JP2012151761A - Surface protection adhesive tape for solid-state imaging device - Google Patents

Abstract

In an image sensor mounting process using a solid-state image pickup device, the present invention heats the image sensor by heating to 170 ° C. or higher in a state where a surface protective adhesive tape is bonded to the light receiving portion side of the image sensor. On the surface of the light receiving part after the adhesive tape is peeled off after reflowing the terminal part to the substrate side and soldering, the adhesive residue on the outer peripheral part of the part where the tape is bonded is greatly reduced.
In a mounting process of a video sensor using a solid-state imaging device, a surface protective pressure-sensitive adhesive tape used on a light receiving part side of the video sensor, the cut end of the pressure-sensitive adhesive tape in a pressure-sensitive adhesive tape comprising a base material and a pressure-sensitive adhesive layer The adhesive tape for surface protection is characterized in that the adhesive burr of the portion has a height from the surface of the pressure-sensitive adhesive layer of 3 μm or less.
[Selection] Figure 1

Description

  The present invention relates to a mounting process of a video sensor using a solid-state imaging device.

In recent years, image sensors using solid-state imaging devices have been widely used in digital cameras, video cameras, and the like.
In the manufacturing process including mounting of the image sensor on the substrate side, scratches on the surface of the image sensor and adhesion of dust are highly likely to directly affect imaging.
Therefore, as shown in Patent Documents 1 to 3, a technique is employed in which the adhesive tape is used as a surface protection tape and is attached to the light receiving portion side of the image sensor to prevent scratches and dust from being attached in the mounting and manufacturing process. .

On the other hand, when mounting a video sensor on a substrate or the like, until now, a method of soldering and mounting the terminal portions one by one using a soldering iron has been used. A method of connecting and mounting at a time by using a solder reflow furnace in an aligned state is often used.
Since the solder reflow furnace needs to be heated to a temperature higher than the melting point of the solder at least, the heating reflow is carried out with the adhesive tape for the above-mentioned protection attached, and the adhesive tape is also heated to a high temperature. Is done.

As described above, the adhesive tape heated to a high temperature has a problem of adhesive residue derived from the adhesive on the surface from which the tape has been peeled due to deterioration of the adhesive due to heat. To solve this problem, a certain effect can be obtained by using a silicone adhesive with high heat resistance for the adhesive or an acrylic adhesive that can prevent contamination of the adhesive even if it is thermally crosslinked by high crosslinking. It is getting to be.
However, although the adhesive residue in the pasting surface has been improved, the adhesive residue on the outer peripheral portion of the tape is still generated, and it is desired to improve the adhesive residue in this portion.

JP 2008-201899 A JP 2006-332419 A JP 2006-077072 A

  Therefore, the present invention provides a video sensor mounting process using a solid-state imaging device by heating to 170 ° C. or higher with a surface protective adhesive tape bonded to the light receiving portion side of the video sensor. A protective pressure-sensitive adhesive tape characterized in that the adhesive residue on the surface of the light-receiving part after the adhesive tape has been peeled off after reflowing the terminal part and the solder connection, greatly reduces the adhesive residue on the outer periphery of the part where the tape is bonded. It is to provide.

As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by using the following adhesive tape, and have completed the present invention.
In the mounting process of the image sensor using the solid-state imaging device, the adhesive tape for surface protection used on the light receiving portion side of the image sensor, the cut end portion of the adhesive tape in the adhesive tape composed of a base material such as polyimide and an adhesive layer The adhesive burr for the surface protection has a height from the surface of the pressure-sensitive adhesive layer of 3 μm or less, and a mounting method for the image sensor using the pressure-sensitive adhesive tape for surface protection.

