JP4493026B2 - Method for manufacturing circuit board with cooling device - Google Patents

Description

  The present invention relates to a circuit board with a liquid cooling type cooling device that radiates heat from a substrate whose temperature rises, and a method for manufacturing the circuit board.

Conventionally, as a liquid cooling type cooling device for radiating heat from a circuit board, for example, there is one shown in Patent Document 1. FIG. 4 is an explanatory diagram of a circuit board having a conventional cooling device. As shown in FIG. 4, the circuit board having this cooling device is such that a heat radiation base plate 102 is placed on a water cooling module 100 such as a corrugated fin-type heat sink via a thermal conductive grease 101, and the circuit board is formed thereon with solder 103. 104 and an electronic component 105 such as a semiconductor chip are joined and fixed by connecting means such as a screw.
Also, when the thermal expansion coefficient of the water-cooled module and the circuit board are close, or when the circuit board is small and the stress due to the difference in thermal expansion can be ignored, the thermal conductivity is improved by joining by soldering etc. .

In recent years, electronic components have been miniaturized, and in particular, in the field of power module substrates such as CPU chip mounting substrates and power device mounting substrates, the amount of heat radiation required per unit area is very large.
However, as described above, in the conventional structure, since a water cooling module, thermal conductive grease, a joining brazing material, etc. are used, the heat resistance to the water cooling heat transfer surface in contact with the cooling water is large and it is difficult to improve the cooling performance. There were drawbacks.
Japanese Patent Laid-Open No. 2002-185175, FIG.

  Accordingly, in view of the above-described circumstances, the problem to be solved by the present invention is to provide a circuit board with a cooling device and a method for manufacturing the same, which has a very large heat dissipation amount with respect to a circuit board of a power module and the like. There is to do.

  In order to solve the above problems, a circuit board with a cooling device according to the present invention includes a circuit board having a circuit pattern for mounting an electronic component on one surface, and a flow formed on the other surface of the circuit board. The cooling liquid is circulated through a fine flow path portion formed by the flow path pattern and a plate member superimposed on the other surface side of the circuit board via the flow path pattern.

  The circuit board with a cooling device according to the present invention includes a pair of circuit boards having a circuit pattern for mounting electronic components on one surface, and a flow path pattern formed on the other surface of each circuit board. Each of the circuit boards is overlapped, and the cooling liquid is circulated through the fine flow path portion formed by the flow path pattern.

  Preferably, the flow path pattern has a fine fin structure including a plurality of pin portions.

  In the method for manufacturing a circuit board with a cooling device according to the present invention, a circuit board having a circuit pattern for mounting an electronic component on one side is prepared, and a flow path pattern is screened on the other side of the circuit board. A plate member formed by printing and bonded to the circuit board is prepared, and the circuit board and the plate member are overlapped via the flow path pattern, and solid phase bonding or melt bonding is performed. A fine channel part for circulating the coolant is formed between the two.

  In the method for manufacturing a circuit board with a cooling device according to the present invention, a circuit board having a circuit pattern for mounting an electronic component on one side is prepared, and a first flow path is provided on the other side of the circuit board. A pattern is formed by screen printing, and a plate member to be bonded to the circuit board is prepared. On this plate member, a second flow path pattern that is mirror-image-symmetric to the first flow path pattern is formed by screen printing. With the circuit pattern matched, the circuit board and the plate member are overlapped through each flow path pattern and solid phase bonded or melt bonded, and the coolant is circulated between the circuit board and the plate member by the flow path pattern. The fine flow path part to be formed is formed.

  Since the circuit board with a cooling device according to the present invention is configured as described above and does not involve heat conductive grease or brazing material, the thermal resistance from the electronic component serving as a heat source to the water-cooled heat transfer surface is extremely high. Since the cooling liquid directly cools the circuit board, the temperature rise of the electronic component can be greatly reduced.

  Hereinafter, a circuit board with a cooling device and a manufacturing method thereof according to the present invention will be described in detail based on the drawings.

  1A and 1B show a circuit board with a cooling device according to the present invention, in which FIG. 1A is a plan view, FIG. 1B is a side view, and FIG. FIG. 2 is a diagram for explaining a method of manufacturing a circuit board with a cooling device. FIG. 3 is a diagram for explaining the experimental evaluation.

