JP2021163774A - Crimping head, mounting device, and mounting method using this - Google Patents

Abstract

To provide a crimping head that can perform mounting with excellent bonding quality under each condition even when the material of a substrate is different when an electronic component such as a semiconductor chip is temporarily fixed to a substrate via a thermosetting adhesive in a laminated state to perform thermocompression bonding, a mounting device using this, and a mounting method.SOLUTION: A crimping head for mounting an electronic component on a substrate includes an attachment including a head body with a built-in heater, a pressing member that presses an electronic component mounted on the lower part of the head body, and an elastic member interposed between the head body and the pressing member, and a laminate of a material different from that of the pressing member is provided on the surface of the pressing member facing the electronic component, and there are also provided a mounting device and a mounting method using the crimping head.SELECTED DRAWING: Figure 1

Description

The present invention relates to a crimping head for mounting electronic components such as semiconductor chips in multiple stages on various substrates such as a silicon substrate, a glass epoxy substrate, and a glass substrate, and a mounting apparatus and mounting method using the same.

Flip chip mounting is well known as a method for mounting electronic components such as semiconductor chips on a substrate. In the flip chip mounting, the bumps formed on the semiconductor chip are aligned with the electrode pads of the circuit board and then thermocompression bonded.

In conventional flip chip mounting, it is common to melt bumps mainly made of solder by thermocompression bonding and join them to the electrode pads of the substrate, and then inject a liquid sealing resin adhesive into the gap between the semiconductor chip and the substrate to cure them. It was a target. On the other hand, these days, a non-conductive film (Non Conducive Film, hereinafter referred to as "NCF") containing a thermosetting adhesive as a main component is temporarily fixed to a substrate on a bump surface of a semiconductor chip. A method of (temporary crimping) and then thermocompression bonding (main crimping) (for example, Patent Document 1) is attracting attention.

In the method of temporarily fixing using NCF and then thermocompression bonding, it is also possible to temporarily fix the semiconductor chip C on the entire surface of the substrate S (FIG. 6 (a)) and then thermocompression bond. ), It is possible to thermocompression-bond a plurality of semiconductor chips C at the same time.

Further, if a semiconductor chip C having an electrode on the opposite side of the bump surface by a through electrode is used, as shown in FIG. 7A, the semiconductor chip C is temporarily fixed via the NCF in a multi-stage laminated state, and then FIG. It can also be thermocompression bonded as in 7 (b), and so-called 3D mounting can be performed with high efficiency.

Japanese Unexamined Patent Publication No. 2016-9850

In mounting using NCF, the relationship between the curing state of NCF and the melting timing of bumps is important, and it is necessary to make the NCF temperature rise curve at the time of thermocompression bonding appropriate. That is, if the bumps are melted when the NCF is not sufficiently cured, the bumps are crushed, and when the bump melting temperature is reached after the NCF is cured, the bumps and the electrodes of the substrate (or semiconductor chip) become difficult to approach and the bonding is poor. It becomes.

Therefore, the temperature of the heater 31 built in the head body 3 for heating the attachment 40 in FIGS. 6 and 7 and the temperature of the heater 31 so as to obtain an NCF temperature rising curve in which the bumps are melted in a state where the NCF is appropriately cured It is necessary to set the temperature of the substrate stage 2 appropriately. In particular, when the semiconductor chips C are stacked in multiple stages as shown in FIG. 7, it is necessary to make settings so that the NCF temperature rise curves of all the semiconductor chips stacked in multiple stages are within the permissible range.

However, it was found that even if the temperatures of the heater 31 and the substrate stage 2 were set, the temperature rise curve changed significantly depending on the type of the substrate S. That is, when the substrate is the substrate B under the same conditions as when the appropriate NCF temperature rise curve as shown in the substrate A of FIG. 8 is obtained, the NCF is cured by the time the bump melting temperature Tm is reached and the NCF is joined. A defect has occurred. This is caused by the difference in thermal conductivity between the materials of the substrate A and the substrate B, and the temperature rise of NCF is faster when the substrate B having a low thermal conductivity is used than to the substrate A having a high thermal conductivity.

Further, the difference in the NCF temperature rise curve between the semiconductor chips stacked in multiple stages is suppressed in the substrate A, whereas it is widened in the substrate B. Therefore, in the substrate B, it is difficult to set the NCF temperature rise curve in all the semiconductor chips stacked in multiple stages within the allowable range.

