JP6680930B2 - heater - Google Patents

Description

  The present invention relates to a heater, and more particularly to a heater for bonding semiconductor chips for bump welding and the like.

  Patent Document 1 discloses a semiconductor chip bonding head in which a large number of cooling fins are provided on the lower surface of a plate-shaped portion of a suction tool. The semiconductor chip bonding head disclosed in Patent Document 1 sucks and holds a semiconductor chip with a suction tool having a suction hole, and heats the semiconductor chip with a heater plate through the suction tool.

  After that, the heated semiconductor chip is pressed against a predetermined mounting location on the mounting substrate, and the bumps provided on the semiconductor chip and the solder layer provided on the mounting substrate are melted. Next, cold air is supplied to the cooling air passage formed in the suction tool, and the melted solder is cooled and solidified.

JP, 2003-303856, A

  However, in this type of heater, the portion that is directly heated by the heating element that is the heat source is the heater plate. Therefore, after turning off the heating element, it is necessary to effectively cool the upstream of heat transfer, like the heater plate. Nevertheless, the object disclosed in Patent Document 1 is the solder to be cooled, and the downstream side of the heat transfer is cooled, so the cooling effect is limited.

  Therefore, an object of the present invention is to enhance the cooling effect of the heater plate in order to avoid the above inconvenience.

In order to solve the above problems, the heater of the present invention is
In the heater for connecting the connection target to the substrate through the connecting material,
A heating element for welding the connecting material,
A flow path for cooling air for cooling the connecting material heated by the heating element,
An insulating pedestal having a flow path for the cooling air,
A heater plate disposed opposite to the heat insulation base,
A plurality of concavo-convex portions are formed in the flow path of the cooling air on the surface facing the heater plate and the heat insulating pedestal.

  Furthermore, it is preferable that the plurality of uneven portions are arranged based on a predetermined pattern. The plurality of concave and convex portions may be arranged in a staggered pattern.

It is a perspective view which shows the heater of embodiment of this invention typically. It is an exploded view of FIG. It is sectional drawing in the cutting plane AA shown in FIG. It is a typical top view of the heater plate of this embodiment. It is a figure which shows the measurement result about the heater shown in FIG. It is the perspective view seen from the heat insulation base 20 of the heater board 40 which concerns on Embodiment 2 of this invention. It is sectional drawing in AA of the heater plate 40 shown in FIG. It is a figure which shows the measurement result of the surface temperature of the heater plate 40 shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view schematically showing a heater according to the first embodiment of the present invention. As shown in FIG. 1, the heater of this embodiment is roughly divided into a mounting pedestal 10, a heat insulating pedestal 20, a heater plate 40, a fastening member 50, and a hollow bolt 80, which will be described below.

  The mounting pedestal 10 is for mounting the heater body on the movable base of the flip chip bonder. The mounting base 10 can be made of, for example, stainless steel (SUS303, 304, 316, etc.), titanium, or Super Invar. As an example, the mounting base 10 may have a size of 32 mm × 49 mm × 22 mm.

  The mounting base 10 is formed with a flow path 11 of suction air for sucking a semiconductor chip (connection target) (not shown). Further, the mounting base 10 is formed with a flow path 13 for cooling air for cooling the heater plate 40.

  Note that a washer may be provided between the mounting pedestal 10 and the heat insulating pedestal 20 in order to prevent the cooling air from leaking into the gap caused by the difference in the thermal expansion coefficients of the mounting pedestal 10 and the heat insulating pedestal 20 when the heating element is turned on. . The washer can be made of, for example, silicon, Teflon (registered trademark), or polyimide.

  Further, in order to prevent the sucked air from leaking between the hollow bolt 80 and the heat insulating pedestal 20, a ring may be provided between them. The torus may be made of stainless steel (SUS314, 316, etc.), for example.

  The heat insulating pedestal 20 shields heat from the heating element. The heat insulating pedestal 20 can be made of, for example, adcelam, mullite, or macerite. As an example, the heat insulating pedestal 20 may have a size of 36 mm × 49 mm × 14 mm. Inside the heat insulating pedestal 20, a flow path of cooling air (not shown) connected to the flow path 13 of the mounting pedestal 10 is formed. The heat insulating pedestal 20 is fixed to the mounting pedestal 10 by a fastening member 50 such as a bolt or a screw.

  A groove 21 (FIG. 4) forming a flow path of cooling air is formed on the surface of the heat insulating pedestal 20 on the heater plate 40 side. The groove 21 is connected to the cooling air passage 13 formed in the heat insulating pedestal 20. When the cooling air passes through the groove 21, the heater plate 40 is cooled, and heat is transferred to cool and solidify the following bonding portion between the conductive bonding material and the substrate.

