JPH048784A - Heat-resistant tacky agent useful for taping and temporary fixation of electric part - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant tacky agent, standing soldering, in temporary fixation especially using a tacky carrier tape, by making tensile shear peel strength between a taped electric part and a carrier tape in a specific range. CONSTITUTION:The objective tacky agent comprising preferably an acrylic or silicon-based adhesive having a tensile shear peel strength between a taped electronic part and a carrier tape preferably coated with a silicone-based releasing agent adjusted to 2-30gf/mm<2> (most preferably 6-20gf/mm<2>).

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heat-resistant adhesive used for taping and temporary fixing of electronic components, particularly for temporary fixing using adhesive carrier tape, and suitable for soldering. Concerning durable heat-resistant adhesives.

(Prior technology) Small electronic components (
When mounting electronic components (hereinafter simply referred to as "electronic components J") on a printed circuit board, a taping method using automatic equipment is increasingly being adopted. A series of electronic components are then placed on predetermined positions on the board and temporarily fixed using automated equipment.

The adhesive of such conventional adhesive carrier tape is
It was necessary to prevent the adhesive from adhering to the electronic components after they were taped. The reason for this is that when electronic components are mounted on a printed circuit board, they are bonded with an adhesive such as a VV curable adhesive or a thermosetting adhesive. If adhesive remains on electronic components that have been removed from the carrier tape, the adhesive surface will come into contact with the adhesive, making it impossible to form a strong bond, and the high temperatures during soldering may reduce the adhesive strength of the adhesive to the electronic components. This may lead to poor soldering. Therefore, in order to prevent the adhesive from adhering to electronic components, conventional carrier tapes do not have a release layer on the surface to which the adhesive is attached to the base material.

That is, in conventional adhesive carrier tapes, it is necessary that the adhesive does not adhere to electronic components when the electronic components are removed from the tape after being taped. For this reason, ε
IAJ standard 1? In C-1011 electronic component taping method (adhesive type), adhesive taping (TJ321
20, enacted September 1984) is a device in which component adhesive tape coated with adhesive is applied to the back of a support with a hole, and electronic components are taped to the surface of the hole. Note that, practically, after taping the electronic components to the surface of the support, a cover tape is applied to prevent the electronic components from falling off the carrier tape. In addition, the peel strength when peeling the component adhesive tape from the perforated support is defined as the peel strength of the electronic component from the adhesive tape, and the adhesive tape width 6
．． 0.2-0.7N (approximately 20-70gf) for 21
, 165-180° and a peeling rate of 300 mm/min. However, although beer peel strength is indicated, peel strength due to tension and shearing is not specified.

This is probably because the adhesive does not need to be removed once it is attached to the electronic component. This is because conventionally, when an electronic component is removed and placed on a printed circuit board, it is bonded with an adhesive such as a UV curable adhesive or a thermosetting adhesive.

(Problem to be solved by the invention) However, the conventional method of performing taping and adhesive application separately requires more steps, and after the adhesive has hardened, it is difficult to place the tape in the correct position when temporarily bonding. The disadvantage is that the adhesive itself has insufficient properties, such as the fact that electronic components that could not be placed cannot be easily re-peeled.

Therefore, when detaching from the carrier tape, the adhesive is transferred to the bottom of the electronic component 2, and with this heat-resistant adhesive attached to the bottom of the electronic component, it is placed on a printed circuit board for temporary fixing, and then soldered. A method is proposed. In such an adhesive transfer method, it is not necessary to use a UV-curable adhesive or a thermosetting adhesive, but it is necessary to peel the heat-resistant adhesive from the adhesive carrier tape while keeping the heat-resistant adhesive attached to the electronic component. be.

For this reason, it is necessary to provide a release layer on the surface of the adhesive tape coated with a heat-resistant adhesive to facilitate the peeling of the adhesive. In this case, if the peeling is too light, the electronic component will fall off when or after taping the electronic component.

On the other hand, if the peeling force is too large, it will be difficult to easily remove the electronic component from the carrier tape using surface mounting machines currently in use on the market.

As described above, several proposals have already been made for adhesive transfer methods, but none of them can be said to be practical.

