JP2020025141A - Bonding head and mounting device - Google Patents

Abstract

To provide a bonding head which is excellent in cooling performance and does not adversely affect mounting quality even after repetitions of heating and cooling, and a mounting device including the same.SOLUTION: There are provided: a bonding head which includes an attachment tool holding an electronic component on a lower face thereof, a heater disposed at the top of the attachment tool, and an insulation block disposed at the top of the heater, and which has, on an upper face side of the heater, a plurality of plate-like walls formed by providing a plurality of parallel grooves, the plate-like walls having a gap at an interface with the lower face of the insulation block by lowering the top of the plate like walls with respect to an upper face of the heater; and a mounting device including the same.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a bonding head used for heat-pressing an electronic component such as a semiconductor chip on a wiring board or the like, and a mounting apparatus having the same.

  As a method for mounting an electronic component such as a semiconductor chip on a substrate such as a wiring board, a flip chip method is known. In the flip chip method, the electrodes of the electronic component and the electrodes of the substrate are bonded by thermocompression bonding using a mounting apparatus 1 as shown in FIG.

  In the mounting apparatus 1 shown in FIG. 5, first, the electronic component C is arranged at the tip of the bonding head 2 by an electronic component delivery mechanism (not shown) and held by the bonding head 2. After that, the alignment marks provided on the substrate B held on the substrate stage 4 and the alignment marks provided on the electronic component C are recognized by the image recognition means 5, and the alignment is performed. At the time of positioning, at least one of the bonding head 2 and the substrate stage 4 is moved in an in-plane direction (XY direction and θ direction) parallel to the substrate B. After the alignment, the bonding head 2 is moved down by the bonding unit 3 and the electronic component C is pressed against the substrate B while heating and heating, and the electrode of the electronic component C and the electrode of the substrate B are joined. When the bonding is completed, the bonding head 2 releases the holding of the electronic component C, moves up by the bonding unit 3, holds the electronic component C to be mounted next at the tip, and performs the above-described series of operations.

  Here, the bonding head 2 has a configuration as shown in FIG. That is, the bonding head 2 includes an attachment tool 20 that suction-holds the electronic component C on the lower surface, a heater 21 disposed above the attachment tool 20, and a heat insulating block 22 disposed above the heater 21. The electronic component C is heated by heating the heater 21 having a function of raising the temperature of the attachment tool 20. However, in order to efficiently supply the heat of the heater 21 to the electronic component C, heat transfer to the upper part of the heater 21 is performed. The heat insulating block 22 is disposed to suppress the occurrence of the heat. Further, the heat insulating block 22 is connected to a head main body 24 via a holder 23.

  In the flip-chip method, a solder bump is often used as an electrode of an electronic component, and the electronic component that has been heated and pressed on a substrate needs to be cooled until the solder is in a solid state. In recent years, a thermosetting adhesive layer is provided in advance on the surface of the electronic component on the electrode side, and a method of curing the thermosetting adhesive layer during thermocompression bonding has been adopted. In the method, at the stage of holding the electronic component, the temperature of the attachment tool must be lower than the curing start temperature of the thermosetting adhesive layer. For this reason, in a series of tact times, the ratio of time for cooling the heated attachment tool (and the heater) is increasing, and effective cooling means is required from the viewpoint of shortening the tact time.

  For example, Patent Literature 1 introduces a method of air cooling using a cooling blow nozzle provided with an attachment tool and a heater around it. However, in this method, a temperature difference occurs between the air-cooled surface and the inside, so that a significant reduction in the time for cooling to the inside cannot be expected.

  Therefore, a method has been proposed in which a plurality of grooves are provided in a heater, and cooling air is flown from inside the heater into a flow path formed by overlapping the heater and the heat insulating block to cool the heater (for example, Patent Document 2).

