JPH11274245A - Material for mounting semiconductor, method for using the same and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor mounting material, with which any crack caused by a thermal expansion coefficient difference after mounting does not occur on a solder ball, method for using the same and semiconductor package provided by using this material. SOLUTION: Concerning the semiconductor mounting material which uses a resin film or the like as a substrate and has two-dimensionally arranged electrodes for a connection with a mother board or the like while using a reinforcing plate forming an adhesive agent layer at the part required for assembly, the said reinforcing plate can be detached after mounting, any material such as glass capable of transmitting infrared rays is used as the reinforcing plate, and an ultraviolet curing adhesive agent is used as an adhesive agent. When mounting a semiconductor device in a substrate for mounting such as a printed circuit board while using a solder ball or the like, this package is irradiated with ultraviolet rays after mounting, adhesive power is eliminated by hardening the adhesive agent and the reinforcing plate is detached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing plate for an electronic device such as a semiconductor device, and more particularly to a semiconductor package using a resin film or the like as a substrate on which a semiconductor chip or other electronic components are mounted.

[0002]

2. Description of the Related Art In an electronic device such as a semiconductor device, a flexible substrate or a TAB mounting type thin package is used in order to reduce the size and thickness of the electronic device itself or various kinds of electronic devices in which the electronic device is assembled. I have. As the base material, a substrate material in which a conductor layer is provided on a resin film made of a tape or other appropriately shaped polyimide or the like is used. By the way, since the resin film that constitutes these substrate materials is generally soft, when a semiconductor chip or other electronic components are mounted on a substrate obtained using the substrate material, they are supported. Not strong enough to do so.

Further, with the recent increase in the number of pins and the density of the semiconductor package, a method of mounting the semiconductor package on a circuit board is represented by a ball grid array (BGA) rather than a conventional peripheral lead type represented by a QFP. Are shifting to grid terminal arrangement type mounting. The resin film substrate material has been widely used as a base material for the BGA. In the BGA, the flatness of the package itself needs to be better than that of a conventional QFP or the like in order to make contact with the motherboard using solder balls arranged in a grid.

For example, in the case of an area array type semiconductor package represented by BGA, as described above,
At the time of mounting, it is necessary to make contact with a printed board serving as a mounting board by solder balls. At this time, the yield at the time of mounting depends on the level of flatness of the package.
That is, when the flatness is poor, a phenomenon in which some solder balls are lifted from the electrode pads formed on the printed circuit board is observed, resulting in an open defect.

[0005] In order to ensure such strength and flatness, a metal reinforcing plate for support is bonded and used on a resin film. For the metal reinforcing plate for support, a material having a coefficient of thermal expansion close to that of another member used for the package has been studied and used.

[0006]

However, since a resin film such as polyimide is used as a substrate material, even if the coefficient of thermal expansion of the supporting metal reinforcing plate is made to match the resin film, or even if the motherboard is mounted on the metal reinforcing plate. Even when a printed circuit board using a glass epoxy plate is used, cracks due to a difference in thermal expansion coefficient enter a solder ball in a durability test after mounting.

[0007] In order to solve this problem, a structure has been studied in which the adhesive layer of the supporting metal reinforcing plate has elasticity to relieve the stress due to the difference in thermal expansion, but it is still not enough. It is.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and a semiconductor mounting material which does not cause cracks in solder balls due to a difference in thermal expansion coefficient after mounting, a method of using the same, and a method of using the same. The task is to provide the obtained semiconductor package.

