TW201347621A - Copper-based circuit board - Google Patents

Abstract

Provided is a copper-based circuit board, which is capable of suppressing peeling of an insulating layer after a laminate is formed, even if the laminate is formed using a highly heat-resistant resin for a copper substrate for the applications, such as power modules, where high heat dissipation is required. A copper-based circuit board (1) having a wiring pattern (7) formed on one side surface (3a) of a copper substrate (3) with an insulating layer (5) therebetween is characterized in that: the insulating layer (5) is formed of a resin having a laminate-forming temperature of 260-400 DEG C, at which a laminate is formed with the copper substrate (3); the copper substrate (3) is formed of a Cu-based alloy wherein a change of hardness is suppressed to a higher temperature compared with a copper substrate using pure copper; and the hardness can be maintained even if the insulating layer (5) and the copper substrate (3) are laminated at a temperature of 260-400 DEG C, thereby maintaining flatness even in press-blanking and the like after the laminate is formed, improving assemblability of a heat sink and the like, and furthermore, maintaining durability even when used for the applications, such as power modules, under high temperature environment.

Description

Copper-based circuit board

The present invention relates to a copper-based circuit substrate for a power module or the like.

As is known, a metal-based circuit board in which a wiring pattern is formed on one side of a metal substrate via an insulating layer is known. When the metal substrate is used for LED lighting or the like, aluminum or an aluminum alloy is used in consideration of heat dissipation.

On the other hand, in applications for power modules and the like, it is preferable to use a copper substrate having a higher thermal conductivity because of the requirement for higher heat dissipation, and the resin used for the insulating layer is required to have higher heat resistance. .

On the other hand, when a high heat resistant resin is used, it is also required to be laminated on a copper substrate at a temperature higher than 260 ° C, and the copper substrate using pure copper is annealed and softened, which has a problem of reduced machinability.

Therefore, when a copper-based circuit board formed in an aggregate form is punched and punched to form a single body, the copper substrate is deformed during press punching and drilling, and flatness cannot be maintained, and a heat sink or the like cannot be maintained. The assembly is reduced, and as a power module or the like, use in a high temperature environment causes early damage and reduces durability.

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 8-4109

The problem to be solved is that when an insulating layer is formed by using a high heat resistant resin laminated layer on a copper substrate for use in a power supply module or the like, the flatness is not maintained, the assemblability is lowered, and the power module is used. When used in a high temperature environment, it will cause early damage and reduce durability.

Even if it is used for a high-heat-resistance application such as a power supply module, and the insulating layer is formed of a high heat-resistant resin layer on the copper substrate, the flatness can be maintained and the durability at the time of use can be maintained. Therefore, it is one of the copper substrates. A copper-based circuit board having a wiring pattern formed on an insulating layer on the side thereof, wherein the insulating layer is formed of a high heat-resistant resin, and the copper substrate is suppressed in hardness by a temperature higher than that of a copper substrate using pure copper. It is formed by a copper alloy of the main body; even if the insulating layer is formed on the side of one side of the copper substrate at a temperature higher than the temperature at which the pure copper starts to be annealed, it can be maintained on the copper substrate using pure copper to form a laminate, and the machinability and substrate plane The high performance related to the deviation of degree and flatness can also maintain high temperature durability.

Since the copper-based circuit board of the present invention has the above-described configuration, even if an insulating layer and a copper substrate of a high heat-resistant resin are laminated at a heating temperature of, for example, 260 to 400 ° C, the temperature at which the pure copper starts to be annealed is compared with the copper substrate using pure copper. The above can also suppress the change in the hardness, and the flatness can be maintained in the subsequent punching and punching processing, and the assembly property of the heat sink (heat dissipation structure) can be improved, and even as a power supply module or the like. It can be used in high temperature environments to maintain durability.

1, 1A, 1B, 1C‧‧‧ copper-based circuit board

1a‧‧‧Pressing and cutting department

3‧‧‧ copper substrate

3a‧‧‧ side

3b‧‧‧Other side

5, 17‧‧‧ insulation

7, 15, 19‧‧‧ wiring patterns

8‧‧‧ hole

9‧‧‧Next layer

10‧‧ ‧ fixing

11‧‧‧Substrate

13‧‧‧glass cloth epoxy layer

1 is a cross-sectional view (cross-sectional view) of a copper-based circuit board (Example 1); FIG. 2 is a graph showing a comparison of composition and characteristics of a copper substrate (Example 1); and FIG. 3 shows a pair of pure copper and various Graph of hardness change caused by heat history of a substrate formed of a copper alloy (Examples 1 to 3); Fig. 4 is a graph showing a composition of a copper substrate (Example 1); and Fig. 5 is a copper for performing hole processing Rear view of the base circuit substrate sample (Embodiment 1); Fig. 6 is a side view (side view) showing the flatness test condition of the copper-based circuit substrate sample (Embodiment 1); Fig. 7 shows a copper-based circuit substrate A cross-sectional view of a principal part of the indentation of the sample (Embodiment 1); a cross-sectional view of a copper-based circuit substrate (Embodiment 1); and a cross-sectional view of a Cu-based circuit substrate (Embodiment 1) And Fig. 10 is a cross-sectional view of a copper-based circuit substrate (Embodiment 1).