For example, in Japanese Utility Model Application Publication No. 58-85397, a double-sided adhesive is interposed between the electronic component and the tape, and the adhesive force of the adhesive layer on the tape side is made smaller than that on the electronic component side, so that the adhesive layer can be easily separated from the tape. The idea of attaching a double-sided adhesive to the bottom of an electronic component has been disclosed, but when soldering, the double-sided adhesive sometimes remains, and soldering is inevitably defective. There is no specific disclosure of a double-sided adhesive body with good adhesive strength, and it cannot be said that it is possible to realize it.

Although a similar idea is disclosed in JP-A-59-23597, there is no specific disclosure regarding the double-sided adhesive (body).

JP-A-59-194498 uses an embossed type of carrier tape, but when the electronic components are removed, the adhesive is transferred to the electronic components and the adhesive is used to fix them to the board. The idea is to do so. However, in this case, compared to previous methods that use double-sided adhesives, the adhesive is simply transferred and the configuration is simpler, but there is no disclosure of the adhesive that makes this possible. However, the content is rather less practical than the conventional one.

Although Japanese Utility Model Application Publication No. 60-41344 discloses providing a release layer on the surface of the tape in order to facilitate release of the adhesive, there is no specific disclosure of the adhesive in this case either.
This also has little practicality.

Thus, the first object of the present invention is to provide a heat-resistant adhesive that makes it possible to transfer the adhesive in an adhesive carrier tape as described above.

A second object of the present invention is to provide a device with a predetermined tensile and shear peeling force that enables an electronic component once attached to a carrier tape by taping to be peeled off from the carrier tape with a heat-resistant adhesive attached thereto. An object of the present invention is to provide a heat-resistant adhesive that can withstand soldering and is used for taping and temporarily fixing electronic components.

(Means for solving the problems) In order to achieve these objectives, from a practical point of view, it is necessary to stably tape electronic components, and to remove them from the carrier tape, it is necessary to It has been found that it is necessary to properly define the adhesive force of the heat-resistant adhesive to the carrier tape, that is, the peel strength, not on the basis of force, but on the basis of tensile force and shear force.

In other words, in the adhesive transfer method that uses an adhesive carrier tape as a carrier for electronic components, it is desired that the tape has the seemingly contradictory properties of stably holding the electronic components and making it easy to remove them. If the adhesion and peeling forces are not within the specified range for each electronic component, problems will occur in practice. Additionally, electronic components come in a variety of shapes, sizes, and weights. In order to tape these onto a carrier tape using an adhesive transfer method, it is necessary that the adhesive force of the heat-resistant adhesive be stabilized, and at the same time, the peeling force between the heat-resistant adhesive and the carrier tape must be within a certain range.

Here, the heat-resistant adhesive that can withstand soldering stably holds the electronic components without falling off the carrier tape when the electronic components are taped, and on the other hand, when the electronic components are removed, they are easily removed from the carrier tape together with the electronic components. To enable peeling, an acrylic or silicone adhesive is used to apply tension or shear peeling force (referred to as tensile/shear peeling force) to the carrier tape.
It was found that 2 to 30gf/a+m" per piece,
We have arrived at the present invention.

Therefore, in the present invention, the tensile/shear peeling force between the electronic component and the carrier tape after taping is 2 to 30 gf/m.
+*'' is a heat-resistant adhesive used for taping and temporary fixing of electronic components.

From another aspect, the present invention has a tensile/shear peeling force of 2 to 30 g between the electronic component and the carrier tape after taping.
This is a taping method using a heat-resistant adhesive used for temporary fixing of electronic components, which has a diameter of f/mm2.

In addition, the adhesive strength between the heat-resistant adhesive and electronic components is as follows:
Normally, it is large enough at 40gf/mm2, and peeling between the bottom of the electronic component and the heat-resistant adhesive does not become a problem.
In the present invention, naturally, the tensile/shear peeling force of the heat-resistant adhesive against the carrier tape is always smaller than that against the electronic component.

According to a preferred embodiment of the present invention, the adhesive is an acrylic or silicone adhesive, and the carrier tape is also coated with a silicone release agent.

(Operation) Next, the present invention will be described in further detail with reference to the accompanying drawings.