[0009]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems uses a resin plate or the like as a base material, and uses a reinforcing plate having an adhesive layer formed at a portion required for assembly, and a motherboard or the like. In a semiconductor mounting material having two-dimensionally arranged electrodes for connection with the semiconductor device, the reinforcing plate is removable after mounting, using a material that transmits ultraviolet light such as glass as the reinforcing plate, and an ultraviolet curing type as an adhesive. Is used. Then, when mounting the semiconductor device on a mounting board such as a printed board with a solder ball or the like, after the mounting, the package is irradiated with ultraviolet rays, the adhesive is cured to eliminate the adhesive force, and the reinforcing plate is removed. This is how to use the semiconductor mounting material. Further, the present invention is a semiconductor device in which a semiconductor element is mounted on this semiconductor mounting material.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the case where a flexible resin substrate is used as a package substrate, it is necessary to attach a certain reinforcing plate to the package to secure the flatness of the package. However, by firmly attaching the reinforcing plate to the package, the stress caused by the difference in thermal expansion coefficient cannot be released, and the solder ball portion is broken (defect such as crack) due to stress concentration after mounting. Without the reinforcing plate, the stress caused by the difference in thermal expansion after mounting can be released due to the flexibility of the substrate used for the package.

Therefore, in order to obtain a highly reliable package after mounting with a good yield, it is only necessary that there is a reinforcing plate for securing flatness during mounting and that the reinforcing plate can be removed after mounting. The present invention has been made from this viewpoint.

In the present invention, as a method for removing the adhesive, an ultraviolet curing type is used as the adhesive, the adhesive layer is cured by irradiating ultraviolet rays after mounting, and the reinforcing plate can be removed by eliminating the adhesive force. It is. Therefore, the reinforcing plate needs to transmit ultraviolet rays and have a certain rigidity or more. For example, glass can be used.

As a further advantage of the present invention, the removed glass reinforcing plate can be used again for the package, and an improvement in economy can be expected.

[0014]

Next, the present invention will be further described with reference to examples.

(Example 1) First, a PET having a thickness of 38 μm was used.
A film having a 20 μm-thick UV-curable adhesive having room-temperature adhesiveness on one side was prepared. This adhesive was adhered to a glass plate having a thickness of 1 mm so that the surface of the ultraviolet-curable adhesive became the surface, thereby producing a stiffener (supporting reinforcing plate).

Next, a land having a diameter of 0.5 mm and
A stiffener was attached to a TAB tape provided at intervals of m pitches. Next, solder balls were mounted on the lands on the back surface via a flux.

Next, a flux was applied to the surface of the solder ball and mounted on the electrode portion of the printed wiring board. This was placed in a furnace and reflowed for soldering.

Next, ultraviolet rays were irradiated from the glass surface to cure the ultraviolet curable adhesive, and then the glass plate was peeled off.

With this method, 1000 samples were prepared and subjected to a repeated test at a temperature of -65 to 150 ° C. 1000
No repetitions were made, but no abnormality occurred.

Comparative Example 1 mm thick instead of a glass plate
A sample was prepared in the same manner as in the example except that the stainless steel plate was not removed after the solder bonding using the stainless steel plate. Then, a repeated test was performed in the same manner as in the example. As a result, cracks were found in the solder ball portions of the ten samples.

[0021]

According to the present invention, a semiconductor package which can be mounted with good flatness by using a removable glass plate or the like as a reinforcing plate, and has a high reliability because the glass plate or the like is removed after mounting. It can be provided in good yield.

Claims (3)

[Claims] 1. A method using a resin film or the like as a base material,
Using a reinforcing plate having an adhesive layer formed at a part required for assembly, in a semiconductor mounting material having two-dimensionally arranged electrodes for connection to a motherboard or the like, the reinforcing plate is removable after mounting. A material for mounting semiconductors, wherein a material that transmits ultraviolet light such as glass is used as a reinforcing plate, and an ultraviolet-curable adhesive is used as an adhesive. 2. When a semiconductor package is obtained by mounting a semiconductor device on a mounting board such as a printed board with solder balls or the like, a semiconductor package is prepared using the semiconductor mounting material according to claim 1, and then ultraviolet light is applied. Irradiate the package, cure the adhesive and lose the adhesive strength,
A method for using a semiconductor mounting material, wherein a reinforcing plate is removed. 3. A semiconductor device using the semiconductor packaging material according to claim 1.