Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-11-28
2004-03-02
Chang, Richard (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S846000, C427S097100, C427S099300, C174S264000, C174S266000
Reexamination Certificate
active
06698093
ABSTRACT:
TECHNICAL FIELD
The present invention relates to circuitry forming substrates used in a variety of electronic equipment and a manufacturing method of such circuitry forming substrates.
BACKGROUND ART
In recent years, as electronic equipment is seeing the ever-increasing level of size reduction and circuit density, a shift from conventional one surfaced substrates to two-surfaced substrates and multilayer substrates has been taking place in the area of circuitry forming substrates for mounting electronic components thereon, resulting in stepped up development of a high density circuitry forming substrate that enables the mounting of as many circuits as possible thereon.
With a high density circuitry forming substrate, in place of the conventional method of drilling to bore a hole (through hole) on a substrate, it is being considered to use energy beams such as a laser beam and the like, whereby machining at a higher speed and with a higher degree of definition is made possible. (cf. An article titled “Remarkable Recent Trend in Development of Build-up Multilayer PWB” authored by K. Takagi and appeared in “Surface Mounting Technology” published in January, 1997 from Nikkan Kogyo Shinbun of Japan)
However, with a high density substrate, as the line width and land size of circuits are reduced, the adhesion strength between the substrate and the circuits or the lands is naturally reduced. On the other hand, a high density substrate is usually used in such electronic devices as note PC's, portable telephones, PDA's and the like, and is liable to suffering from such mechanical stresses as caused by dropping, bending, impacting and the like occurring on the part of the electronic devices. As a result, the aforementioned reduction in adhesion strength of the high density substrate has been making a serious problem.
As the substrate material for a high density substrate, most of the time, a resin material is used and a high grade thermosetting resin is usually used from the view points of enhancement in the mechanical strength or heat resistance of the substrate. Although the properties of the substrate itself may be improved, however, the adhesion strength between the substrate and the circuits or the lands is not necessarily intensified when such mechanical stresses as an impact and the like imposed on the substrate are taken into consideration.
Conversely, when a material design and a material selection are carried out for the whole purpose of increasing the adhesion strength, the substrate properties except for the adhesion strength are often degraded. Therefore, it is actually difficult for the substrate material development to be performed so as to satisfy all the requirements involved with a high density substrate.
In addition, with a high density circuitry forming substrate, such connecting means as a conductive paste, a metal plating and the like are used in electrically connecting between layers of the substrate and, on the other hand, a spacing between through holes or non-through holes, which are generally referred to as via holes and formed on the substrate for interlayer connections, and a spacing between the via hole and the adjoining wiring are made smaller and smaller, resulting sometimes in such a serious problem of reliability for the circuitry forming substrate as caused by diffusion of a conductive paste and a plating solution for metal plating to the vicinity of via holes.
DISCLOSURE OF THE INVENTION
A manufacturing method of circuitry forming substrates of the present invention comprises the steps of:
forming through holes or non-through holes on a plate-like or sheet-like substrate formed of a single material or a plurality of materials by irradiating an energy beam on the substrate;
forming a connecting means in the through hole or non-through hole formed in the foregoing hole forming step to connect electrically between the upper surface and the lower surface of the substrate or between the outer layer and the inner layer of the substrate; and
forming a circuit on the surface of the substrate by disposing a conductive layer formed of a metal foil or a thin film on the surface and patterning the cconductive layer to a desired configuration,
in which the foregoing each respective step is performed independently or the elements of each respective step are intermingled with one another for the purpose of achieving what is intended for by the foregoing respective steps, and further comprises the steps of;
attaching by adhesion a film-like separation film on a surface or both surfaces of the substrate before the foregoing step of forming holes, and having part of the separation film transferred onto the substrate.
According to the present invention, a thin foreign material is disposed on the upper surface of a substrate by a transferring method, thereby allowing the adhesion strength of the substrate to be intensified owing to the effect of the foreign material and also enabling the use of an optimum material as the substrate material that makes it possible for the substrate to achieve desired overall characteristics. More specifically, a material, which is different from the substrate material and yet intensifies the adhesion strength of the substrate, is selectively transferred onto the surface of the substrate only in an area where a circuit or a land is disposed, thus allowing a high density and high reliability circuitry forming substrate to be realized without degrading the overall characteristics of the substrate.
In addition, the manufacturing method of circuitry forming substrates comprises the steps of:
forming through holes or non-through holes on a plate-like or sheet-like substrate formed of a single material or a plurality of materials by irradiating an energy beam on the substrate;
forming a connecting means in the through hole or non-through hole formed in the foregoing hole forming step to connect electrically between the upper surface and the lower surface of the substrate or between the outer layer and the inner layer of the substrate; and
forming a circuit on the surface of the substrate by disposing a conductive layer formed of a metal foil or a thin film on the surface and patterning the conductive layer to a desired configuration,
in which the foregoing each respective step is performed independently or the elements of each respective step are intermingled with one another for the purpose of achieving what is intended for by the foregoing respective steps, and further comprises the steps of;
attaching by adhesion a film-like separation film on a surface or both surfaces of the substrate before the foregoing step of forming holes, making the substrate and separation film almost in one-piece construction in the foregoing film attaching step, and then making the one-piece construction into a more solid one-piece structure intensely in the periphery of the through holes or non-through holes in the foregoing step of forming holes with a resulting prevention of the diffusion of connecting means to around the via holes. As a result, it is made possible for a high density and high reliability circuitry forming substrate to be realized.
A manufacturing method of circuitry forming substrates in a first aspect of the present invention comprises the steps of:
forming through holes or non-through holes on a plate-like or sheet-like substrate formed of a single material or a plurality of materials by irradiating an energy beam on the substrate;
forming a connecting means in the through hole or non-through hole formed in the foregoing hole forming step to connect electrically between the upper surface and the lower surface of the substrate or between the outer layer and the inner layer of the substrate; and
forming a circuit on the surface of the substrate by disposing a conductive layer formed of a metal foil or a thin film on the surface and patterning the conductive layer to a desired configuration,
in which the foregoing each respective step is performed independently or the elements of each respective step are intermingled with one another for
Chang Richard
McDermott & Will & Emery
LandOfFree
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