In FIG. 1, a tape support 10 is provided with a release layer 12 if necessary. This release layer 12 is provided so that the tensile/shear release force with respect to the adhesive described later is between 2 and 30 gf/mm<2>, and may be provided as necessary. Heat-resistant adhesive 16 is applied at predetermined intervals to the cattle tape 14 prepared in this manner by means such as printing or dispensing, and then the electronic component I8 is placed thereon by an automatic device (not shown). Ru. This is so-called taping.

The electronic components 18 are then removed one by one from the carrier tape on which a large number of electronic components 18 are mounted using an appropriate electronic component mounting means (not shown) and mounted on the circuit board by an automatic device. At this time, the adhesive I6 adhering to the carrier tape 14 is transferred to the bottom surface of the electronic component 18, and this becomes a heat-resistant adhesive for temporary attachment to the circuit board.

In Figure 1, the tensile force in the vertical direction toward the drawing indicates the peeling force due to the tensile force in the vertical direction of the adhesive, and the shearing force in the horizontal direction toward the drawing indicates the peeling force in the horizontal direction of the adhesive. In the present invention, these are collectively referred to as tensile/shearing peeling force, and either one of them, preferably both of them, is 2 to 30 gf/mm.
It needs to be within the range of 2. As already mentioned, this is the peeling force between the carrier tape and the bottom of the electronic component 18, which is usually much larger than this range, so the adhesive separates from the bottom of the electronic component. Never.

As described above, according to the present invention, a heat-resistant adhesive that does not cause any problems even when soldering is applied to the bottom of the electronic component is placed on a printed circuit board, and soldering is performed. There is no need to use adhesives such as UV curable adhesives or thermosetting adhesives.

In addition, because the heat-resistant adhesive is attached to the bottom of the component from the carrier tape and then peeled off and placed on the printed circuit board, in some cases there is a layer on the heat-resistant adhesive coated surface of the carrier tape that can be easily peeled off from the support. In other words, it is necessary to provide a release layer.

In this case, if the peeling is too light, it will fall off when or after taping the electronic component. Furthermore, if the peeling is too heavy, it becomes difficult to easily remove the electronic component using surface mounting machines currently employed in the market.

From these viewpoints, in order to perform stable taping, eliminate the need for cover tape, and enable parts to be removed, the peel strength of the heat-resistant adhesive against tensile and shearing forces is specified.

According to the present invention, the tensile/shear peeling force between the adhesive and the carrier tape is 2 to 30 gf/mm'', preferably 4 to 25 gf/+m2, and most preferably 6 to 20 gf/mm.
/llIC. This tensile/shear peeling force is 2 gf
If it is less than /mm2, the intended purpose will not be achieved;
If f/I2 is exceeded, the adhesive may not be smoothly transferred to the bottom surface of the electronic component when the electronic component is removed.

The viscosity and adhesive strength of heat-resistant adhesives vary depending on the type. Further, the peeling force varies depending on the type of release layer and release agent, coating amount, surface type, coating method, material of the base material, etc. With these combinations, the tensile/shear peeling force between the carrier tape and the carrier tape can be kept within the above-mentioned range, thereby stably holding the electronic component and making it easy to remove it.

Electronic components come in a variety of shapes, sizes, and weights. In order to tape these onto a carrier tape, it is necessary that the heat-resistant pressure-sensitive adhesive has a stable viscosity/adhesive force, and at the same time, it is necessary that the tensile/shear peeling force with the release layer be within a certain range. In addition, the conventional EIAJ standard 1? c-1
011, TJ32120 component adhesive tape, the beer peel strength may meet this standard.

Such tensile shear peeling force can be easily adjusted, for example, by suitably blending one or more of the following tack/adhesion imparting components and heat resistance imparting components.

Of course, the peeling force of the acrylic or silicone adhesive thus obtained can also be adjusted by considering the release layer and other coating conditions as described above.