  As shown in FIG. 1, the circuit board with a cooling device includes a pair of circuit boards 1 and 2. Each of the circuit boards 1 and 2 may be made of an epoxy resin, bakelite, ceramic or the like, but is preferably an alumina substrate or an aluminum nitride substrate having high thermal conductivity. Each circuit board 1, 2 has circuit patterns 11, 12 for mounting electronic components formed on one surface made of a copper thick film electrode material or an aluminum thick film material.

  Each circuit board 1, 2 has a flow path pattern 3 formed on the other surface, and is overlapped via the flow path pattern 3. The flow path pattern 3 is formed of a copper thick film electrode material or an aluminum thick film electrode material, similarly to the circuit patterns 11 and 12. And the thickness of this circuit board with a cooling device is about 1.8 mm. As shown in FIG. 1 (a), the flow path pattern 3 is formed on the periphery 3 'around each circuit board 1 and 2, and on the inner side of the periphery 3'. And a pin portion 3 ″. In this embodiment, the pin portion 3 ″ has a diameter of about 0.3 mm, a pitch of about 0.6 mm, and a height of about 0.5 mm. The flow path pattern 3 may have a parallel fin structure or the like.

  Since the flow path pattern 3 has a predetermined thickness, the fine flow path portion for allowing the coolant 6 to pass through the space portion formed between the peripheral portion 3 ′ and the plurality of pin portions 3 ″. 3a is formed. Then, the coolant joints 4 and 5 are connected to the fine flow path portion 3, and the coolant 6 is introduced from the coolant joint 4 and the circuit boards 1 and 2 (electronic components) through the fine flow path portion 3a. Is cooled, discharged from the coolant joint 5 and circulated. That is, the coolant 6 is sealed in the circuit boards 1 and 2 at the peripheral portion 3 ′, and the circuit boards 1 and 2 are radiated from the surface of each pin portion 3 ″.

  The circuit board with a cooling device of the present embodiment has circuit patterns 11 and 12 for mounting electronic components on one surface of both circuit boards 1 and 2. A plate member made of alumina or the like having the circuit pattern 11 only on the circuit board 1 and not having the circuit pattern 12 may be used as the other circuit board 2.

  Next, a method for manufacturing the circuit board with a cooling device will be described. First, as shown in FIG. 2A, a pair of circuit boards 1 and 2 having substantially the same size is prepared. Then, as shown in FIG. 2B, circuit patterns 11 and 12 are formed on one surface 1a and 2a of each circuit board 1 and 2 using screen printing. Further, a first flow path pattern 30 is formed on the other surface 1b of the circuit board 1 by screen printing, and a second image mirror-symmetrical to the first flow path pattern 30 is formed on the other surface 2b of the circuit board 2. The flow path pattern 31 is formed by screen printing.

  Then, each pattern 11, 12, 30, 31 is fixed on the board | substrates 1 and 2 by baking at high temperature. When the pattern material is copper, it is baked in nitrogen at 800 to 1000 ° C., and when aluminum is 550 to 700 ° C. The first and second flow path patterns 30 and 31 repeat printing and baking a plurality of times to ensure a predetermined height as a fine flow path portion and form a flow path cross section with an increased aspect ratio.

Then, the circuit boards 1 and 2 are stacked and fired in a state where the first and second flow path patterns 30 and 31 are aligned with each other at the same position. As a result, as shown in FIG. 2C, the first and second flow path patterns 30 and 31 are integrally formed by solid phase bonding or fusion bonding, and a flow path having a predetermined thickness is formed between the circuit boards 1 and 2. Pattern 3 is formed.
The first and second flow path patterns 30 and 31 do not have to be mirror-symmetrical, and may be formed only on the other surface 1b or 2b of each circuit board 1 or 2. The flow path pattern may be bonded to one circuit board by baking, and the other circuit board may be pressed against the flow path pattern and refired to be integrated.
And since the flow path pattern 3 to be fired in an overlapping manner can be formed using screen printing, the flow path design has a high degree of freedom and a mold is not required, so that the manufacture of prototypes and design changes can be made inexpensive. Can do. Furthermore, since the flow path pattern 3 can be miniaturized by screen printing, the heat radiation area by the fine flow path portion can be increased, and the efficiency of heat transfer can be improved.