  An example is shown in FIG. FIG. 7 shows the heater 21 and the heat insulating block 22 in the bonding head 2 shown in FIG. Also. FIGS. 8 and 9 are three views showing the shapes of the heater 21 and the heat insulating block 22 that constitute the portion shown in FIG. As shown in FIG. 8, a plurality of grooves 21U are provided on the upper surface of the heater 21, and a plurality of tubular channels 21P are formed by overlapping the heat insulating block 22 and the heater 21 shown in FIG. On the other hand, a depression 22D is formed in the heat insulating block 22 so as to extend over all the grooves 21U of the heater 21, and a ventilation hole 22V connected to the depression 22D is provided.

  For this reason, by sending the cooling air to the ventilation holes 22V, the cooling air flows from the vicinity of the center of the heater 21 to both side surfaces (front and rear directions in FIG. 7), and the heater 21 is cooled from the inside. In FIGS. 7 and 8, the groove 21U and the tubular channel 21P are drawn larger for the sake of explanation, but in actuality, a number of grooves 21U (tubular channel 21P) each of which is smaller than 1 mm are formed.

  As described above, the method in which the groove 21U is formed on the upper surface of the heater 21 and the flow path is formed by overlapping with the lower surface 22S of the heat insulating block 22 is capable of cooling the heater 21 from the inside. This is an advantageous cooling method.

JP-A-10-340915 JP 2014-22629 A

  In this method, in FIG. 7, the upper portion 21 </ b> T of the wall 21 </ b> W forming the groove 21 </ b> U comes into close contact with the lower surface 22 </ b> S of the heat insulating block 22. As a result, heat transfer from the upper portion 21T of the wall 21W to the outside is hindered, and there is a problem in the heat radiation characteristics on the uppermost surface of the heater 21. On the other hand, when the temperature of the heater 21 is raised, the heat transfer from the heater 21 to the heat insulating block 22 is present, albeit slightly, so that the temperature of the heat insulating block 22 having low thermal conductivity and little heat dissipation rises. As a result, at the stage of cooling the heater 21, heat is transferred from the adiabatic block 22 (which is in close contact with the heater 21) to the heater 21, causing a problem when cooling the heater 21.

  Further, since the upper portion 21T of the wall 21W is in close contact with the lower surface 22S of the heat insulating block 22, the tubular flow path 21P formed by the groove 21U of the heater 21 and the lower surface 22S of the heat insulating block 22 causes air leakage between them. There is no state. For this reason, if the shape of the tubular flow paths 21P varies (due to, for example, the influence of processing accuracy variation when forming the grooves 21U), the cooling effect differs between the individual tubular flow paths 21P, and cooling unevenness occurs in the heater surface. .

  On the other hand, in this method, since the heater 21 and the heat-insulating block 22 are fixed in the vertical direction by fastening parts near the center, the heater 21 and the heat-insulating block 21 on the contact surface other than near the center are thermally expanded and expanded in the horizontal direction. Can shrink. For this reason, in the form in which the heater 21 having a large number of minute grooves 21U formed on the upper surface and the heat insulating block 22 are overlapped, adverse effects may be caused by repeated heating and cooling.

This adverse effect is caused by the difference between the materials of the heater 21 and the heat insulating block 22. At the time of heating and cooling, a temperature difference is generated at the interface between the heater and the heat insulating member due to a difference in thermal conductivity. Related to the generated stress. For example, when the heater 21 is a combination of aluminum nitride and the heat insulating block 22 is a combination of Adceram (registered trademark), both have the same thermal expansion coefficient of about 5 × 10 ⁻⁶ / K, but the thermal conductivity is 100 times. Due to the difference, a large temperature difference is generated at the interface between the two materials, and a difference in elongation due to thermal expansion occurs. That is, since many narrow grooves 21U are formed on the upper surface of the heater 21, the thin wall 21W (forming the groove 21U) is easily affected by stress, and the upper part 21T of the wall 21W is deformed or generates friction. . Even if such deformation and friction are extremely slight, the upper portion 21T of the wall 21W may be scraped as shown in FIG. 10 while the heater 21 is repeatedly heated and cooled (AB in FIG. 10). , May be damaged (BR in FIG. 10), and the lower surface 22S of the heat insulating block 22 may be scraped. In particular, in the case of ceramics, since the material is hard and brittle, there is a disadvantage that stress is concentrated at the corners of the upper portion 21 of the wall 21W and the chip is easily chipped.