The present invention has been made in view of the above problems, and when electronic components such as semiconductor chips are temporarily fixed to a substrate in a laminated state via a heat-curable adhesive and then thermocompression bonded, the material of the substrate is used. Provided are a crimping head capable of mounting with excellent bonding quality under each condition, a mounting device using the crimping head, and a mounting method.

In order to solve the above problems, the invention according to claim 1 is
A crimping head that mounts electronic components on a board.
An attachment having a head body having a built-in heater, a pressing member for pressing an electronic component mounted on the lower portion of the head body, and an elastic member interposed between the head body and the pressing member is provided.
A crimping head provided with a laminate of a material different from that of the pressing member on a surface of the pressing member facing the electronic component.

The invention according to claim 2 is a crimping head for mounting an electronic component on a substrate.
An attachment having a head body having a built-in heater, a pressing member for pressing an electronic component mounted on the lower portion of the head body, and an elastic member interposed between the head body and the pressing member is provided.
A crimping head for arranging a sheet material made of a material different from that of the pressing member between the pressing member and the electronic component.
The invention according to claim 3 is the crimping head according to claim 1 or 2.
A crimping head having a thermal conductivity of a material different from that of the pressing member, which is 1/30 or less of that of the pressing member.

The invention according to claim 4 is the crimping head according to claim 3.
The pressing member is a metal, and the material different from the pressing member is a crimping head made of glass, ceramics, or a heat-resistant resin.

The invention according to claim 5 is the crimping head according to any one of claims 1 to 4.
It is a crimping head capable of mounting a plurality of electronic components at the same time.

The invention according to claim 6 includes the crimping head according to any one of claims 1 to 5.
A pressurizing means that allows the crimping head to move up and down and applies a pressing force toward the substrate.
It is a mounting device including a substrate stage that supports the pressure surface of the attachment from the substrate side.

The invention according to claim 7 is the mounting device according to claim 6.
It is a mounting device having a configuration in which an attachment protective film is arranged between the crimping head and the substrate in parallel with the substrate.

The invention according to claim 8 uses the mounting apparatus according to claim 6 or 7.
This is a mounting method in which the electronic component having a thermosetting adhesive layer formed on an electrode surface is mounted on the substrate.

The invention according to claim 9 is the mounting method according to claim 8.
This is a mounting method in which the material and / and the thickness of a material different from that of the pressing member are changed according to the type of the substrate.

According to the present invention, when an electronic component such as a semiconductor chip is temporarily fixed to a substrate via a thermosetting adhesive in a laminated state and then thermocompression bonded, even if the material of the substrate is different, the bonding quality is different under each condition. It has become possible to implement excellently.

A state in which a semiconductor chip temporarily fixed in a multi-stage laminated state is mounted using a crimping head according to an embodiment of the present invention is described, and is a diagram showing (a) a state after alignment, and (b). It is a figure which shows the state during thermocompression bonding. It is a figure which shows the modification of the crimping head which concerns on embodiment of this invention. It is a temperature rise curve for demonstrating the effect of the crimping head which concerns on embodiment of this invention. It is a figure which shows the example which realizes this invention with the structure different from the embodiment. It is a figure explaining the example which realized the effect similar to this invention by the method different from the embodiment. A crimping head capable of mounting a plurality of semiconductor chips on a substrate will be described, (a) is a diagram showing a state after alignment, and (b) is a diagram showing a state during thermocompression bonding. A state in which a semiconductor chip temporarily fixed in a multi-stage laminated state is mounted using a crimping head capable of mounting a plurality of semiconductor chips on a substrate is described, and (a) is a diagram showing a state after alignment. (B) It is a figure which shows the state during thermocompression bonding. It is a figure which shows the example which the temperature rise curve is different if the substrate is different even if the same crimping head is used.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example in which a semiconductor chip C in a laminated state is mounted on a substrate S by using the crimping head 1 according to the embodiment of the present invention. In FIG. 1A, the semiconductor chip C, which is an electronic component, is temporarily fixed on the substrate S in a multi-stage laminated state via an uncured NCF. Here, NCF is a non-conductive fill in which insulating fine particles are dispersed mainly by a thermosetting adhesive such as epoxy. Further, although not shown, an electrode pad is provided at a position facing the bump of the semiconductor chip C. Although FIG. 1 shows an example in which semiconductor chips C are laminated in four stages, the number of laminated stages is not limited to this, and may be less than this, but the effect of the present invention is that four or more stages are laminated. It is beneficial if you do.

FIG. 1A shows a state in which the crimping head 1 and the semiconductor chip C temporarily fixed to the substrate S (in a multi-stage laminated state) are aligned with each other.

