Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2001-12-26
2004-11-23
Cuneo, Kamand (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S260000, C428S901000
Reexamination Certificate
active
06822170
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an embedding resin for embedding electronic parts such as chip capacitors, chip inductors, chip resistances, etc., in the inside of a substrate and to a wiring substrate (i.e., wiring board) having embedded electronic parts in the inside of the substrate. Particularly, the invention is suitable for a multilayer wiring substrate having formed fine wiring layers having a width of not wider than 150 &mgr;m on the embedding resin, a package for containing (receiving) a semiconductor element, etc.
2. Description of the Related Art
Recently a multichip module (MCM) mounting many semiconductor elements on a build-up wiring substrate has been investigated. In the case of mounting electronic parts such as chip capacitors, chip inductors, chip resistances, etc., it is general to surface-mounting the electronic parts on a wiring layer for mounting formed on the surface of a wiring substrate using a solder.
However, when electronic parts are surface-mounted on the surface of a build-up wiring substrate, definite mounting area for various electronic parts is required, whereby there is, as a matter of course, a limit for the miniaturization. Also, by treating a wiring in the case of carrying out surface-mounting, the occurrence of a parasitic inductance, which is undesirable for characteristics, is increased and there is a problem that the correspondence of electronic instruments to high frequency becomes difficult.
For solving these various problems, various methods of embedding electronic parts in the inside of a substrate have been investigated. For example, Japanese Patent Laid-Open No. 126978/1999 discloses a method of, after previously solder-mounting electronic parts to a wiring substrate having a transfer sheet made of a metal foil, transferring the electronic parts, but, there remains a problem in the position precision, etc., at mounting. Also, Japanese Patent Laid-Open No. 124352/2000 disclosed a multilayer wiring substrate obtained by build-upping an insulating layer on electronic parts embedded in the inside of a core substrate.
For embedding electronic parts disposed in a wiring substrate in the inside of the substrate, it is necessary to embed the gaps among the core substrate and the electronic parts with the resin and electrically connecting the electrodes of the electronic parts to the wirings formed on the insulating layer by electroless plating, etc. In this case, by an ordinary embedding resin, the adhesion with a plated layer, which becomes the wiring, cannot sufficiently be insured to cause a problem of generating blister of plated layers, etc., in a reliability test. For example, even when the resin has a peeling strength exceeding 588 N/m in an initial state, but since by the influences of heat and moisture of the using environment, the peeling strength is deteriorated to become lower than 588 N/m, which gives a problem. Particularly, when a fine wiring layer having a width of not wider than 150 &mgr;m is formed On an embedding resin or when a wiring layer of passing a large electric current, such as a power source layer is formed, it become a remarkably severe problem.
For improving the adhesion of the embedding resin and the plated layer, a method of first embedding the electronic parts using the embedding resin, then after roughening the surface of the embedding resin with an oxidizing agent such as permanganic acid, chromic acid, etc., a wiring layer is formed by plating, and making build-up layer (forming multilayers) is considered. This is because by the anchoring effect of the unevenness of the roughened surface, the adhesive force with the plated wiring layer is increased. This is known as a method of improving the adhesion of the wiring layer of a build-up wiring substrate and the insulating layer. However, for an embedding resin, the manner of easily roughening is not utterly considered and by the above-described method, the remarkable improvement of the adhesion is hard to be expected.
SUMMARY OF THE INVENTION
An object of the invention is to provide an embedding resin, which increases the mounting density of a wiring substrate mounting thereon electronic parts and obtains a high reliability in a reliability test, such as a heat resistance, a water resistance, etc., and to provide a wiring substrate using the resin.
The embedding resin of the invention is an embedding resin for embedding electronic parts disposed in an opening (a throughhole) or a concave portion such as cavity, etc., formed in a substrate, wherein the peeling strength of a copper layer after a pressure cooker test (121° C., 100% by mass (by weight) humidity, 2.1 atm and 168 hours) of the substrate having formed the copper plate on the cured product of the embedding resin is at least 588 N/m (0.6 kg/cm). The peeling strength after the pressure cooker test (121° C., 100% by mass humidity, 2.1 atm, and 168 hours) is more preferably at least 700 N/m (0.71 kg/cm). Since even by testing under such conditions, the peeling strength still insures the values of at least 588 N/m (0.6 kg/cm), even when a fine wiring layer having a width of not larger than 150 &mgr;m is formed on the embedding resin and even when a wiring layer passing a large electric current, such as a power source layer is formed thereon, a high adhesive reliability can be insured.
In addition, the above-described electronic parts include passive electronic parts such as a chip capacitor, a chip inductor, a chip resistance, a filer, etc.; active electronic parts such as a transistor, a semiconductor element, FET, low-noise amplifier (LNA) etc., and other electronic parts such as a SAW filter, a Lc filter, an antenna switch module, a coupler, a diplexer, etc.
Also, in the embedding resin of the invention, it is preferred that the peeling strength of a copper layer in a pressure cooker test (121° C., 100% by mass humidity, 2.1 atm and 336 hours) of a substrate hating formed the copper layer on the cured product of the embedding resin is at least 600 N/m (0.61 kg/cm). Since even by testing under such a severe condition, the peeling strength still insures the values of at least 600 N/m (0.61 kg/cm), even when a wiring layer for a power source layer connected to electronic parts such as a capacitor having a power source supplying function is formed on the cured product of the embedding resin, a higher adhesive reliability can be insured.
The measurement method of the peeling strength is carried out according to JIS C 5012 (1993), and in this case, the width of the copper layer is 10 mm. The peeling strength of peeling the copper layer from the surface of the embedding resin to the direction of 90 degree (vertical direction) at a pulling speed of 50 mm/minute is measured.
In the embedding resin of the invention, for coloring the resin to a black-base while keeping the peeling strength of the copper layer after the pressure cooker test (121° C., 100% by mass humidity, 2.1 atm and 168 hours) at least 588 N/m (0.6 kg/cm), it is better to add carbon black in an amount of not more than 0.5% by mass, and preferably not more than 0.3% by mass. This is because the embedding resin can be colored to a black-base without reducing the adhesive reliability of the wiring layer at a high temperature and a high humidity and the volume resistance, which is the index of the insulating property.
Also, in the embedding resin of the invention, for coloring the resin to a black-base while keeping the peeling strength of the copper layer after the pressure cooker test (121° C., 100% by mass humidity, 2.1 atm and 336 hours) at least 600 N/m (0.61 kg/cm), it is better to add carbon black in an amount of not more than 0.4% by mass, preferably not more than 0.3% by mass, and particularly preferably not more than 0.2% by mass.
This is because by increasing the adhesion of the wiring layer at a high temperature and a high humidity, the occurrence of the causes of inferiorities such as blister in the production process of the wiring substrate is prevented, whereby the improvement
Kashima Hisahito
Kojima Toshifumi
Ohbayashi Kazushige
Takeuchi Hiroki
Cuneo Kamand
NGK Spark Plug Co. Ltd.
Norris Jeremy
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