"The use of a high-heat-resistance resin layer to form an insulating layer on a copper substrate for use in a power supply module or the like, and the maintenance of flatness and the maintenance of heat resistance under use can be achieved by the purpose of "The insulating layer 5 is formed of a resin having a temperature of 260 to 400 ° C when laminated with the copper substrate 3, and the copper substrate 3 is a copper alloy having a temperature higher than that of a pure copper substrate. Even if the insulating layer 5 is formed on the side surface 3a of the copper substrate 3 at a temperature higher than the temperature at which the pure copper starts to be annealed, it can be maintained on the copper substrate using pure copper to form a laminate, machinability, substrate flatness, The high performance related to the deviation of the flatness can also be achieved by maintaining high temperature durability.

Fig. 1 is a cross-sectional view showing a copper-based circuit board.

As shown in FIG. 1, the copper-based circuit board 1 is formed with a copper foil wiring pattern 7 via an insulating layer 5 on one side surface 3a of a copper substrate 3 made of a copper alloy or the like. The copper-based circuit board 1 is manufactured as a plurality of integrally formed aggregates, and each of the copper-based circuit boards 1 is separated by press working.

The copper-based circuit board 1 is filled with an insulating resin from one side surface 3a to the press-cut portion 1a in a casing (not shown) and is resin-sealed. Further, although not shown, a circuit component is attached to a predetermined portion of the wiring pattern 7, and is simultaneously encapsulated in an insulating resin by a resin.

The thickness of the copper substrate 3 of the copper-based circuit board 1 is set to 0.5 mm or more and 10 mm or less, and the thickness of the insulating layer 5 is set to 10 to 200 μm.

The insulating layer 5 is formed of a resin having a molding temperature of 260 to 400 ° C (for example, a composition in which an insulating inorganic filler is dispersed in a polyamidoximine resin). In the second drawing, the type of the resin used in each example is exemplified in the lowermost row. PAI means a polyamidoximine resin, and LCP means a liquid crystal polymer resin. The copper substrate 3 is formed by a copper alloy mainly composed of Cu which is higher in hardness change than a copper substrate using pure copper, and is formed, for example, of a copper alloy containing Fe or P.

The insulating layer 5 is made of a polyamidoximine resin, a liquid crystal polymer, a polyamidene resin (polyimine resin), a cyanate resin, and a polyphenylene sulfide resin as a resin having a molding temperature of 260 to 400 ° C. , polyether oxime resin, fluorine resin, polydiether ketone resin (polyether ether ketone resin), polyethylene terephthalate resin, polybutylene terephthalate resin, can be formed A composition in which an insulating inorganic filler having a thermal conductivity of 20 W/mK or more is dispersed is used.

In order to achieve high heat dissipation and high heat resistance, in the first embodiment, the copper substrate 3 is made of 97.0% by weight or more. Less than 100% by weight of Cu is mainly composed of a copper alloy containing Fe and P. Further, the metal to be contained may be other than Fe or P, and the content thereof may be changed as needed.

Fig. 2 is a graph showing a comparison of the composition and characteristics of a copper substrate; Fig. 3 is a graph showing a change in hardness due to a heat history of a substrate formed of pure copper and various copper alloys; and Fig. 4 is a view showing a copper substrate. Figure 5 is a rear view of a copper-based circuit substrate sample for performing hole processing; Figure 6 is a side view showing a flatness test condition of a copper-based circuit substrate sample; and Figure 7 is a copper-based circuit substrate sample. The main part of the indentation is an enlarged sectional view.

As shown in Fig. 2, in the first embodiment, for example, as the composition of the copper substrate 3, the embodiment 1-a: C19210-O, and the embodiment 1-b: C19210-1/2H (the CDA alloy) are used. Number - trait naming table). All of them use a copper alloy having a copper content of 99.81 to 99.925 wt% and containing 0.05 to 0.15 wt% of Fe and 0.025 to 0.04 wt% of P. Further, the second and third embodiments of Fig. 2 are described later.