When the adhesive tape is cut into a required shape, the base material and the adhesive on the cut surface are deformed by the stress of cutting. As a result of observing many adhesive tapes cut by various methods, it was found that the amount of deformation and the shape of the deformation differ depending on the cutting method and cutting direction. In addition, after using these many cut adhesive tapes and pasting them to the glass used for video sensors, heating them at 260 ° C reflow, waiting for them to cool naturally to room temperature, and then peeling them off. It was found that there was a great difference in the adhesive residue on the glass at the outer periphery of the tape depending on the shape of the tape cut surface and the amount of deformation.
That is, it has been confirmed that the adhesive residue can be significantly reduced when the adhesive burr at the cut end of the adhesive tape in the adhesive tape composed of the base material and the adhesive layer is 3 μm or less in height from the adhesive surface side. For this reason, foreign matter due to adhesive residue does not adhere to the surface of the image sensor, and the captured image does not deteriorate. In addition, when the adhesive layer is deformed from the adhesive surface side to the base material side, it can be considered that the adhesive layer is deformed to the minus side when the adhesive surface is used as a reference, so that it is included in a height of 3 μm or less. To do.

Sectional drawing of the adhesive tape of this invention. The figure which shows the direction of the burr | flash in the case of showing the deformation amount with plus. The figure which shows the direction of the burr | flash in the case of showing the deformation amount by minus.

Embodiments of the present invention will be described below.
The mounting method of the image sensor of the present invention is a state in which an adhesive tape using a polyimide film as a constituent material of the base material is bonded to the light receiving part side of the image sensor in the mounting process of the image sensor using the solid-state imaging device. Then, the terminal portion of the video sensor is reflowed by solder connection with the substrate side.

  The image sensor using the solid-state imaging device here is an image sensor obtained by packaging a solid-state imaging device generally called CCD (Charge Coupled Device) or CMOS (Complementary MOS) using a transparent resin or a glass material. is there.

The light receiving part side of the image sensor means the surface side of the sensor that receives the image, and a general image sensor may be covered with a transparent resin or a glass cover to protect the imaging device. In most cases, this includes substantially bonding the adhesive tape to the surface of these transparent resins or cover glass.
Moreover, as for the surface, at least a portion corresponding to the light receiving portion may be protected, but other portions may be covered for protection.

The pressure-sensitive adhesive tape of the present invention is basically formed from a tape base material 1 and a pressure-sensitive adhesive layer 2 provided on one side of the tape base material 1, but as shown in FIG. On the other hand, the separator 3 may be bonded.
In other words, by attaching a release film with a release treatment on at least one surface to a tape substrate via an adhesive layer, the adhesive layer is protected and foreign matter does not adhere to the adhesive layer. The sensor surface can be protected.
After mounting the image sensor protected by the adhesive tape through a process such as reflow, the adhesive tape is peeled off from the image sensor at an arbitrary stage. By this process, generation of adhesive residue from the adhesive tape on the surface of the image sensor can be reduced, and the image sensor can be protected.

  In the base material layer used in the present invention, the type of base material is not particularly limited, but a heat-resistant base material is suitable as the adhesive tape to be bonded to these. For example, plastic substrates such as polyester, polyamide, polyphenylene sulfide, polyetherimide, polyimide, polyamideimide, polysulfone, polyetherketone and the like, porous substrates, glass substrates such as glassine paper, fine paper, Japanese paper, cellulose, polyamide It is preferably selected from nonwoven fabric base materials such as polyester and aramid, metal film base materials such as aluminum foil, SUS foil, and Ni foil. In particular, a polyimide having heat resistance sufficiently withstanding reflow and a relatively small linear expansion coefficient is more preferable.

The base material may be a polyimide film alone, but may be a base material in which at least one polyimide film layer is laminated and a film containing a polyimide material as a raw material. Examples of polyimide films that can be used include Toray DuPont and Kapton 100H.
Moreover, what performs arbitrary surface treatment and extending | stretching processing, or a plasticizer and an additive may be contained.

  As thickness of a base material, it is 10-200 micrometers normally, Preferably it is 15-150 micrometers, More preferably, it is 20-100 micrometers. If the thickness is 10 μm or more, the substrate is sufficiently rigid so that handling is easy, and further, it is possible to prevent the occurrence of a problem that the tape is torn when the tape is peeled off from the image sensor after reflow. Moreover, if it is 200 micrometers or less, it will become advantageous in terms of cost.

The pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as it has heat resistance.
Specifically, for example, various pressure-sensitive adhesives such as an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, and an epoxy pressure-sensitive adhesive capable of bonding the image sensor to the tape at room temperature are used. In addition, when the chip is bonded to the sheet, it may be bonded by heating, not at normal temperature, so that a heat-resistant thermoplastic polyimide resin, polyetherimide resin, polyetheramide resin, polyamideimide resin, Various adhesives such as polyether amide imide resins, block copolymers such as styrene-ethylene butylene-styrene (SEBS), styrene-butadiene-styrene (SBS), styrene-isobutadiene-styrene (SIS), and fluorine compound-containing resins Used.

  Among these, from the viewpoints of heat resistance, cost, and stickability at normal temperature, preferably, a silicone pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive that has been crosslinked to improve heat resistance, more preferably a silicone pressure-sensitive adhesive. . Moreover, you may mix a silicone resin and an acrylic resin.

  The silicone-based pressure-sensitive adhesive generally contains dimethylpolysiloxane and includes a peroxide-curing type silicone-based pressure-sensitive adhesive and an addition reaction type silicone-based pressure-sensitive adhesive. Peroxide curable silicone pressure-sensitive adhesives are used with increased cohesive strength by a curing (crosslinking) reaction using peroxide as a catalyst. The addition reaction curable silicone-based pressure-sensitive adhesive is used with increased cohesive force by a hydrosilylation crosslinking reaction using a metal catalyst. In the present invention, it is possible to use either a peroxide curable silicone pressure-sensitive adhesive or an addition reaction type silicone pressure-sensitive adhesive on the condition that it has heat resistance capable of withstanding solder reflow.

  In the present invention, commercially available products can be used for the peroxide curable silicone pressure-sensitive adhesive and the addition reaction type silicone pressure-sensitive adhesive, respectively. Examples of commercially available peroxide-curing silicone pressure-sensitive adhesives include SH4280 manufactured by Toray Dow Corning Silicone, KR-12 manufactured by Shin-Etsu Chemical Co., Ltd., and the like. Examples of commercially available addition reaction type silicone pressure-sensitive adhesives include SD4570 and SD-4601FC manufactured by Toray Dow Corning Silicone, X-40-3004A manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

  Examples of the peroxide used as a curing agent (crosslinking agent) for the peroxide-curing silicone pressure-sensitive adhesive include benzoyl peroxide, dicumyl peroxide, p-chlorobenzoyl peroxide, peroxide-2, 4-Dichlorobenzoyl, di-t-butyl peroxide, etc. are mentioned. Any of these peroxides may be used alone, or two or more thereof may be used in combination, and the amount used is not particularly limited, but is 0.5 to 2 per 100 parts by weight of the silicone-based pressure-sensitive adhesive. About 5 parts by weight is preferred. Moreover, a chloroplatinic acid catalyst is suitable as a metal catalyst used as a curing agent (crosslinking agent) for the addition reaction type silicone pressure-sensitive adhesive. The amount of the metal catalyst used is not particularly limited, but is preferably about 0.5 to 1.5 parts by weight per 100 parts by weight of the silicone-based pressure-sensitive adhesive.

  The peroxide curable silicone pressure-sensitive adhesive and the addition reaction type silicone pressure-sensitive adhesive are usually marketed in the form of a liquid (hereinafter also referred to as pressure-sensitive adhesive liquid) in which the pressure-sensitive adhesive is dissolved or dispersed in an appropriate solvent. ing. When such an adhesive is used, a coating liquid obtained by adding a curing agent (peroxide, metal catalyst) to the adhesive liquid is prepared, and this is applied to a substrate to obtain a coating film. The pressure-sensitive adhesive layer is formed by heat-crosslinking (curing) the coated film. More specifically, a silicone rubber-like material generated by heating the coating film stabilizes the shape of the film, whereby the pressure-sensitive adhesive layer is formed. To form a laminated structure based on the content distribution of toluene-soluble polydimethylsiloxane when forming the pressure-sensitive adhesive layer as in the pressure-sensitive adhesive tape of the present invention, a plurality of concentrations of toluene-soluble polydimethylsiloxane are different. It is convenient to prepare a coating solution of, and sequentially apply and cure.