  When the wall 21W forming the groove 21U of the heater 21 or the lower surface 22S of the heat insulating block 22 is scraped or damaged, the abrasion powder PW and the debris BP enter the groove 21U, a part of which is produced to the outside together with the cooling air, and a part thereof. Closes the tubular channel 21P remaining in the groove 21U. Here, the abrasion powder PW and the debris BP discharged to the outside become foreign matters in the mounting atmosphere, and adversely affect the mounting quality of the electronic component C. Further, the wear remaining in the groove 21U obstructs the flow of the cooling air by closing the tubular flow path 21P, thereby causing cooling unevenness.

  The present invention has been made in view of the above problems, and provides a bonding head which is excellent in cooling performance and which does not adversely affect mounting quality even when repeated heating and cooling are performed, and a mounting apparatus using the same. It is.

In order to solve the above problems, the invention described in claim 1 is
A bonding head used for heat compression bonding of an electronic component,
An attachment tool that holds the electronic components on the underside,
A heater disposed on top of the attachment tool;
A heat insulating block disposed above the heater,
On the upper surface side of the heater, a plurality of plate-shaped walls formed by providing a plurality of parallel grooves,
The plate-shaped wall is a bonding head having an upper portion lower than the upper surface of the heater to have a gap at an interface with a lower surface of the heat insulating block.

The invention according to claim 2 is the bonding head according to claim 1,
The bonding head is characterized in that an interval of the gap is 0.3% or more and 40% or less of a depth of the groove.

  According to a third aspect of the present invention, there is provided a mounting apparatus including the bonding head according to the first or second aspect.

  ADVANTAGE OF THE INVENTION By the bonding head of this invention and the mounting apparatus using this, it is excellent in cooling performance, and even if it heats and cools repeatedly, mounting of an electronic component which does not have a bad influence on mounting quality can be performed.

FIG. 3 is a diagram illustrating a heater and a heat insulating block of the bonding head according to one embodiment of the present invention. It is a three-view figure showing the structure of the heat insulation block of the bonding head concerning one embodiment of the present invention. FIG. 7 is a diagram illustrating a heater and a heat insulating block of a bonding head according to another embodiment of the present invention. FIG. 6 is a three-view drawing showing a structure of a heater of a bonding head according to another embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a mounting device. FIG. 3 is a diagram illustrating a configuration of a bonding head. FIG. 4 is a diagram illustrating a heater and a heat insulating block of a bonding head according to a known technique. It is a three-view figure showing the structure of the heater of the bonding head of a well-known art. It is a three-view figure showing the structure of the heat insulation block of the bonding head of a well-known art. FIG. 3 is a diagram illustrating one of the problems of the known technology.

An embodiment of the present invention will be described with reference to the drawings.
The mounting apparatus and the bonding head according to one embodiment of the present invention have a configuration similar to the mounting apparatus 1 shown in FIG. 5 and the bonding head 2 shown in FIG. 1 is an enlarged view of FIG. FIG. 2 is a three-view drawing of the heat insulating block 22 shown in FIG.

  In FIG. 1, the material of the heater 21 is ceramics, in which a heating resistor is embedded. As the ceramics, those having high thermal conductivity (50 W / m · K or more) and excellent electrical insulation are desirable, and aluminum nitride and the like are preferable. On the other hand, ceramics is also used as the material of the heat insulating block 22, but the thermal conductivity is preferably 5 W / m · K or less, and more preferably 1.5 W / m · K or less.

  The heater 21 shown in FIG. 1 has the same shape as that shown in the three views in FIG. 8, and is formed by forming a plurality of grooves 21U having a width of WU and a depth of HU from one side of the upper surface to the opposite side. is there. By forming a plurality of grooves 21U, a plurality of comb-shaped walls 21W are formed. In the heater 21 shown in FIG. 8, the upper portion 21T of the wall 21W has the same height as the upper surface 21S of the heater 21, and the height of the wall 21W is HU. The width of the wall 21W is WT, but the width WT is determined by the width WU of the groove 21U and the formation pitch.