The crimping head 1 is composed of a head body 3 and an attachment 4. In the example of FIG. 1, the head main body 3 has a head housing 30 and a heater 31, and the attachment 4 has an elastic member 41, a pressing member 42, a support holder 43, and a laminated body 44.

The crimping head 1 is moved up and down by a pressurizing means (not shown) and is driven so as to apply a predetermined pressing force to the semiconductor chip C.

The crimping head 1 is for simultaneously thermocompression-bonding a plurality of semiconductor chips C on the substrate S, and in order to cope with the thickness variation of the semiconductor chip C and the height variation of the bump B, the elasticity according to the number of simultaneous pressings. It has a member 41, a pressing member 42, and a laminated body 44, and an elastic member 41 made of heat-resistant rubber or the like is responsible for absorbing height variations during pressing.

At the time of thermocompression bonding, the heat generated by the heater 31 built in the head body 3 is transferred to the laminated body 44 via the head housing 31, the elastic member 41, and the pressing member 42. Here, since the material of the elastic member 41 generally has low thermal conductivity, a material having high heat conductivity is used for the pressing member 42. Specific examples thereof include aluminum and copper, but the selection is not limited to these, and may be selected in consideration of thermal conductivity, workability, dimensional stability, price, and the like.

The support holder 43 suppresses the inclination of the pressure surface caused by the deformation of the elastic member 41 to maintain parallelism.

The laminated body 44 is a component of the present invention, not in the structure shown in FIGS. 6 and 7. The laminated body 44 constitutes the pressure surface of the crimping head 1, and plays a role of regulating the heat flow through the pressing member 42. Therefore, the material of the laminated body 44 needs to have a thermal conductivity smaller than that of the pressing member 42, and is preferably 1/30 or less in consideration of reducing the thickness. Specific materials include glass, ceramics, and heat-resistant resins.

The substrate stage 2 supports the range pressurized by the crimping head 1 from the substrate S side, and may have a built-in heater.

By the way, when the attachment 4 pressurizes the semiconductor chip C while directly heating it, the heated and softened NCF may protrude to the surroundings and stain the pressurized surface of the attachment 4. If the pressurized surface of the attachment 4 becomes dirty, the pressurized surface may be uneven or inclined, which may cause inconvenience during the next and subsequent pressurization. Therefore, the attachment protective film 5 is used to prevent the NCF from adhering to the surface of the attachment 4. The attachment protective film 5 is arranged parallel to the pressure surface, and is sequentially conveyed by a transfer mechanism (not shown).

The attachment protective film 5 is preferably a fluorine film because of its heat resistance and releasability to NCF. Further, the thickness of the attachment protective film must have a minimum thickness that does not break during transportation and thermocompression bonding, and specifically, it is 20 μm or more.

The above-mentioned mechanism for supplying the crimping head 1, the substrate stage 2, the attachment protective film 5, and the pressurizing means for driving the crimping head 1 are components of the mounting device.

FIG. 1B shows a state in which thermocompression bonding is performed by the crimping tool 1 in the configuration of the mounting apparatus shown in FIG. 1A. In FIG. 1B, T1 shows the measured temperature of the semiconductor chip C in the first stage from the substrate S, and T4 shows the measured temperature of the semiconductor chip C in the fourth stage. Here, the measured temperature of each semiconductor chip C is substantially equal to the NCF temperature of each semiconductor chip C.

By the way, in FIG. 1, a constant heater having a constant temperature is used as the heater 31, and a silicon substrate is used as the substrate S under the optimized conditions. FIG. 3 is a graph showing the measured temperature of each semiconductor chip C when a glass epoxy substrate is used as the substrate S under such conditions.

In FIG. 3, T1A and T4A show T1 and T4 when the attachment 40 having the conventional configuration without the laminated body 44 is used, and the time required to reach the melting temperature Tm of the bump is short. The bump is crushed. Further, there is a difference in the curves of T1A and T4A, and there is also a difference in the NCF temperature rise curve.

On the other hand, in FIG. 3, T1B and T4B show T1 and T4 when glass having a thickness of 880 μm is used as the laminated body 44. In T1B and T4B, the difference in curve is smaller than that of T1A and T4A, and the time from the start of thermocompression bonding to the bump melting temperature Tm (about T1A and T4A). It was longer (compared to 2 seconds), about 4.5 seconds. This is almost the same as when a silicon substrate is used as the substrate S, and all of the first-stage semiconductor chip C to the fourth-stage semiconductor chip C have good bonding without bump crushing or poor connection. rice field.

