JPS61254636A - Tray for holding electronic part - Google Patents

Abstract

PURPOSE:To obtain a tray for holding electronic parts, resistant to high- temperature treatment, and having excellent antistatic effect, by applying a one-pack type polyurethane lacquer containing conductive carbon to the surface of a molded article of polyethylene terephthalate having a specific crystllinity. CONSTITUTION:A polyethylene terephthalate resin molded article having a crystallinity of 20-50%, preferably 25-40% is produced by the vacuum forming or pressure forming of a polyethylene terephthalate resin having a crystallinity of 5-10% and preferably containing organic or inorganic crystal nuclei. At least one surface of the molded article is coated with a one-pack type polyure thane lacquer containing preferably 8-12% conductive carbon at a thickness of preferably 4-20mu, and preferably coating the coated surface further with a one-pack type polyurethane lacquer containing 0-4% conductive carbon at a thickness of 0.5-10mu to obtain the objective tray for holding electronic parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an electronic component storage tray, and particularly to an electronic component storage tray C2 that is resistant to high temperature treatment and has an excellent antistatic effect.

(Prior Art) Storage trays for transporting electronic components are generally made of thermoplastic plastic and have their surfaces treated with antistatic or conductive treatment for ease of moldability and handling.

This antistatic treatment usually has a surface resistance value of 10 to 1.
0 Ω nonionic, anionic, cationic, or amphoteric antistatic agent applied to the surface or kneaded with resin.
However, this surface coating has problems with surface smoothness, adhesion to the base material, abrasion resistance, and durability, and kneading resin has the disadvantage of being thermally decomposed during processing. be.

Therefore, there is a known method of kneading conductive carbon into this material, but this method is not economical as it requires a high filling rate to compensate for the destruction of the carbon struc- ture during processing. C: There is a disadvantage that the physical properties deteriorate significantly when molded products of the same thickness are made, and the method of applying conductive paint containing conductive carbon has the disadvantage that it decomposes during heating depending on the type of binder. There are drawbacks such as generation of gas, softening of the film, and peeling from the base material.

In addition, this type of electronic component storage tray is usually used at room temperature, but it can also be used, for example, when removing residual monomers, solvents, moisture, etc. contained in the IO sealant. May be subjected to high temperature treatment at 50°C.
Even more flat! Regarding the O package, it is necessary to preheat it when surface mounting it on a board by soldering, so it is required to maintain its shape continuously even at temperatures like 11. Currently, there are only metal ones that can withstand such high temperatures, and there is a desire for a plastic one that can also be used for this purpose.

(Structure of the Invention) The present invention relates to a plastic part storage tray that solves the above-mentioned disadvantages. One-component polyurethane lacquer containing conductive carbon! It is characterized by being coated.

In other words, as a result of various studies on electronic component storage trays that can withstand high-temperature treatment and have excellent antistatic effects, the inventors of the tree discovered that the main island uses polyethylene terephthalate resin as its plastic material and has a crystallinity level of 2.
0 to 50% molded product, the surface of which is coated with liquid type polyurethane lacquer containing conductive carbon;
This product retains its shape even after baking at 120 to 150°C, and its dimensional change rate is C'- within 1%.This polyurethane lacquer coating exhibits an excellent antistatic effect; Since the melting point is over 200℃, we discovered that the antistatic effect does not change even after baking treatment. The present invention was completed after extensive research.

The polyethylene terephthalate resin used to form the electronic component storage tray of the present invention must be polyethylene terephthalate or ethylene terephthalate copolymer in which 80% or more of the repeating units are ethylene terephthalate units. may contain additives such as organic or inorganic crystal nuclei and antiblocking agents. This polyethylene terephthalate molded product has a melting point of 256°C and is highly heat resistant, but it softens when heated, especially molded products with a crystallinity of 20% or less when baked. It has a tendency to curl, and if this reaches 50%, the MS resistance will be extremely poor, causing a practical problem.
0% III! t1, and the preferable range is 25 to 40%, but in order to adjust the crystallinity, f2 is non-grade polyethylene terephthalate or preheated to 80 to 150°C. When forming polyethylene terephthalate with a degree of crystallinity of 5 to 10% by vacuum forming or air pressure press forming, the polyethylene terephthalate ν is heated at the same time as the forming C: to obtain the desired degree of crystallinity. If the crystallinity is increased to 10% or more before the molding process, heat molding can be At times, crystallization progresses rapidly, resulting in inferior suction and air pressure effects, and the shape of the outer and inner corners of the storage tray as a molded product becomes disordered. Therefore, the degree of crystallinity before molding is 10%. It is better to do the following.

The electronic component storage tray of the present invention has a crystallinity of 20 to 50%.
A liquid-type polyurethane coating containing conductive carbon black is applied to the surface of a polyethylene terephthalate resin molded product, and the surface is conductive treated to give it an antistatic effect. This polyurethane lacquer is made by reacting the OH groups of a difunctional polyol, a glycol, with the NOO groups of a diisocyanate in a solution of 1 in NOO10R to give it long-term durability against baking treatments. Plastic linear polyurethane dimethylformamide, methyl ether ketone, toluene, acetic acid t/L/
It may be a liquid type product dissolved in a solvent such as, for example, which cures at the same time as the solvent evaporates and evaporates, and since no active isocyanate remains, it does not decompose or generate corrosive gases.

