JPH0722795A - Fixation jig for thin board - Google Patents

Abstract

PURPOSE:To keep the flatness of a printer-circuit board uniform and with high accuracy and to make the production of a bridge between lend wires for an LSI extremely small in a reflow soldering operation by a method wherein an adhesive silicone rubber layer which is composed of the hardened substance of an addition hardening-type liquid silicone rubber compound is former on a flat board. CONSTITUTION:An SUS-made metal flat board 2 is coated uniformly with an adhesive silicone rubber layer 1 in a film thickness of 500mum. A thin board 3 is flattened and fixed to the SUS-made metal flat board 2 by the adhesive force of the adhesive silicone rubber layer 1. As the flat board to be used, a metal flat board, a plastic flat board, a ceramic flat board or the like is enumerated. In addition, it is desirable that the adhesive force of the adhesive silicone rubber layer formed on the flat board is at 10g/25mm to 1000g/25mm and that the thickness of the silicone rubber layer is uniform at 10 to 1000mum. Since the adhesive silicone rubber layer is formed over the whole face of the thin board, the thin board can be positioned, attached or removed easily when it is fixed, and the title fixation jig can be automated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for fixing a substrate, which is used in a process of mounting electronic parts on a thin substrate.

[0002]

2. Description of the Related Art In recent years, a flexible printed circuit board (hereinafter referred to as an FPC board) in which a polyimide film and a conductor for a circuit are laminated is used in the field of electronics. The mounting process of electronic parts (for example, LSI, capacitors, resistors, inductors, filters) on the FPC board includes cream solder printing process, electronic part mounting process,
It is composed of a reflow soldering step and a cutting step. Through the above steps, the FPC board is flattened and fixed, and conventionally, the printed board is placed on a metal flat plate in order to convey the inside of each step and between the steps. This was done by attaching and fixing with heat resistant tape.

[0003]

However, the work of attaching the heat-resistant tape is difficult to automate with a robot or the like, so that the work has to be done manually. Also, when the FPC board is detached from the metal flat plate, the FPC board must be manually removed in the same manner, which is unsatisfactory in terms of mass productivity and cost. Further, since the warp of the FPC board cannot be completely corrected, there is a problem that a bridge is generated between the lead wires of the LSI during the solder reflow and the circuit is short-circuited. The present invention has been made in order to solve such problems.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that the FPC board may be fixed by a silicone rubber layer having an adhesive property, and have arrived at the present invention. It was That is, the gist of the present invention is a fixing jig for a thin substrate, which is characterized in that an adhesive silicone rubber layer is provided on a flat plate. The present invention will be described in detail below.

The flat plate used in the fixing jig for a thin substrate of the present invention includes a metal flat plate, a plastic flat plate, a ceramic flat plate and the like. As the metal flat plate, for example, a known metal flat plate made of SUS, aluminum, iron, copper or the like can be used, and as the plastic flat plate, for example, polyether sulfone, polyether ketone, polyether imide, polyether sulfide, polyarylate, polyimide. It is possible to use a material having excellent heat resistance such as, and as the ceramic flat plate, for example, alumina, sialon, zirconia,
Aluminum nitride, silicon nitride, silicon carbide, titanium nitride and the like can be used.

The adhesive force of the adhesive silicone rubber layer provided on this flat plate is preferably 10 g / 25 mm to 1000 g / 25 mm, more preferably 40 g / 25 mm to 400 g / 25 mm. Also, the thickness of the adhesive silicone rubber layer is 10-1000μ.
m is preferable, but more preferably 200 to 600
It is in the range of μm. Further, it is preferable that its thickness is uniform. It is desirable that the adhesive silicone rubber layer is provided so as to cover the entire surface of the thin substrate. By doing so, positioning and attachment / detachment at the time of fixing the thin substrate can be facilitated and automation can be performed, and the flatness of the substrate can be maintained.

