JPS5813633A - Extraction of water-soluble impurity from resin for encapsulating semiconductor - Google Patents

Abstract

PURPOSE:To separate the water-soluble impurities from the powder of uncured resin for the encapsulation of semiconductors, by curing the powder under the same conditions as the molding of the product, pulverizing the cured product, and extracting the powder by heating in a closed vessel having inner walls coated with a fluorine-contained resin. CONSTITUTION:Only the uncured resin powder is put into a mold same as the mold for the molding of a product, and molded and cured preferably at 180 deg.C and 80kg/cm<2> for 10min. After the after-cure at 180 deg.C for 3hr, the cured product is pulverized, and put into a stainless steel vessel having a thickness of about 5mm. and coated its inner walls with a fluorine-contained resin (e.g. tetrafluoroethylene polymer) with a thickness of about 3mm.. Water is poured into the vessel, and stirred. The water-soluble impurities are separated by the extraction in the extractor at 140-220 deg.C for about 2hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting water-soluble impurities from a resin for semiconductor encapsulation.

Resins for encapsulating semiconductor elements such as epoxy resins and silicone resins affect semiconductor element characteristics depending on the impurities they contain. The surface condition of a semiconductor device directly affects the electrical properties of the device and is sensitive to contamination by 411PK surface impurities. For example, in a resin-sealed product, the element is in direct contact with the resin, and the resin has the property of permeating and absorbing moisture. This rounded moisture and impurity ions dissolved in the water 1, especially halogen ions, are used in semiconductor device electrodes and wiring 4. .

Due to the chemical reaction with the aluminum used, -' insulation properties are reduced. Moreover, these corrode the electrodes in the wiring, causing wire breakage. Therefore, it is desirable that the resin self-sealing contain a small amount of water-soluble impurities.

For example, in the evaluation of sealing resin by the method of extracting impurities in sealing resin, which has been adopted in response to such requests, ti>cured resin that is obtained by curing uncured resin powder at 60°C and then pulverizing it. A method of extracting powder with hot water of 70 to 120°C and measuring the hydrogen ion concentration and electrical conductivity of the extracted water. (2) Mixing uncured resin powder and Aerosil S10: powdered ice to form nine powders. First, heat-treat at 140-200℃ for 10 minutes to harden it, crush it, store the cured resin powder and water in a sealed container aK, extract at 140-200℃ for 2 hours, and remove the extracted water and vapor. Methods for measuring water-soluble impurities such as conductivity, sodium chloride, potassium, calcium, antimony, and magnesium are known. However, with method (l), 1
It takes a long time from 0 to 50 hours, and because of the long time required, impurity contamination is avoided during extraction, reducing analytical accuracy, and impurity extraction t4! The halogen extractor is unsuitable as an evaluation method for rounded resins that produce low levels. In this respect, method (2) is more advantageous than method (1). Generally, when molding a product, a lead frame that has been mounted and bonded in advance is placed in a mold for molding.
Pour the uncured resin powder into the mold and set the molding temperature to 140-1
90'0. Molding pressure 20~too#/cd Molding time 1~
Mold for 5 minutes, harden and k1 after cure at 140-19
The process is carried out at 0"O for 3 to 10 hours. Impurities incorporated in the resin or filler are converted to water-soluble impurities during molding conditions and actor curing, or are contained in the added flame retardant. Bromine and antimony oxide are converted into water-soluble bromine and water-soluble antimony.The amount of water-soluble impurities*t generated during these steps affects the characteristics of semiconductor devices. When evaluating resins, it is important that these water-soluble impurities are completely collected.In the (2) method, these water-soluble impurities are collected at the heating temperature during extraction, and at
, 5 to 20 #/- and is intended to be obtained by extraction. However, since the heating time and pressure are clearly insufficient compared to the product forming conditions, it is natural that the amount of water-soluble impurities produced during actual molding is lower than the amount of water-soluble impurities produced during the actual molding process. In addition, contamination from the Aerosil SiO2 powder added during curing and the material of the sealed container is unavoidable, and because stirring operations are not performed, the hardened powder and water are not mixed together and are completely formed, resulting in dead water-soluble impurities. Not only will not be extracted, but the analysis accuracy will decrease.

The purpose of the present invention is to improve the impurity extraction method in order to ensure resin evaluation using such an extraction method. That is, after curing the uncured resin powder under the same conditions as the actual molding conditions of the product, after-cooling is performed in the same manner to generate the amount of 11111 water-soluble impurities that are generated when the product is finished, and then stirred. The amount of water-soluble impurities produced can be reliably extracted. In order to prevent contamination from the extractor, a closed container whose inner wall was entirely made of fluororesin was used.The container was heated to 140-200°C to accelerate extraction.

Examples will be described below. Pour only the uncured resin powder into a mold similar to the product, molding temperature f180℃, molding weight 80kg/, -n1 when molding? After curing, 10 g of the nine-hardened powder was molded for 10 minutes, hardened, and then crushed at 180'O for 3 hours. 5mm thick stainless steel 8a (straight & 600% depth 39i
n). Next, 50 mj of water and one rotor were added to this, and a stainless steel lid with a wall thickness of 5@tm whose inner surface was coated with a polytetrafluoroethylene polymer with a thickness of 5111 mm was fitted with screws to secure the cap, and then stirred. to thoroughly mix the hardened powder and water in the container. Next, this extractor was left in a drying room whose temperature was controlled to 180'O for 2 hours. The amount of each water-soluble impurity component (ppm) and electrical conductivity (μ7/d) were measured from the extracted water obtained by such an extraction method. The bet results are shown in the table below. For comparison, the same sample was mixed with 10 g of uncured powder and 2 g of Aerosil 5102 powder with an average particle size of 1 mμ under the same curing conditions as the conventional method, and the powder was heat-released at 180°C for 10 minutes. After drying and curing, extraction was performed under the same conditions as in the present invention, and the results of measuring the amount of water-soluble impurity components (ppm) and electrical conductivity f (μ/1) are also shown in the table.

As shown in the margin table below, in this method, compared to the conventional method, the non-defective resin has a lower amount of each water-soluble impurity, especially chlorine, and there is clearly a significant difference in electrical conductivity. However, the amounts of each water-soluble impurity and electrical conductivity of the conventional method were low for both good and defective resins, and the water-soluble impurities vlJ violet and electrical conductivity of the good resin of this method and the defective resin of the conventional method were low. No significant difference was observed. This is because in the conventional method no pressure is applied during curing, rounding is not performed after-squeeze, and impurities in the resin are difficult to convert into water-bathable impurities.

According to the method for extracting impurities in resin for semiconductor encapsulation of the present invention, water-soluble impurities generated during product molding and after-keying can be reliably extracted, making it possible to reliably extract water-soluble impurities that are generated during product molding and after-keying, and can be applied to various molding conditions and differences in actuator characteristics. It is also more reliable than evaluation of sealing resins using other extraction methods. Also, the evaluation of the resin is the same as that obtained from a test using methods other than extraction.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a sealed extractor used in the present invention. +13...-! i t2)...container (3)
...Food nest #fat (4)...Screw diagram 1

Claims (1)

[Claims] The uncured resin powder for semiconductor encapsulation is cured under the same conditions as the product molding conditions, and then the pulverized hardened powder is stored together with water in a sealed extractor whose inner wall is made of fluororesin, and then stirred. 1. A method for extracting water-soluble impurities V in a resin for semiconductor encapsulation, which comprises heating to 140 to 22 G'O after death to extract water-soluble impurities.