As an acrylic adhesive, what consists of an acrylic copolymer obtained from copolymerization of the monomer which contains an alkyl (meth) acrylate at least is mentioned, for example. In addition, in this specification, alkyl (meth) acrylate means alkyl acrylate and / or alkyl methacrylate.
Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl ( Examples include meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, and dodecyl (meth) acrylate. Among them, copolymerization of acrylic acid monomer and 2-ethylhexyl (meth) acrylate monomer, copolymerization of methyl and / or ethyl (meth) acrylate, acrylic acid monomer and 2-ethylhexyl (meth) acrylate monomer preferable.

The pressure-sensitive adhesive layer may contain a crosslinking agent as required.
Examples of such a crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine compound, a chelate crosslinking agent, and the like.
Although content of a crosslinking agent is not specifically limited, For example, when using an acrylic adhesive, 0.1-20 weight part is preferable with respect to 100 weight part of acrylic polymers, and 0.5-10 weight part is More preferred.

The pressure-sensitive adhesive layer is usually used in the field such as plasticizers, pigments, dyes, anti-aging agents, antistatic agents, and fillers added to improve the physical properties (eg, elastic modulus) of the pressure-sensitive adhesive layer. Various additives may be added. The content is not particularly limited as long as appropriate tackiness is not impaired.
The pressure-sensitive adhesive tape used in the present invention is obtained by providing a pressure-sensitive adhesive layer having a thickness of usually 1 to 50 μm on a substrate.

The adhesive tape manufactured as described above is processed into a predetermined size and then used on the light receiving portion side of the video sensor in the mounting process of the video sensor using the solid-state imaging device.
In this processing, cutting with a blade or punching with a die is generally performed, and glue burrs are generated on the cut surface depending on the method and conditions during processing. The glue burr here means a state where the cut surface is deformed by processing or the like, and when the adhesive layer surface is used as a reference, the direction that warps to the glue surface side is indicated by plus, and the direction opposite to the glue surface side The state of warping is represented by minus. That is, the state of FIG. 2 is positive and the amount of deformation is shown, and the state of FIG. 3 is negative and is the amount of deformation.

  As a result of observing many adhesive tapes cut by various methods, it was found that the amount of deformation and the shape of the deformation differ depending on the cutting method and cutting direction. In addition, after using these many cut adhesive tapes and pasting them to the glass used for video sensors, heating them at 260 ° C reflow, waiting for them to cool naturally to room temperature, and then peeling them off. It was found that there was a great difference in the adhesive residue on the glass at the outer periphery of the tape depending on the shape of the tape cut surface and the amount of deformation.

That is, it has been confirmed that the adhesive residue can be significantly reduced when the adhesive burr at the cut end of the adhesive tape in the adhesive tape composed of the base material and the adhesive layer is 3 μm or less in height from the adhesive surface side. In addition, when the adhesive layer is deformed from the adhesive surface side to the base material side, it can be considered that the adhesive layer is deformed to the minus side when the adhesive surface is used as a reference, so that it is included in a height of 3 μm or less. To do.
If the adhesive burr height of the adhesive tape for surface protection of the present invention is 3 μm or less, even if the light receiving part side of the image sensor is protected, the adhesive residue on the surface of the image sensor after peeling after protection can be reduced. The possibility that the image captured by the image sensor deteriorates and becomes defective can also be reduced.

If the height of the glue burr is large on the plus side, the glue burr part will stick first when the tape is attached to the adherend. It seems to be affected. For this reason, it is considered that the glue burr part is partially broken by the stress due to the pressure. Further, the adhesive burr is firmly bonded to the adherend by sufficient pressure, and the adhesive strength to the adherend is increased by reflow heating. As a result, it is considered that adhesive residue is likely to occur at the end of the tape when the tape is peeled off.
For this reason, the adhesive residue in a tape edge part can be decreased by making the height of a glue burr as low as possible, or making it minus.

  The processing method such as cutting and punching is not particularly limited, but generally, the blade edge is sharp and has an acute angle, and the faster the cutting speed, the less the adhesive burr at the time of cutting. Moreover, there is a tendency that there are fewer glue burrs when the blade when cutting the adhesive tape is cut from the substrate surface. In the case of punching, there is a tendency that there are few glue burrs when the speed of punching is increased.