  On the other hand, the heat insulating block 22 of FIG. 1 has a shape of a three-view drawing shown in FIG. The heat insulating block 22 shown in FIG. 2 has a second lower surface 22C unlike the one shown in FIG. The second lower surface 22C is flat and parallel to the lower surface 22S, but has a height difference HG from the lower surface 22S. When the lower surface 22S is placed on a flat surface, the gap 22G has a tunnel shape. The second lower surface 22C has a width such that when the heat insulating block 22 is overlaid on the heater 21, the longitudinal direction of the tunnel shape is parallel to the groove 21U, and a gap 22G is formed in a range including all the grooves 21U. I have.

  In the bonding head 2 provided with the heater 21 and the heat insulating block 22 shown in FIG. 1, at the time of cooling, cooling air is sent into the ventilation holes 22V by a blowing system (not shown), and the sent cooling air passes through the recesses 22D and passes through the grooves 21U. By passing, the heater 21 is cooled from the inside. Although the cooling air also passes through the gap 22G, the cooling air also comes into contact with the upper surface 21T of the wall 21W, so that there is an effect of cooling the heater 21 from the upper surface. This is an effect that the upper surface 21T is difficult to cool because the upper surface 21T of the wall 21W is in close contact with the lower surface 22S of the heat insulating block 22, which is not an effect in the related art.

  On the other hand, due to the low thermal conductivity of air, heat is hardly transmitted from the upper portion 21T of the wall 21W to the second lower surface 22C due to the gap 22G of the heat insulating material. For this reason, the rise in the temperature of the heat insulating block 22 when the temperature of the heater 21 is raised is suppressed. Further, the amount of heat taken off when the heater 21 generates heat is also reduced, and the heat can be effectively transmitted to the attachment tool 20 side, and thus the electronic component C, which is sucked and held on the lower surface of the heater 21 at the time of thermocompression bonding. There is also the effect of saying.

  Further, even if the shapes of the grooves 21U vary, the upper part of each groove 21U is connected to the gap 22G, and the heat of the groove 21U having a low cooling effect propagates to the surroundings, so that the cooling effect between the grooves 21U varies. Is improved.

  By the way, the interval HG of the gap formed by the step between the lower surface 22S of the heat insulating block 22 and the second lower surface 22C is determined as follows. That is, the lower limit is a value at which the upper portion 21T of the wall 21W does not contact the second lower surface of the heat insulating block 22 even when the heater 21 and the heat insulating block 22 are deformed due to the temperature rise and cooling of the heater 21. The upper limit is determined by the ratio of the sectional area of the gap 22G to the sectional area of the groove 21U from the viewpoint of cooling efficiency and the like.

  That is, as the lower limit, the interval HG satisfies the following expression (1) so that the upper portion 21T does not contact the second lower surface 22C of the heat insulating block 22 even if the wall 21W thermally expands to the maximum. Here, α is the coefficient of thermal expansion of the material constituting the heater 21, and ΔT is the temperature difference between when the temperature of the heater 21 is raised and when it is cooled.

HG> α × ΔT × HU (1)
On the other hand, as the upper limit, if the cooling area / channel volume in terms of the cooling efficiency is to be higher than the method without the gap 22G, the following equation (2) must be satisfied. 3) is desirable.

(2HU + WU) / (HU × WU) ≦ WT / (HG × (WU + WT)) (2)
HG ≦ WT × HU × WU / ((WU + WT) × (2HU + WU)) (3)
However, the viewpoint of the heat insulating property between the heater 21 and the heat insulating block 22 and the effect of reducing the cooling unevenness can be obtained even if the expression (3) is not satisfied. Therefore, as a condition for obtaining the effect of effectively sending the cooling air into the groove 21U, there is no problem as long as the cross-sectional area formed by the gap 22G is equal to the cross-sectional area formed by the groove 21U. That is, it is only necessary to satisfy Expression (5) as the condition of the interval HG from Expression (4).

