodiment 3 359424 11918400 2995.2 33.1597 3979 120 Yes Embodiment 4 217728 16044000 10886.4 73.6883 1474 20 Yes Embodiment 5 163584 14872533 4089.6 90.9168 3637 40 Yes Embodiment 6 145152 19252800 10886.4 132.639 1769 13.333 Yes Embodiment 7 107520 1421333.3 4032 13.2192 352.5 26.667 Yes Embodiment 8 96768 22247680 2419.2 229.907 9196 40 Yes Embodiment 9 82944 17602560 8294.4 212.222 2122 10 Yes Embodiment 10 84672 17969280 4233.6 212.222 4244 20 Yes Embodiment 11 13824 4889600 921.6 353.704 5306 15 Yes Embodiment 12 141120 49914667 7056 353.704 7074 20 Yes Embodiment 13 26880 21392000 8064 795.833 2653 3.3333 Yes Embodiment 14 26880 21392000 4032 795.833 5306 6.6667 Yes Embodiment 15 21312 15076267 2841.6 707.407 5306 7.5 Yes Embodiment 16 17136 14974400 1713.6 873.856 8739 10 Yes Embodiment 17 17971.2 13621029 2995.2 757.937 4548 6 Yes Embodiment 18 19353.6 14668800 2419.2 757.937 6063 8 Yes Embodiment 19 13248 16869120 7948.8 1273.33 2122 1.6667 Yes Embodiment 20 4032 9412480 4435.2 2334.44 2122 0.9091 Yes
The results listed in Table 4 shows that the thick films prepared according to Embodiments 1 to 20 all satisfy the equations; both sides of the thick film generate heat evenly, and the temperature difference between the two sides is smaller than 16 C. The thick film element could rise to more than 100 C. after given electricity for 2 minutes, demonstrating that thick film element of the present invention has high heat generating efficiency.

(19) Tables 5 to 8 are the performance data of the thick film elements in Contrasting Examples 1 to 3 of the present invention. All the performance data is measured as those shown in Tables 1 to 4. The details are as follows:

(20) TABLE-US-00005 TABLE 5 Covering Layer Heat Conductivity Surface Initial Coefficient .sub.1 Thickness Temperature T.sub.Minimum melting point of the covering layer Temperature T.sub.0 (W/m .Math. k) b.sub.1 (m) T.sub.1 ( C.) ( C.) ( C.) Contrasting 7.2 25 102 350 25 Example 1 Contrasting 7.2 50 97 350 25 Example 2 Contrasting 7.2 75 94 350 25 Example 3

(21) TABLE-US-00006 TABLE 6 Thick Film Coating Heat Conductivity Heating Initial Coefficient .sub.2 Thickness b.sub.2 Area A.sub.2 Temperature T.sub.2 Temperature (W/m .Math. k) (m) (m.sup.2) ( C.) T.sub.0 ( C.) Contrasting 382 40 0.016 103 25 Example 1 Contrasting 382 30 0.016 96 25 Example 2 Contrasting 382 30 0.016 95 25 Example 3

(22) TABLE-US-00007 TABLE 7 Carrier Heat Conductivity Surface Initial Coefficient .sub.3 Thickness b.sub.3 Temperature T.sub.3 T.sub.Minimum melting point of the carrier Temperature T.sub.0 (W/m .Math. k) (m) ( C.) ( C.) ( C.) Contrasting 7.2 3 56 350 25 Example 1 Contrasting 2.7 2 55 350 25 Example 2 Contrasting 3.5 2 48 350 25 Example 3

(23) TABLE-US-00008 TABLE 8 Satisfy the Q.sub.1 Q.sub.2 Q.sub.3 Q.sub.2/Q.sub.1 Q.sub.2/Q.sub.3 Q.sub.1/Q.sub.3 equations? Contrasting 359424 11918400 1190.4 33.1 10012.09 301 No Example 1 Contrasting 163584 14872533 648 90.9 22951.44 252 No Example 2 Contrasting 107520 1421333.3 644 13 2207.03 166 No Example 3

(24) Material and structure of the thick film elements in the Contrasting Examples 1 to 3 listed in the above tables neither meet the material selection requirement of the present invention nor satisfy the equations of the present invention. After given electricity and heat generation, both sides of the thick film could not generate heat evenly, and the temperature difference between the two sides is more than 40 C. It is the result of overly fast temperature rising of the covering layer and overly slow temperature rising of the carrier, which do not meet the requirement of the thick film element with high heat conductivity on both sides thereof of the present invention or meet the product requirement of the present invention, which demonstrates the heat transfer rate and correlation of the present invention

(25) According to the disclosure and teaching of above-mentioned specification, those skilled in the art of the present invention can still make changes and modifications to above-mentioned embodiment, therefore, the scope of the present invention is not limited to the specific embodiments disclosed and described above, and all those modifications and changes to the present invention are within the scope of the present invention as defined in the appended claims. Besides, although some specific terminologies are used in the specification, it is merely as a clarifying example and shall not be constructed as limiting the scope of the present invention in any way.