The copper substrates of Comparative Examples 1 and 2 were pure copper in which Cu was 99.95 wt% or more and O was 0.0010 wt% or less.

The data item is provided with substrate thickness, hardness (initial value), heat treatment conditions, hardness (after heat treatment), flatness after processing, flatness deviation, indentation of processed product, 260 ° C (reference reflow oven temperature) The specification value of hardness, high temperature durability, and hardness after heating for 2 hr.

The thickness of the base material is the thickness of the copper substrate 3, the hardness (initial value) is the hardness before the heat treatment, and the heat treatment conditions are the conditions when the copper substrate 3 is heated and laminated to form the insulating layer 5.

The hardness after heating is the Vickers hardness after forming the copper clad laminate by heating, and the flatness is the flatness of one side surface 3a and the other side surface 3b of the copper substrate 3. The flatness deviation is a deviation of the flatness of the plurality of copper-clad laminates sampled. The indentation property is caused by the press-fitting of the press-cut portion 1a after the punching and cutting, such as a punching process, or the occurrence of the depression of the hole edge portion formed by the drilling process. The hardness after heating at 260 ° C is the hardness after heat treatment based on the temperature of the reflow furnace used for welding.

Here, the copper clad laminate refers to a laminated structure of the copper substrate 3 and the insulating layer 5 before the wiring pattern 7 is formed.

In Comparative Example 1 of Fig. 2, an insulating layer was formed by heating and laminating a high heat resistant resin similar to that of Example 1-a and Example 1-b on a copper substrate. The insulating layer is formed of a copper-clad laminate using a polyimide film.

In Comparative Example 1, as shown in Fig. 2, the heat treatment conditions were high at the time of lamination, and it was heated at 350 ° C / 30 min. The annealing hardness of the copper substrate occurred as Hv57. Therefore, the hardness before and after heating is greatly different, the hardness cannot be maintained after heating, and the variation in flatness and flatness after the processing is deteriorated, and the workability (the collapse property of the processed product is ×) cannot be ensured. The hardness after heating at 260 ° C (refer to the reflow oven temperature) is lowered, and high-temperature durability (×) cannot be obtained.

Comparative Example 2 was heated at 180 ° C / 3 hr below 260 ° C to form an insulating layer on a copper substrate (a composition in which an insulating inorganic filler was dispersed in an epoxy resin), and heat treatment conditions were low when laminating, and copper did not occur. Annealing of the substrate. Therefore, workability (the indentation property of the processed product is ○) can be ensured. However, when heat treatment (heating in a reflow furnace or the like) is performed at a temperature of 260 ° C or higher, annealing is likely to occur, so that the life of the substrate is shortened. Further, when the product is used at a temperature of 260 ° C or higher, annealing also occurs, resulting in a shortened life.

On the other hand, in Example 1-a and Example 1-b of Fig. 2, an insulating layer was formed by heating and laminating a high heat resistant resin on a copper substrate, and the heat treatment conditions were high at the time of lamination, but the copper substrate was not annealed. Therefore, the hardness before and after heating is almost unchanged, and the change is suppressed. The hardness can be maintained after heating, and the flatness after the processing can be maintained, and the variation in flatness is small, and the workability (the collapse property of the processed product is ○) can be ensured. The hardness after heating at 260 ° C (reference reflow oven temperature) is high, and high-temperature durability (○) is also obtained.

As described above, in the copper-clad laminates of Comparative Examples 1 and 2, the results were low in high-temperature durability. On the other hand, in the copper-clad laminate of Example 1-a and Example 1-b, the high-strength property of the processed article was high in the collapse property and high-temperature durability.

Further, when the copper-based circuit board 1 is encapsulated with a resin, the filling of the insulating resin can be performed accurately and accurately, and the bending or the like due to shrinkage during curing of the sealing material can be suppressed, and the shape, size, and appearance quality of the product can be maintained.

When the heat sink is attached to the other side surface 3b of the copper substrate 3, the adhesion can be maintained because the flatness can be maintained, and the heat dissipation property of the copper substrate 3 itself can be further improved.

In the formation of the laminate, for example, the surface of the copper substrate 3 formed of the copper alloy of the above-described Example 1-a is subjected to a roughening treatment (for example, chemical treatment) and a film treatment (for example, a plating treatment), and for the high heat resistant resin, 260. Heating at °C~400°C to form a copper clad laminate.

In the case of the roughening treatment, the copper substrate 3 and the insulating layer 5 are strongly bonded to each other, and in the case of the film treatment, when the layer is formed by heating at 260 to 400 ° C, the metal ions from the copper substrate 3 can be suppressed. The oxidation of the insulating layer 5 is suppressed, and the insulation between the insulating layer 5 and the copper substrate 3 can be suppressed. Stripped.