  The heater plate 40 has a heating element printed in a desired form, and is for uniformly transmitting heat from the heating element to a conductive bonding material such as a metal bump or a solder bump and a substrate. . The heater plate 40 can be made of, for example, aluminum nitride, silicon nitride, alumina, or silicon carbide. As an example, the heater plate 40 may have a size of 32 mm × 32 mm × 1.5 mm.

  Further, the heater plate 40 is formed with a hole through which the hollow bolt 80 is passed. This hole is connected to the flow path 11 of suction air for sucking the semiconductor chip through the hollow portion of the hollow bolt 80. Therefore, if the semiconductor chips are selectively attached to the heater plate 40 via the attachment tool while air is adsorbed, the semiconductor chips can be transported by the heater.

  The heater plate 40 may be provided with the heating element itself instead of forming the print type heating element on the heater plate 40.

  The hollow bolt 80 connects the heat insulating pedestal 20 and the heater plate 40. The hollow bolt 80 has a small coefficient of thermal expansion, such as titanium, Kovar, molybdenum, tungsten, and chrome (approximately 3.0 × 10 −6 to 10.0 × 10 −6). Can be

  As an example, the hollow bolt 80 may have a size of φ1.4 × 10 mm. For example, the hollow bolt 80 has a hollow structure in which the periphery of the axial center thereof penetrates, and the suction air is configured to pass therethrough. The hollow portion can have a diameter of about 0.4φ to 0.5φ.

  In the heater of the present embodiment, a bolt having no hollow structure may be used instead of the hollow bolt 80. It suffices that the heater has a flow path connected to the flow path 11 for sucking air, and can perform air suction through the flow channel to suck the semiconductor chip.

  The heater according to the present embodiment further includes electrodes, lead wires, and metal fittings (not shown). The electrodes are for turning on the heating element by energization, that is, for raising the temperature of the heating element. The lead wire connects the electrode and the heating element. The restraining metal is for defining the position of the lead wire.

  The heater of the present embodiment can also be attached with an adjusting plate (not shown). This adjusting plate is attachable to and detachable from the heater, and regulates the direction of the cooling air that has passed through the groove 21 formed in the heat insulating pedestal 20. When the adjustment plate is not attached to the heater, the cooling air travels in the surface direction of the heat insulating pedestal 20. On the other hand, when the adjusting plate is attached to the heater, after advancing in the surface direction of the heat insulating pedestal 20, it is received by the air receiving surface of the adjusting plate and advances in the direction corresponding to the angle.

  It should be noted that the size of each of the above parts is appropriately changed according to the size of the entire heater, as is clear from the example given above.

  FIG. 2 is a schematic view of a surface of the heater plate 40 shown in FIG. 1 that faces the heat insulating pedestal 20. FIG. 3 is an enlarged view of portion B in FIG. As shown in FIGS. 2 and 3, the heater plate 40 is provided with a convex portion 43. The convex portion 43 enhances the cooling effect of the heater plate 40.

  The convex portion 43 may be provided on the entire surface of the heater plate 40, but it is not always necessary and is provided only on a surface facing the heat insulating pedestal 20 and at least at a position corresponding to the groove 21 of the heat insulating pedestal 20. Good. It suffices that each convex portion 43 is provided under the condition that a swirl or turbulent flow is generated in the cooling air, and its shape may be, for example, a hemispherical shape, a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, a rectangular tube shape, or the like. It is also possible to combine these appropriately.

  Further, in the present specification, forming the convex portion 43 on the heater plate 40 also includes forming the surface into a satin finish. In such a case, it may not be possible to generate a swirl or turbulent flow in the cooling air, but the surface area of the heater plate 40 facing the heat insulating pedestal 20 can still be increased, and accordingly, The cooling efficiency of the heater plate 40 is increased.

  In the case of a hemispherical object, each convex portion 43 has a maximum diameter of, for example, φ0.05 mm to φ3.00 mm, a height of 0.02 mm to φ1.00 mm, and a pitch between adjacent convex portions of 0. The size can be 16 mm to 1.60 mm.

  Further, instead of providing the respective convex portions 43, a plurality of concave portions may be provided under the condition that a similar function can be realized, or instead of or together with these, a plurality of concave portions in the groove 21 of the heat insulating pedestal 20. Alternatively, a convex portion may be provided. In this way, a swirl or turbulence may be generated in the cooling air. To summarize the above, in the present embodiment, a plurality of uneven portions are formed in the flow path (including the groove portion 21) of the cooling air in the facing surface between the heater plate 40 and the heat insulating pedestal 20.