HG × (WU + WT) ≦ HU × WU (4)
HG ≦ HU × WU / (WU + WT) (5)
Conditions satisfying such conditions differ depending on the shape and arrangement of the groove 21U, but specific numerical values are preferably in the range of 0.3% to 40% of the depth HU of the groove 21U.

  By the way, since the cooling effect can be expected as the number of the grooves 21U in the heater 21 increases, it is desirable to form as many grooves as possible according to the processing accuracy. In addition, since the cooling effect can be expected as the depth HU of the groove 21U is larger, it is desirable to make the depth as deep as possible without hindering the embedding of the heating resistor. Here, increasing the number of the grooves 21U and increasing the depth HU decrease the mechanical strength of the wall 21W, but the upper portion 21T of the wall 21W does not come into contact with the heat insulating block 22 as described above. Therefore, there is no stress. For this reason, the grooves 21U can be formed deeper and deeper than in the prior art, which is effective for improving the cooling effect.

  As described above, by using the bonding head 2 described in the present embodiment, the cooling efficiency of the heater 21 can be improved, and the wall 21W of the heater 21 can be prevented from being scraped or damaged. For this reason, in the mounting apparatus 1 using the bonding head 2 of the present embodiment, the tact time for mounting electronic components can be reduced without adversely affecting the mounting quality.

  Although the example in which the gap 22G is provided in the heat insulating block 22 has been described with reference to FIG. 1, the present invention is not limited to this as long as the upper portion 21T of the wall 21W does not contact the heat insulating block 22. That is, as in another embodiment shown in FIG. 3, a gap 21G may be provided on the upper surface 22S of the heater 21 so that the upper portion 21T of the wall 21W is lower. That is, even when the heater 21 whose three views are shown in FIG. 4 is used and the heat insulating block 22 shown in FIG. Here, the interval between the gaps 21G of the heater 21 is also preferably in the same range as the interval HG of the gap formed by the step between the lower surface 22S and the second lower surface 22C of the heat insulating block 22 shown in FIG.

  Further, the present invention may be applied not only to the bonding head 2 but also to the substrate stage 4 for holding and heating the substrate B side, and it may be used for both the bonding head 2 and the substrate stage 4 to perform heating and cooling from both sides. good. When the electronic component C is minute and the substrate B side has a large volume and the amount of heat from the head side is not sufficiently transmitted, it is effective to heat the substrate B side with a heater. In this case, it is effective to heat the heater from both sides.

DESCRIPTION OF SYMBOLS 1 Mounting device 2 Bonding head 3 Bonding unit 4 Substrate stage 5 Image recognition means 20 Attachment tool 21 Heater 21G Gap 21P Tubular flow path 21S Upper surface of heater 21T Upper part of wall 21U Groove 21W Wall which forms groove 22 Thermal insulation block 22C Thermal insulation block Second lower surface 22D recess 22G gap 22S Lower surface of heat insulating block 22V ventilation hole 23 holder 24 head body B substrate C electronic component AB wall shaved portion BP debris BR damaged wall portion HG gap spacing HU groove depth PW wear powder WT Wall width (thickness)
WU groove width

Claims (3)

A bonding head used for heat compression bonding of electronic components,
An attachment tool that holds the electronic components on the underside,
A heater disposed on top of the attachment tool;
A heat insulating block disposed above the heater,
On the upper surface side of the heater, a plurality of plate-shaped walls formed by providing a plurality of parallel grooves,
A bonding head in which the plate-shaped wall has a gap at an interface with a lower surface of the heat insulating block by lowering an upper portion with respect to an upper surface of the heater. The bonding head according to claim 1, wherein
The gap between the gaps is 0.3% or more and 40% or less of the depth of the groove. A mounting apparatus comprising the bonding head according to claim 1 or 2.

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