To form an adhesive silicone rubber layer,
The curable composition as a raw material may be applied to the flat plate surface by a known screen printing method, dip method, doctor blade method, knife coating method, bar coating method, spin coating method, or the like and cured. You may heat as needed when hardening.

The key point of the jig of the present invention is that it is provided with an adhesive silicone rubber layer, and the raw material composition for forming this silicone rubber layer is an adhesive that satisfies the above-mentioned preferable adhesive strength. There are a wide variety of layers that provide layers. However, the preferable raw material composition in view of processability is an addition-curable liquid silicone rubber composition. Among them, A) an alkenyl group-containing organopolysiloxane containing an average of 0.5 or more alkenyl groups in one molecule, and B) an organohydro containing at least two hydrogen atoms bonded to silicon atoms in one molecule. Particularly preferred are those containing genpolysiloxane and C) a platinum group metal-based catalyst and having a molar ratio of the hydrosilyl group contained in component B) to the alkenyl group contained in component A) of 0.1 / 1 to 1.5 / 1. preferable.

Next, the components A), B) and C) will be described. The alkenyl group-containing organopolysiloxane of component A) has an average compositional formula (1) R _n SiO _{(4-n) / 2}
The average number of alkenyl groups contained in one molecule is 0.5 or more. This alkenyl group serves as a cross-linking point during curing.
The composition will not cure if no molecule contains more than one molecule. Therefore, the number of alkenyl groups referred to here is
A) is the average number of alkenyl groups when the component is a mixture of molecules containing 0, 1, 2 or more alkenyl groups in one molecule, and the A) component consists of a single molecular species. In this case, it is necessary that one molecule contains two or more alkenyl groups.

R in the above average composition formula is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a hexyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group and an allyl group, and a phenyl group. , Aryl groups such as tolyl groups, or chloromethyl groups in which some or all of the hydrogen atoms bonded to carbon atoms of these groups are replaced with halogen atoms, cyano groups, trifluoropropyl groups, cyanoethyl groups, etc. The same or different unsubstituted or substituted monovalent hydrocarbon radicals selected, n being 1.98
It is said that it is a positive number of up to 2.01, but preferable examples of R are methyl group, ethyl group, phenyl group, trifluoropropyl group, cyanoethyl group, vinyl group and allyl group,
In particular, when the methyl group is less than 50 mol%, the original properties of methylpolysiloxane are lost and the raw material cost becomes high. Therefore, a methyl group of 50 mol% or more, preferably 80 mol% or more It is good to say A vinyl group is preferable as the alkenyl group. The average degree of polymerization of the component (A) is preferably 1500 or less, and if it is larger than that, the fluidity of the composition deteriorates.

The component (B), an organohydrogenpolysiloxane, is composed of a linear, branched or cyclic molecule containing at least two hydrogen atoms directly bonded to silicon atoms in one molecule. is there. The component B) reacts with the component A) and acts as a crosslinking agent. The amount of component B) added is usually 0.1 to 1.5 equivalents, preferably 0.2 to 1.2 equivalents, per one alkenyl group contained in component A). If it is less than 0.1 equivalent, the crosslink density becomes too small, the strength of the cured composition becomes insufficient, and the heat resistance becomes poor. When it is more than 1.5 equivalents, foaming problem due to dehydrogenation reaction may occur, or the flexibility of the cured product may be lost.

The platinum group metal-based catalyst which is the component C) is for accelerating the addition reaction. Specific examples thereof include platinum black, chloroplatinic acid, an alcohol modified product of chloroplatinic acid, a complex of chloroplatinic acid with an olefin, vinylsiloxane or acetylene alcohol. The amount of component C) added may be selected according to the desired curing rate, but is usually 0.1 to 500 ppm, preferably 1 to 200 ppm in terms of platinum amount relative to component A).

In addition to the components A) to C), known dry silica (fume method) and / or wet silica (wet method) may be added as a reinforcing filler. The silica may be blended as a surface-treated silica having improved dispersibility by treatment with dimethyldichlorosilane or hexamethyldisilazane to adjust the activity. In addition, quartz powder,
Fillers such as ferric oxide, aluminum oxide and calcium silicate may be added.