  Thereafter, as shown in FIG. 2 (d), electronic components 21 and 22 such as semiconductor chips and transistors are mounted on the circuit patterns 11 and 12 of the circuit boards 1 and 2, and the electronic components 21 and 22 are connected by wire bonding. The circuit patterns 11 and 12 are electrically connected by the wire 13. Then, as shown in FIG. 2E, after the leads 15 are drawn out from the circuit boards 1 and 2 and sealed with the mold resin 14, the coolant joints 4 and 5 are inserted and coupled with a sealing material. Thus, a hybrid integrated circuit using the circuit board with a cooling device of the present invention is manufactured.

Next, experimental evaluation of a circuit board with a cooling device will be described. As shown in FIG. 3, each of the circuit boards 1 and 2 was provided with one semiconductor chip 21 and 22, respectively, and an evaluation experiment was performed. Each of the circuit boards 1 and 2 has a length of 3.0 cm, a width of 5.0 cm, and a height of 1.8 mm. The power consumption Q of the semiconductor chips 21 and 22 is 200 [W] × 2 chips = 400 [W]. At this time, the coolant temperature Ta introduced from the coolant joint 4 is about 30 ° C., the coolant temperature Tb discharged from the coolant joint 5 is about 52 ° C., and the junction temperature Tj of the semiconductor chips 21 and 22 is 71 ° C. there were.
Accordingly, the thermal resistance θ of the semiconductor chip 21 based on the supply cooling water temperature Ta per semiconductor chip is (Tj−Ta) / Q = (71−30) / 200 = about 0.2 [° C. / W].

The above results show that the substrate can tolerate a loss of 400W. When the allowable power at this time is converted into the heat generation density per unit area, the heat generation density corresponds to 27 [W / cm ² ] from 400 [W] (total power) ÷ 15 [cm ² ] (substrate area), which is extremely high. Demonstrate high performance.
Then, for a circuit board of the same area, when comparing a conventional water-cooling module using thermal conductive grease and the circuit board with a cooling device according to the present invention, a semiconductor device mounted on the circuit of the present invention The temperature rise of the current can be reduced to about 30 to 70% compared with that of the conventional structure.

The circuit board with a cooling device which concerns on this invention is shown, (a) is a top view, (b) is a side view, (c) is the II sectional view taken on the line of (b). It is a figure for demonstrating the manufacturing method of a circuit board with a cooling device. It is a figure for demonstrating experiment evaluation. It is explanatory drawing of the circuit board which has the conventional cooling device.

Explanation of symbols

1 Circuit board 2 Circuit board (plate member)
1a, 2a One side 1b, 2b of the circuit board (plate member) The other side 3 of the circuit board (plate member) 3 Flow path pattern 3 '' Pin part 3a of the flow path pattern Fine flow path parts 4, 5 Cooling joint 6 Coolant 11, 12 Circuit pattern 14 Sealing resin 15 Draw lead

Claims (2)

  A circuit board having a circuit pattern for mounting an electronic component on one side is prepared, a flow path pattern is formed on the other side of the circuit board by screen printing, and a plate member to be bonded to the circuit board is prepared. Then, the circuit board and the plate member are overlapped via the flow path pattern and solid phase bonded or melt bonded, and the coolant is circulated between the circuit board and the plate member by the flow path pattern. A method of manufacturing a circuit board with a cooling device, comprising forming a fine channel portion.   A circuit board having a circuit pattern for mounting an electronic component on one side, a first flow path pattern formed on the other side of the circuit board by screen printing, and a board to be joined to the circuit board A member is prepared, and a second flow path pattern that is mirror-symmetrical to the first flow path pattern is formed on the plate member by screen printing, and the flow path patterns are combined with each flow path pattern. The circuit board and the plate member are overlapped with each other via a solid phase bonding or melt bonding, and the flow path pattern forms a fine flow path portion for circulating a coolant between the circuit board and the plate member. A method of manufacturing a circuit board with a cooling device.

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