Further, in FIG. 3, T1C and T4C show T1 and T4 when a fluororesin having a thickness of 300 μm is used as the laminate 44. Although the temperature rise curves of T1C and T4C are different from those of T1B and T4B, the time from the start of thermocompression bonding to the bump melting temperature Tm is about 4.5 seconds. As a result, good bonding was obtained for all of the first-stage semiconductor chip C to the fourth-stage semiconductor chip C without bump crushing or poor connection.

As described above, by providing a laminate of a material different from the pressing member of the attachment on the pressure surface of the conventional attachment, even if the type of the substrate S is different, the multi-stage semiconductor without changing the conditions such as the heater temperature. It becomes possible to join the chips C without variation in quality.

When the laminated body is provided on the pressing member, a heat-resistant adhesive can be used, but it is necessary to select it in consideration of not only excellent adhesive strength but also long-term durability.

When a fluororesin is used as the laminate 44 in the embodiment of FIG. 1, the flexibility of the fluororesin can be utilized. Therefore, instead of providing the laminate 44 individually for each pressing member 42, the modified example of FIG. 2 is shown. A sheet material 45 made of a material different from that of the pressing member may be arranged so as to cover the plurality of pressing members 42. In this case, it is not necessary to laminate the sheet material 45 on the pressing member 42, and the sheet material 45 may be arranged under the pressing member 44 each time thermocompression bonding is performed.

Further, in the examples of FIGS. 1 and 2, one head body 3 has an attachment 4 for pressurizing a plurality of semiconductor chips C, but as shown in FIG. 4, one head body 3 is used for each attachment 4. As the attachment 4 that pressurizes one semiconductor chip C, a crimping head having a plurality of head bodies 3 may be used.

By the way, when the laminate 44 or the sheet material 45 is a fluororesin, the same material as the attachment protective film 5 is laminated, that is, the thickness is increased. Therefore, FIG. 5 is a verification of the effect of the thickness of the attachment protective film 5. While the temperature curve when the thickness of the attachment protective film 5 (notation in the figure is “insulation sheet”) is 30 μm using the attachment 40 shown in FIGS. 6 and 7, the temperature curve is shown in FIG. 5 (a). Since the temperature curve when the thickness is 360 μm is shown in FIG. 5 (b), it was found that the same tendency as when the thickness of the laminated body 44 is 300 μm appears. However, since the attachment protective film 5 is a consumable item that needs to be transported for each thermocompression bonding, the process cost increases.

1 Crimping head 2 Board stage 3 Head body 4, 40 Attachment
5 Attachment protective film 30 Head housing 31 Heater 41 Elastic member 42 Pressing member 43 Support holder 44 Laminated body 45 Sheet material B Bump C Semiconductor chip S Substrate NCF Thermosetting adhesive film T1 Temperature of the first stage semiconductor chip from the substrate side Temperature of the semiconductor chip in the 4th stage from the T4 substrate side

Claims (9)

A crimping head that mounts electronic components on a board.
The head body with a built-in heater and
A pressing member that presses an electronic component mounted on the lower part of the head body, and
An attachment having an elastic member interposed between the head body and the pressing member is provided.
A crimping head provided with a laminate of a material different from that of the pressing member on a surface of the pressing member facing the electronic component. A crimping head that mounts electronic components on a board.
The head body with a built-in heater and
A pressing member that presses an electronic component mounted on the lower part of the head body, and
An attachment having an elastic member interposed between the head body and the pressing member is provided.
A crimping head for arranging a sheet material made of a material different from that of the pressing member between the pressing member and the electronic component. The crimping head according to claim 1 or 2.
A crimping head in which the thermal conductivity of a material different from that of the pressing member is 1/30 or less of that of the pressing member. The crimping head according to claim 3.
A crimping head in which the pressing member is metal and the material different from the pressing member is glass, ceramics, or heat-resistant resin. The crimping head according to any one of claims 1 to 4.
A crimping head that can mount multiple electronic components at the same time. The crimping head according to any one of claims 1 to 5,
A pressurizing means that allows the crimping head to move up and down and applies a pressing force toward the substrate.
A mounting device including a substrate stage that supports the pressure surface of the attachment from the substrate side. The mounting device according to claim 6.
A mounting device having a configuration in which an attachment protective film is arranged between the crimping head and the substrate in parallel with the substrate. Using the mounting apparatus according to claim 6 or 7.
A mounting method for mounting the electronic component having a thermosetting adhesive layer formed on an electrode surface on the substrate. The mounting method according to claim 8.
A mounting method in which the material and / or thickness of a material different from that of the pressing member is changed according to the type of the substrate.

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