As other compounding ingredients, vinyl group-containing organopolysiloxanes such as methylvinylcyclotetrasiloxane, triallyl isocyanurate, acetylene alcohol and siloxane thereof are used for the purpose of controlling the curing speed and storage stability of the composition. Modified products and the like can be used.

Further, a compound represented by the following formula for improving the adhesiveness to a flat plate

[Chemical 1] And / or a known silane coupling agent may be added.

Further, the surface of the flat plate is coated in advance with a treatment agent selected from the above-mentioned silane coupling agent, titanium-based coupling agent and a mixture thereof, and the adhesive silicone rubber layer is firmly bonded through this coating layer. It can also be attached to.

[0017]

EXAMPLES Examples of the present invention will be given below. Example 1 Vinyl group-containing organopolysiloxane 100 consisting of 95 mol% of dimethylsiloxane units and 5 mol% of methylvinylsiloxane units and having a viscosity at 25 ° C. of 8500 cp.
Parts by weight, formula

[Chemical 2] 5.7 parts by weight of methylhydrogenpolysiloxane, 0.28 parts by weight of a solution of chloroplatinic acid in 2-ethylhexanol (platinum content 2%), formula

[Chemical 3] 1.0 parts by weight of methyl vinyl polysiloxane, 21.4 parts by weight of Crystallite VX-X (Tatsumori Co., trade name), Mi
An addition-curable liquid silicone rubber composition was prepared by uniformly mixing 21.4 parts by weight of nU-Sil (manufactured by Pennsylvania, trade name) and 20 parts by weight of Elosil 300 (manufactured by Nippon Aerosil Co., Ltd.).

Next, a SUS metal flat plate (L: 200 × W: 180 ×
H: 1.5 mm) was coated with a 5 wt% toluene solution of γ-glycidoxypropyltrimethoxysilane as a primer and air dried at room temperature for 30 minutes, and then the above silicone rubber composition was formed into a film by a bar coating method. It was evenly applied to a thickness of 250 μm. Then, in a hot air dryer at 150 ° C,
After heating for 30 minutes, the silicone rubber was cured to prepare a fixing jig for a thin substrate.

Table 1 shows characteristics such as the adhesive force of the adhesive silicone rubber layer of the fixing jig for the thin substrate.

[Table 1]

Using the obtained jig for thin substrate,
A polyimide FPC board with a copper circuit pattern is fixed on the adhesive silicone rubber layer, flattened, screen-printed with cream solder, and then electronic components are mounted, using a hot air drying oven at 150 ° C. 60 seconds, then 200
Solder reflow was performed under the condition of 60 ° C. for 60 seconds. Then, it was left to cool to room temperature, and the FPC board was peeled off from the fixing jig to obtain a completed FPC board on which electronic components were mounted. At this time, it was not observed that the adhesive silicone rubber layer of the fixing jig for a thin substrate was deteriorated. Further, it was confirmed that the adhesive force of the adhesive silicone rubber layer after repeating the above steps 50 times was not particularly changed, and the practicality was high.

(Example 2) 45 parts by weight of dimethylpolysiloxane having a viscosity of 800 cp at 25 ° C. and having both ends blocked, dimethylpolysiloxane having a viscosity of 800 cp at 25 ° C. and dimethyl having each end blocked with dimethylsiloxy and dimethylvinylsiloxy. 55 parts by weight of vinylsiloxy one end-capped dimethylpolysiloxane, 1.0 part by weight of dimethylhydrogensiloxy both-endcapped methylhydrogenpolysiloxane containing 0.54 mol% of hydrogen atoms bonded to silicon atoms having a viscosity of 8 cp at 25 ° C. , 0.05 part by weight of vinyl siloxane complex of chloroplatinic acid (platinum content 1% by weight), 0.001 part by weight of ethynylcyclohexanol, 15 parts by weight of fumed silica surface-treated with hexamethyldisilazane, and formula as an adhesion improving component.