(1) Silicone-acrylic copolymer resin (e.g. 0-10
0%) (2) Acrylic copolymer resin (e.g. 10-80
%) (3) Urethane or urethane acrylic copolymer resin (e.g. 0-20%) (4) Silicone 4#! (Example: 0-100%) Here, in the adhesive/adhesive with the above composition, the peeling force is determined by the acrylic adhesive which is the adhesive imparting component in both the tensile peeling force and the shear peeling force. It can be decreased by increasing the amount of polymer resin, or it can be increased by increasing the amount of urethane or urethane-acrylic copolymer resin or urethane-acrylic copolymer resin, if such components are low. However, this means that there are cases where the crosslinking agent described below may be used alone.

Furthermore, a crosslinking agent may be added as appropriate.

Of course, as already mentioned, when a release layer is provided on the carrier tape, the above-mentioned release force varies depending on the type of release layer. Typical stripping agents include silicone-based or fluorine-based stripping agents.

After taping in this manner, the electronic component 18 is automatically removed by a surface mounter as required, placed on a predetermined position on the printed circuit board, and temporarily fixed.

When using the adhesive specified in the present invention, temporary fixing is effectively performed, and there are no particular restrictions beyond that, but it is more preferable that the elastic modulus of dynamic viscoelasticity is maintained at the soldering temperature. An adhesive having a density of 10' to 109 dyne/cm2 is used. An adhesive having such characteristics can be easily selected from the above-mentioned adhesives within the scope of the present invention, if necessary.

Next, the present invention will be explained in more detail with reference to Examples.

In this example, resin compositions with various tensile peeling forces and shearing peeling forces were prepared by appropriately changing the blending ratio within the following composition range, and their adhesive strength was evaluated.

(1) Acrylic copolymer resin 40-60% (e.g. HVC-5200 manufactured by Toagosei Chemical Industry Co., Ltd.) (2) Urethane
Acrylic copolymer resin (e.g. H manufactured by ARC Japan)
AP-070) O ~ 10% (3) Nlicon acrylic copolymer resin 40 ~ 60% (Ty manufactured by Nippon Pure Chemical Industries, Ltd.)
-B) In addition, 0.1 to 5.0% of a crosslinking agent was blended.

The tensile peel force and shear peel force could be increased by increasing the blending amounts of the urethane-acrylic copolymer resin and crosslinking agent.

In this example, a release layer was used, and the release layer was a commercially available NRICON system, and this was applied to a paper tape body to construct a carrier tape.

The tensile force and shear force were determined as the peeling force of each resin composition and object obtained, and the handleability and workability were further evaluated. The test results are summarized in Table 1.

(Margin below) Table 1 (Continued from Table 1) (Continued on next page) Measured using a tensile tester and a shear force tester manufactured by Shima Ritsu Seisakusho. All of these peeling forces are those with adhesives.

The ease of handling after 2-permanent taping was examined in the following manner and evaluated on a 4-grade scale.

Taping was performed using a commercially available taping machine, and it was confirmed whether the electronic components did not fall off and were held in the correct position, and whether they could be wound normally onto the take-up reel.

Taping 200 electronic parts Something that won't fall off◎ If less than 2 pieces fall off, △ if less than 5 pieces fall off. 6 or more pieces fall off × The judgment was divided into four stages.

Transparent mounting type The removal work during mounting was investigated as follows.

A commercially available surface mounter was used to automatically place the mount on a printed circuit board, and it was confirmed whether it could be mounted at a specified speed and with high precision.

200 electronic components were placed on a printed circuit board, and the evaluation was divided into 4 grades: ◎ (◎) for those that were all correctly mounted, 0 (for less than 2 parts), 6 (less than 6 parts), and × (for those with less than 6 parts).

(Effects of the Invention) Conventionally, the concept of carrier tape with adhesive has been based on the adhesive transfer method.
As proposed in various publications such as No. 9-23597 and Japanese Unexamined Patent Publication Nos. 59-19449, heat-resistant devices that ensure the taping and removal of electronic components and do not cause any problems even when soldering are performed. However, the present invention has finally put them into practical use, and its practical significance is that it will enable significant rationalization of this field in the future. big.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the usage form of the adhesive according to the present invention. 10; tape support 12: release layer 14: carrier tape 16: heat-resistant adhesive 18: iii child component

Claims (1)

[Claims] A heat-resistant adhesive used for taping and temporary fixing of electronic components, which has a tensile/shear peeling force of 2 to 30 gf/mm^2 with a carrier tape after taping the electronic components.