In addition, this polyurethane lacquer needs to be made conductive by adding conductive carbon black to make the coating film conductive and exhibit an antistatic effect. ν Enblack EC (product name manufactured by Lion Agzo), Furnace Black, Acetylene Black, Palcan X0-72
(product name manufactured by the same company) may be used alone or as a mixture, but this additive level is 5 to 50% for polyurethane lacquer.
It may be set to 20%, preferably 8 to 12%.

This polywanthanum lacquer containing carbon black can be applied to molded products using a roll coater, gravure coater, knife coater, flow coater, or the Silksgeleen method, but the thickness of this coating film must be less than 1 μm. Because the gaps between carbon particles are large, the conductivity of the coating film becomes insufficient, and if the gap is 50μ or more, there will be problems such as flow of the coating liquid, air entrainment, and residual solvent, so it is recommended that the gap be in the range of 1 to 50μ. This is preferably 4 to 20μ. Since this coating film contains carbon black, the surface resistance value is 10 to 10 even for a thin film of 1 to 3 houses.
Ω, and this coating film has a melting point of over 200°C, so the molded product has an antistatic effect, and the baked coating film has a high content of conductive carbon black, so the surface Since it has low friction and is easily damaged, it is preferable to further overcoat the coated surface with a poly-9 urethane lacquer containing 4% or less of conductive carbon black. This overcoat is 0.5-1% when the carbon black content is 0-1%.
μ, when it is 2 to 4%, if it is applied to a thickness of 2 to 10 μ, this coating film is extremely thin, so @1 layer conductor 1
! The tunneling effect 22 caused by r- protects the surface of the molded article without impairing its conductivity.

As described above, the electronic component storage tray of the present invention can be manufactured by applying a polyurethane lacquer containing carbon black to the surface of a polyethylene terephthalate resin molded product having a crystallinity of 20 to 50%. , Boliet Ren.

Polyurethane coating on the surface of terephthalate resin molded product 1
ri 礪 -me, -Mk 太”?su shi scolding tλshi
z1 Ma Roku! Since the adhesion with the car paint film is poor and this paint film may peel off, in manufacturing this, a sheet is made from polyethylene terephthalate resin, and after applying this sheet C-polyurethane lacquer, This is preferably formed into a desired shape by vacuum forming or pressure press forming.

As mentioned above, the electronic component storage tray obtained is a molded product made of polyethylene terephthalate resin with good heat resistance, and a polyurethane lacquer coating with a melting temperature of 200°C or higher is provided on the surface. Baking temperature (
: In addition to being durable for long periods of time, this product also has good dimensional stability under high temperatures, and since the polyurethane lacquer coating is electrically conductive, it has excellent antistatic effects, and is also surface resistant. It has the advantages of good abrasion resistance, light weight, and easy transportation.

Next, two examples of the present invention will be given.

Example A polyethylene terephthalate resin having an intrinsic viscosity of 0.7 and a glass transition point of 81° C. was melt-extruded from a T-die using an extruder and rapidly cooled to produce an amorphous sheet with a thickness of 0.5 tml.

Next, coat one side of this sheet with a gravure coater (depth 4).
A one-component polyurethane lacquer consisting of 10% resin, 10% conductive carbon black, 50% ketone solvent, 20% aromatic solvent, and 10% ester solvent was made to a thickness of 12μ using 4-45μ). After coating and drying, 10% resin content, 2% conductive carbon black content,
A one-component polyurethane lacquer made of 10% ketone solvent, 48% aromatic solvent, 20% medium-boiling alcohol, and 10% high-boiling alcohol was applied in the same manner to a thickness of 1.2μ (two coats, dried, and Using a vacuum forming machine, the mold temperature is 160℃.
When an electronic component storage tray was made by molding at a sheet temperature of 160°C, the surface resistance value of this product was 5 x 10
' It was Ω.

GG C = This tray I: Flat IO Pa Socage 50
When I put a tray on it and left it in an oven at 125℃ for 24 hours and took it out, there was no change in this IO, and the surface resistance value of this tray was 5 x 100, which was no change at all. The dimensional change rate was a shrinkage rate of 0.31%.

Comparative Example A vinyl chloride/acrylic paint containing 10% resin, 5% carbon black, 60% ketone solvent, and 25% aromatic solvent was applied to the polyethylene terephthalate resin sheet prepared in Example in the same manner as in Example. Thickness: 12 μC: After coating and drying, vacuum forming was performed in the same manner as in the example to form an electronic component storage tray.
It showed a surface resistance of 0.

Next, we placed 50 flat IC packages on this tray and left them in an oven at 125°C for C24R. When we took them out, we found that all of the ICs were attached to the conductive paint that had softened on the lead frame, and they could be used as IOs. I couldn't.

Claims (1)

[Claims] 1. A one-component polyurethane lacquer containing conductive carbon is coated on at least one side of a polyethylene terephthalate resin molded product having a crystallinity of 20 to 50%. Electronic parts storage tray. 2. The electronic component storage tray according to claim 1, wherein the polyethylene terephthalate resin contains organic or inorganic crystal nuclei and has a crystallinity of 10% or less. 3. The electronic component storage tray according to claim 1, wherein the polyethylene terephthalate resin has a crystallinity of 20 to 50% by vacuum forming or pressure forming. 4. Apply a one-component polyurethane lacquer containing 5 to 20% conductive carbon to a thickness of 1 to 50 μm on at least one side of the polyethylene terephthalate resin molded product, and then coat this with 0 to 4% conductive carbon. The electronic component storage tray according to claim 1, which is coated with a one-component polyurethane lacquer to a thickness of 0.1 to 10 μm.