Since the flatness of the copper substrate 3 can be maintained after the formation of the laminate by heating at 260 ° C to 400 ° C, it is possible to further suppress the peeling between the insulating layer 5 and the copper substrate 3.

Further, since it is a copper substrate 3, it has excellent thermal conductivity, can improve heat dissipation, and has high heat resistance of the insulating layer 5. Therefore, a copper-based circuit board 1 suitable for applications requiring high heat dissipation such as a power module can be obtained.

Fig. 4 is a graph showing the composition of a copper substrate.

A copper substrate having a substrate (C15100, C15150, C19400) having the composition of Fig. 4 can also be used in the embodiment of the present invention. In the copper substrate of the composition, the annealing of the copper substrate does not occur at a temperature of 260 ° C or higher compared to the pure copper substrate, and the heating is not the same as in the above-mentioned Embodiment 1-a and Example 1-b. The hardness changes before and after, the hardness can be maintained after heating, and the same effect can be exerted.

Explain the test method.

In the fifth to seventh drawings, the same reference numerals as in the first embodiment are used for the copper-based circuit board sample.

As shown in Fig. 5, the copper-based circuit board sample 1 is punched into a predetermined size by the press of the copper substrate 3 side, and the hole 8 is further processed by the press of the copper substrate 3 side. The copper-based circuit substrate sample 1 was evaluated. The flatness in the present embodiment means that, as shown in FIG. 6, the processed copper-based circuit substrate sample 1 is placed on the fixed disk 10 so as to be in contact with the wiring pattern 7 (circuit Cu foil), and The height of the surface of the copper substrate 3 (the upper surface) is set to 0 in the thickness direction, and the height of the black point (9 points) in the 5th figure which is separated from the center of the sample 1 by 2 mm is measured and the reference point. (0 point) difference. The same measurement was also performed for the sample 1 when it was placed so as to be in contact with the fixed plate 10 on the side of the copper substrate 3.

The difference between the maximum and minimum of 9 points at one point is X (μm) value, and the difference between the maximum and minimum of the other side is Y (μm) value, where the larger of the X and Y values is taken as the flatness. .

In addition, the deviation of the flatness is a standard deviation of 9 points.

The indentation property of the present embodiment is such that the copper base circuit substrate sample 1 is placed such that the wiring pattern 7 (circuit Cu foil) is in contact with the fixed disk 10, and the punched cut edge portion is flatter than the inner flat reference surface. The amount of the extension line depression is used as the amount of depression.

When the amount of indentation is less than 0.15 mm, it is rated as "○", and if it is 0.15 mm or more, it is rated as "X".

The hardness is measured by a copper plate used for a substrate having a thickness of 2 mm or a copper plate of a substrate produced. The center portion in the thickness direction of the cut cross section was measured by the following measuring machine.

Measuring machine: FUTURE-TEC micro Vickers hardness testing machine FM700, measuring load 200g

Further, the hardness after heating at 260 ° C (reference reflow furnace temperature) in Fig. 2 indicates the hardness of the copper plate after heating the substrate at 260 / 2 hr.

In the high-temperature durability test, a hole of φ11 mm is opened to the copper substrate 3, and the M10 bolt and the nut made of SUS304 are locked, and the 260 ° C is repeated. No looseness at room temperature.

The same tests were carried out for Comparative Examples 1 and 2.

8 to 10 are cross-sectional views of a copper-based circuit substrate according to a modification. In addition, the same components as those in the first embodiment are denoted by the same reference numerals.

In the copper-based circuit board 1A of Fig. 8, the wiring pattern 7 is formed on both surfaces of the copper substrate 3 via an insulating layer.

The copper-based circuit board 1B of Fig. 9 is a two-layer substrate (bonding specification). The copper-based circuit board 1B is formed by laminating another substrate 11 on the insulating layer 5 via the adhesive layer 9. The substrate 11 is formed with a wiring pattern 15 of copper foil at the front and back of the glass cloth epoxy resin layer 13. A part of the wiring pattern 15 is electrically connected to the front and back of the glass cloth epoxy resin layer 13 through the through holes.

The copper-based circuit board 1C of Fig. 10 is a two-layer substrate (buildup specification). In the copper-based circuit board 1C, the wiring pattern 19 is formed on the insulating layer 5 via the insulating layer 17 covering the wiring pattern 7, and the wiring pattern 19 is connected to the wiring pattern 7 side through the through hole.