  Although FIG. 2 and FIG. 3 show an example in which the plurality of convex portions 43 are arranged in a staggered pattern, they may be arranged in a lattice pattern or may be arranged in a honeycomb pattern. Good. The heater plate 40 is not limited to this, but the convex portion 43 may be integrally formed by molding.

  FIG. 4 is a diagram showing a part of the AA cross section of FIG. 1. FIG. 4 shows a cross section of the heater plate 40 and the heat insulating pedestal 20 described above. Further, the groove 21 of the heat insulating pedestal 20 is also shown in FIG. 4.

  The heating / cooling process of the heater according to this embodiment will be described with reference to FIG. First, in the heater heating step, the heater attached to the movable base of the flip chip bonder adsorbs the semiconductor chip by adsorption air. Specifically, the suction air passes through the hollow portion of the hollow bolt 80, the suction air flow passage provided in the heat insulation pedestal 20, and the suction air flow passage 11 provided in the mounting pedestal 10, and is not shown in the drawing. Drawn by.

  When the suction air passes through the hollow portion of the hollow bolt 80 as in the heater of this embodiment, the cooling air will not be mixed with the suction air. The semiconductor chip, while being attracted by the heater, is transported toward the substrate to which it is attached. As is known, a conductive bonding material (connecting material) is formed on the substrate and is aligned with the substrate.

  Then, the heating element of the heater is turned on by the electrode and the lead wire, and, for example, the heating element is heated to about 400 ° C to 450 ° C. The heater heating process described above is a known method.

  Next, the heater cooling process will be described. After the metal bumps (connecting material) are melted by the heating step, cooling air is supplied in a state where the semiconductor chip is sucked by suction air.

  Then, the cooling air reaches the groove 21 formed in the heat insulating pedestal 20 through the flow path 13 of the cooling air formed in the mounting pedestal 10 and the flow path of the cooling air formed in the heat insulating pedestal 20. To do. Then, the cooling air cools the semiconductor chip, the conductive bonding material, and the substrate through the heater plate 40. That is, the cooling air flows through the groove 21 provided in the heat insulating pedestal 20 to cool the surface of the heater plate 40 facing the heat insulating pedestal 20.

  The cooling air hits the convex portion 43 provided on the heater plate 40 when flowing through the groove 21 provided on the heat insulation pedestal 20. Then, the flow of the cooling air flowing through the groove 21 of the heat insulating pedestal 20 changes, and the cooling air advances while being stirred in the groove 21. In other words, the convex portion 43 causes the cooling air flowing through the groove 21 of the heat insulating pedestal 20 to become a vortex or a turbulent flow. Then, even at the downstream side of the cooling air, relatively low temperature cooling air reaches the heater plate 40, so that the cooling effect is enhanced.

  Further, the surface area of the surface of the heater plate 40 facing the heat insulating pedestal 20 is increased by the amount of the protrusion 43, as compared with the case of using the heater plate not provided with the protrusion 43. This alone increases the cooling effect of the heater plate 40 due to the increase in the contact area between the cooling air and the heater plate 40.

  FIG. 5: is a figure which shows the measurement result of the surface temperature of the heater plate 40 shown in FIG. For comparison, FIG. 5 also shows the surface temperature of the heater plate on which the convex portion 43 is not provided. Here, the flow rate of the cooling air is 100 NL / min.

  First, when the heating element is turned on, the surface temperature of the heater plate 40 reaches about 450 ° C. within just a few seconds. Then, the heating element is kept on for about 10 seconds.

  After that, the heating element is turned off and the blowing of cooling air is started. As a result, the flow rate of the cooling air is increased to about 100 NL / min, and that state is maintained. Further, the cooling air lowers the surface temperature of the heater plate 40.

  Here, in the case of the heater of the comparative example, the time from when the heating element is turned off until the surface temperature of the heater plate 40 is lowered to about 100 ° C. is about 10 seconds. On the other hand, in the case of the heater of the present embodiment, the time from when the heating element is turned off until the surface temperature of the heater plate 40 decreases to about 100 ° C. is about 4 seconds.

  As described above, in the main measurement, in the case where the convex portion 43 is provided on the surface of the heater plate 40 facing the heat insulating pedestal 20, as compared with the case where the convex portion is not provided, the surface of the heater plate 40. The time it takes for the temperature to drop from about 450 ° C to about 100 ° C can be reduced by about 2 seconds. In other words, the heater of this embodiment can shorten the cooling time by about 20%.