[Chemical 4] An addition-curable liquid silicone rubber composition was prepared by uniformly mixing 1.0 part by weight of the compound represented by

In the same manner as in Example 1, the above silicone rubber composition was uniformly coated on a SUS metal flat plate so as to have a film thickness of 300 μm, and then heated at 180 ° C. for 5 minutes in a hot air dryer to cure the silicone. The rubber was cured to prepare a fixing jig for a thin substrate. Table 2 shows characteristics such as the adhesive force of the adhesive silicone rubber layer of this fixing jig for a thin substrate.

[Table 2]

Using the obtained thin substrate fixing jig,
Electronic components are mounted on the FPC board in the same manner as in Example 1,
The finished product of the FPC board on which the electronic components were mounted was prepared. The adhesive silicone rubber layer of this fixing jig for a thin substrate did not show any deterioration in physical properties even after repeated use 50 times as in the case of Example 1.

(Comparative Example 1) A polyimide FPC board having a copper circuit pattern formed thereon was fixed on the SUS metal flat plate used in Example 1 with a heat resistant tape, and the same procedure as in Example 1 was performed. After mounting the electronic parts in the process,
There was a problem that a solder bridge was generated between the LSI lead wires. Table 3 shows the defect rates due to the solder bridges of the examples and comparative examples.

[Table 3]

(Embodiment 3) Next, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. In FIG. 1, an adhesive silicone rubber layer 1
Is uniformly coated on the SUS metal flat plate 2 with a film thickness of 500 μm. The thin substrate 3 is flattened and fixed to the SUS metal flat plate 2 by the adhesive force of the adhesive silicone rubber layer 1.

[0026]

EFFECT OF THE INVENTION With the fixing jig for a thin substrate of the present invention, F
In the electronic component mounting line on the PC board, the flatness of the printed circuit board can be maintained uniformly and with high accuracy, which facilitates the mounting of electronic components and causes a bridge between the LSI lead wires during solder reflow. Has become extremely less. Further, a thin substrate can be easily positioned and attached to and removed from the jig of the present invention, and automatic attachment and detachment using a robot or the like are possible, which is excellent in mass productivity and is advantageous in cost. Furthermore, since the adhesive silicone rubber has excellent heat resistance, it can be repeatedly used in a heating furnace for reflow solder exposed to hot hot air, which is advantageous in terms of running cost. As described above, the jig of the present invention has many excellent points, and the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Adhesive Silicone Rubber Layer 2 SUS Metal Flat Plate 3 Thin Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takehide Okami Inami, Matsuida-cho, Usui-gun, Gunma 1-10 Hitomi, Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Masaaki Matsumura Matsuida-cho, Usui-gun, Gunma Hitomi No. 1 10 Shin-Etsu Chemical Co., Ltd., Silicone Electronic Materials Research Laboratory (72) Inventor Ryuichi Handa Matsuida-cho, Usui-gun, Gunma No. 1 Hitomi 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Mitsumasa Magutani 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation

Claims (3)

[Claims] 1. A fixing jig for a thin substrate, comprising an adhesive silicone rubber layer provided on a flat plate. 2. The fixing jig for a thin substrate according to claim 1, wherein the adhesive silicone rubber layer comprises a cured product of an addition-curable liquid silicone rubber composition. 3. An addition-curable liquid silicone rubber composition comprising: A) an alkenyl group-containing organopolysiloxane having an average of 0.5 or more alkenyl groups in one molecule, and B) a silicon atom in one molecule. Containing an organohydrogenpolysiloxane containing at least two hydrogen atoms, and C) a platinum group metal-based catalyst, the molar ratio of the hydrosilyl group contained in component B) to the alkenyl group contained in component A). 0.1 / 1 ~ 1.5 / 1
The fixing jig for a thin substrate according to claim 2.