In the copper-based circuit boards 1A, 1B, and 1C according to the modification of the eighth to tenth drawings, the same effects as those of the first to the first embodiments of the first to the first embodiments can be exhibited.

The copper substrate may be formed of a copper alloy containing one or more of Fe, P, Zr, Mg, Zn, and Pb. For any composition, heat treatment is performed at a temperature of 260 ° C to 400 ° C compared to a pure copper substrate. No annealing occurred, and the hardness before and after heating did not change.

Example 2

As shown in Fig. 1, in the copper-based circuit board 1 of the present embodiment, a high heat-resistant resin for forming the insulating layer 5 is replaced by a liquid crystal polymer resin instead of the polyamine used in the embodiment 1-a of Fig. 2. The quinone imine resin was set to have a heat treatment condition of 330 ° C / 20 min. Other conditions are the same as in the embodiment 1-b.

In the present embodiment, the annealing by the heat treatment at the time of lamination did not occur, and the heat treatment was maintained at Hv121 after lamination. Therefore, the hardness before and after heating is the same, the hardness can be maintained after heating, the flatness after processing, The deviation of the flatness is suppressed, and the workability (the collapse property of the processed product is ○) can be ensured. The hardness after heating at 260 ° C (reference reflow oven temperature) is still Hv121, and high temperature durability (○) is also obtained.

That is, in the present embodiment, the same operational effects as those of the above embodiment can be exerted.

Further, the copper-based circuit boards 1A, 1B, and 1C according to the modifications of the eighth to tenth drawings can be similarly applied.

Example 3

As shown in Fig. 1, in the copper-based circuit board 1 of the present embodiment, the high heat-resistant resin for forming the insulating layer 5 is made of a cyanate resin instead of the polyamine used in the embodiment 1-a of Fig. 2; The quinone imine resin was subjected to a heat treatment condition of 300 ° C / 60 min. Other conditions are the same as in the embodiment 1-b.

In the present embodiment, annealing by heat treatment at the time of lamination did not occur, and the hardness after heat treatment at the time of lamination was Hv122. Therefore, the hardness before and after heating is approximately the same, the hardness can be maintained after heating, and the variation in flatness and flatness after the processing is suppressed, and the workability (the collapse property of the processed product is ○) can be ensured. The hardness after heating at 260 ° C (reference reflow oven temperature) is still Hv 122, and high temperature durability (○) is also obtained.

That is, in the present embodiment, the same operational effects as those of the above embodiment can be exerted.

Further, the copper-based circuit boards 1A, 1B, and 1C according to the modifications of the eighth to tenth drawings can be similarly applied.

1‧‧‧Bronze-based circuit board

1a‧‧‧Pressing and cutting department

3‧‧‧ copper substrate

3a‧‧‧ side

3b‧‧‧Other side

5‧‧‧Insulation

7‧‧‧Wiring pattern

Claims (7)

A copper-based circuit board is a copper-based circuit board in which a wiring pattern is formed on one side of a copper substrate via an insulating layer, wherein the insulating layer is formed of a high heat resistant resin; The temperature at which the change in hardness is suppressed is formed by a copper alloy mainly composed of Cu which is higher than the copper substrate of pure copper; even if the insulating layer is formed on the side surface of the copper substrate at a temperature higher than the temperature at which the pure copper starts to be annealed, the insulating layer can be maintained. The use of a pure copper copper substrate to form a laminate has high performance in terms of mechanical workability, substrate flatness, and flatness, and high temperature durability can be maintained. The copper-based circuit board according to claim 1, wherein the copper substrate is formed of a copper alloy containing one or more of cerium, phosphorus, zirconium, magnesium, zinc, and lead. The copper-based circuit substrate according to claim 2, wherein the copper substrate is formed of a copper alloy containing at least 97.0% by weight and less than 100% by weight of Cu. The copper-based circuit board according to any one of claims 1 to 3, wherein the insulating layer is formed of a resin having a temperature of 260 to 400 ° C formed by lamination with the copper substrate. The copper-based circuit board according to claim 4, wherein the resin constituting the insulating layer is a polyimide resin, a polyamidide resin, a polyphenylene sulfide resin, a polyether sulfone resin, Any of a fluorine resin, a polydiether ketone resin, a liquid crystal polymer, a polyethylene terephthalate resin, a polybutylene terephthalate resin, and a cyanate resin. The copper-based circuit board according to any one of the preceding claims, wherein the insulating layer is formed using a composition in which an inorganic filler having a thermal conductivity of 20 W/mk or more is dispersed. The copper-based circuit board according to any one of claims 1 to 6, wherein the insulating layer has a thermal conductivity of 6 to 40 W/mk.