(Embodiment 2)
FIG. 6 is a perspective view of the heater plate 40 according to the second embodiment of the present invention viewed from the heat insulating pedestal 20. FIG. 7 is a cross-sectional view taken along line AA of the heater plate 40 shown in FIG. The heater plate 40 of the present embodiment is provided with a plurality of cooling air passages 43 formed inside from the surface on the side of the heat insulating pedestal 20 toward the opposite surface thereof and connected to the grooves 21 of the heat insulating pedestal 20, A plurality of cooling air channels 47 are formed integrally with the channels 43 and extend to the side surface of the heater plate 40 in a direction orthogonal to the channels 43.

  In addition, in the case of the present embodiment, it is not necessary to form the groove 41 as shown in FIG. 4 in the heat insulation pedestal 20, and the flow path of the cooling air is formed at the position corresponding to the flow path 43 of FIG. It is also possible.

  As shown in FIG. 6, for example, the heater plate 40 is provided with ten channels 47 as a whole, and the channels 43 are provided for the five channels 47, respectively. ing. These numbers are examples, and the number may be larger or smaller than this, but it is preferable that the heater plate 40 is provided as a whole so as to be uniformly cooled.

  Further, as an example, assuming that the heater plate 40 has a thickness of about 1.5 mm to 2.5 mm, the diameter of the flow path 47 for the cooling air is 1/4 times the thickness of the heater plate 40. The size can be about 1/2. However, the diameter of the cooling air passage 47 may be selected according to the number of the cooling air passages 47.

  The heater plate 40 of the present embodiment is not limited to this, but may be assembled by manufacturing the upper half and the lower half in FIG. 7 and bonding them.

  The cooling air reaches the groove 21 formed in the heat insulating pedestal 20 through the flow path 13 formed in the mounting pedestal 10 and the flow path formed in the heat insulating pedestal 20. After that, the cooling air is discharged from the groove 21 toward the flow path 43 and through the flow path 47 to the outside of the heater plate 40.

  As a result, the heater plate 40 is cooled from its surface (the surface on the side of the heat insulating pedestal 20) by the cooling air that has reached the groove 21, and the flow paths 43 and 47 provided inside the heater plate 40 are further separated. Since the heater plate 40 is cooled from the inside by the flowing cooling air, the heater plate 40 has a high cooling effect, which leads to early cooling of the semiconductor chip, the conductive bonding material and the substrate.

  Further, when the flow path 43 and the flow path 47 are provided inside the heater plate 40 as in the present embodiment, compared to the case where these are not provided as in the first embodiment, the cooling air flow Since the outlet area of the flow passage is large, it is possible to flow a large amount of cooling air, and from this point as well, the cooling effect of the heater plate 40 can be enhanced.

  FIG. 8 is a diagram showing the measurement results of the surface temperature of the heater plate 40 shown in FIG. 6, and corresponds to FIG. The point that the ON state is maintained for about 10 seconds after turning on the heating element is the same as in the case of FIG.

  After that, the heating element is turned off and the blowing of cooling air is started. The amount of cooling air supplied was the same as in the first embodiment. The cooling air lowers the surface temperature of the heater plate 40.

  In the case of the heater of this embodiment, the time from when the heating element is turned off until the surface temperature of the heater plate 40 decreases to approximately 100 ° C. is approximately 4.5 seconds. Thus, in this measurement, when the heater plate 40 is provided with the flow paths 43 and 47, the surface temperature of the heater plate 40 is changed from about 450 ° C. to about 100 ° C., as compared with the case where it is not provided. The time to decrease can be shortened by about 5.5 seconds. In other words, the heater of this embodiment can reduce the cooling time by about 65%.

  Although the heaters of the first and second embodiments of the present invention have been described above, a combination of the first and second embodiments may be used. That is, you may use the heater plate which has the convex part 43 and is provided with the flow paths 43 and 47.

10 Mounting Base 11, 13 Flow Path 20 Thermal Insulation Base 21 Groove 40 Heater Plate 41 Hole 43 Convex Part 50 Fastening Member 80 Bolt

Claims (4)

After welding the connection material located between the base material and the connection target and connecting these, to the heater provided with a heat insulation pedestal having a flow path for cooling air for cooling the connection material, to the heat insulation pedestal Heater plates arranged to face each other,
The surface facing the heat insulating pedestal has a plurality of convex portions having a hemispherical shape, a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, a rectangular tube shape or a combination thereof in the cooling air flow path, and the heat insulating pedestal. A heater plate formed with a recess for receiving the head of a fastener for making a connection .   The heater plate according to claim 1, further comprising a flow path of the cooling air formed from a position corresponding to the flow path to a side surface.   The heater plate according to claim 1, wherein a heating element that transfers heat during the welding is printed. The heater plate according to claim 1, wherein the convex portions are arranged in a staggered pattern, a lattice pattern, or a honeycomb pattern.

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