Example 1
A polyimide film (Toray DuPont, Kapton 100H (trade name)) having a thickness of 25 μm was used as a base material layer. On the other hand, 3 parts of a platinum catalyst and toluene were added and dispersed uniformly, and then coated and dried to prepare an adhesive tape having an adhesive layer with a thickness of about 6 μm. ) Was treated with fluorosilicone.
This adhesive tape was cut from the back of the substrate at a blade angle of about 45 ° and a cutting speed of about 30 M / min using a trimming knife. Note that the blade angle 0 ° from the back surface of the base material is an angle when the blade is placed in parallel on the back surface of the base material and punched, and the blade angle 45 ° is inclined by 45 ° with respect to the back surface of the base material. It is the angle when cutting in the direction of cutting.

Example 2
The adhesive tape produced in Example 1 was cut at a blade angle of 0 ° and a cutting speed of 2 M / sec from the back of the substrate, assuming a punching process using a trimming knife.

Comparative Example 1
The pressure-sensitive adhesive tape produced in Example 1 was cut from the pressure-sensitive adhesive surface at a blade angle of about 45 ° and a cutting speed of about 30 M / min using a trimming knife.

Comparative Example 2
The pressure-sensitive adhesive tape produced in Example 1 was cut from the pressure-sensitive adhesive surface at a blade angle of about 45 ° and a cutting speed of about 10 M / min using an NT cutter.

Comparative Example 3
The pressure-sensitive adhesive tape produced in Example 1 was cut at a blade angle of 0 ° and a cutting speed of 0.1 M / sec.

Evaluation method Paste burr (μm)
The produced sample was observed with a SEM (scanning electron microscope) from the cross section and the 45 ° direction, and the height of the glue burr was obtained. Note that, when the height is on the glue surface side (FIG. 2), the actual height is shown, but when the height is on the substrate side (FIG. 3), 0 or less (minus) It was.

Residue of cut part After pasting the sample on untreated glass (elementary glass), after reflow heating at 260 ° C using NORITAKE heating equipment (model number CLF-104C), leaving it to cool at room temperature for 30 minutes, tape It peeled off and the cutting part adhesive residue was observed with the optical microscope.
In addition, the cutting part has shown the part cut | disconnected by the knife for trimming and NT cutter in Examples 1-2 and Comparative Examples 1-3, respectively.
Further, with respect to the evaluation criteria for the adhesive residue, with Comparative Example 1 as a reference, the case where the adhesive residual area is visually 25% to 50% less is ◯, the case where it is less than 50% is ◎, and conversely 25% to 50% is more The case was judged as Δ, and the case where it was more than 50% was judged as ×.
In Comparative Example 1, the adhesive residue could be clearly confirmed, and it was also confirmed that the adhesive residue remaining at the cut portion increased as the height of the glue burr increased.
In Example 1 and Example 2, although there was adhesive residue at the cut portion, there were very few adhesive burrs, and it was confirmed that the adhesive residue was reduced by reducing the height of the adhesive burrs.

DESCRIPTION OF SYMBOLS 1 ... Tape base material 2 ... Adhesive layer 3 ... Separator h ... Paste burr height

Claims (4)

  In a mounting process of a video sensor using a solid-state imaging device, an adhesive tape for surface protection used on the light receiving part side of the video sensor, the adhesive burr at the cut end of the adhesive tape in the adhesive tape comprising a base material and an adhesive layer Is a pressure-sensitive adhesive tape for surface protection, wherein the height from the surface of the pressure-sensitive adhesive layer is 3 μm or less.   The surface-protective pressure-sensitive adhesive tape according to claim 1, wherein polyimide is used as a base material of the pressure-sensitive adhesive tape.   In the mounting process of the image sensor using the solid-state imaging device, the glue burr at the cut end portion of the adhesive tape in the adhesive tape composed of the base material and the adhesive layer is 3 μm or less higher than the adhesive surface side on the light receiving portion side of the image sensor. A method of mounting an image sensor, comprising: reflowing the terminal portion of the image sensor by soldering to the substrate side by heating to 170 ° C. or higher while the adhesive tape is attached.   4. The video sensor mounting method according to claim 3, wherein polyimide is used as a base material of the adhesive tape.