Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1996-01-18
2001-04-17
Sough, Hyung-Sub (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C029S827000, C029S855000, C427S096400, C428S209000
Reexamination Certificate
active
06218628
ABSTRACT:
FIELD OF THE INVENTION
The invention is in the field of the manufacture of printed circuit boards and foil circuit boards and relates to a method for the manufacture of printed circuit boards, foil circuit boards and semifinished products for such circuit boards and relates to printed circuit boards, foil circuit boards and semifinished products for such circuit boards manufactured according to the method.
BACKGROUND OF THE INVENTION
In many fields of modern electronics circuit carriers such as e.g. printed circuits are mechanically and also electrically connected to integrated circuits (ICs) or other active and/or passive electronic components. This normally takes place by means of plug and socket or soldered connections. The connections for the components are in many cases shaped as soldered or plug connection leads and are mechanically fixed by means of the components to the printed circuit board or foil circuit board and electrically connected thereto,, To an increasing extent unhoused components (“bare” ICs) are directly applied to circuit boards or connecting substrates. The electrical connections between the component and connecting substrate are provided either by wire bonding, TAB or flip clip methods. These assembly methods are now very important, due to the constantly rising complexity of electronic functions, because they can lead to space and cost savings.
However, usually such circuits are designed in the form of modular components, which in principle represent higher Integrated components. However, such modules must be mechanically and electrically connected to the printed or foil circuit board, so that the modular component once again requires leads. The latter can be constructed in various ways, but are generally applied as pre-fabricated, comb-like structured leads and are in this way soldered to the circuit.
Circuits in foil circuit boards are often used as flat band cables and can also be provided with leads in accordance with the above-described method, but in general plugs are soldered on and can be electrically and mechanically connected to counterplugs. It is characteristic of such connections that a first element (modular component, printed or foil circuit board) and a second element (printed or foil circuit board, etc.) must be mechanically and electrically interconnected. This means that for the formation of an electrical connection of a single current path two electrical connection points are required, which not only involves costs, but also has a negative influence on reliability. In addition, the connection point cannot be utilized in an optimum manner. The conductor pattern, all the current paths, insulating areas, openings and plated-through holes must be adapted for application purposes. For example current paths are mechanically reinforced or are modified with regards to their physical extension in the vicinity of the application of the connecting means. For assembly reasons leads are often made much thicker than necessary. Soldering pads are frequently made wider than the current paths, etc. passed up to them. These precautions require methods with in part, complicated processing steps and take up time and space.
Circuits with more complex contours are, according to the prior art, manufactured by known manufacturing methods with material and known means for the individual stages, so that these circuits have readily manipulatable shapes, i.e. for circuit boards they comprise rectangular or square material pieces or with foil circuit boards quasi-endless material from a reel. Only in one of the last operations are the circuits milled or punched out from the substrate in accordance with their definitive contours. However, this final cutting to size places limits on the complexity of the contours. The more complex the shape and the smaller the individual dimensions of the printed and foil circuit boards to be produced, the more difficult and complicated said final cutting to size.
With smaller numbers, where the manufacture of punching tools is not worthwhile, cutting out takes place by milling. If thin foil material is to be milled, so as to prevent any displacement upstream of the tool, it is necessary to ensure that fixing occurs between rigid carrier materials. The carrier materials are also milled and constitute an expensive auxiliary material. Despite the carrier materials used the precision of the milling step is limited and in particular no very narrow areas can be milled, because milling is a sequential process and the displacement of the material increases if successively close together milling cuts are made. A further problem is the fraying of the milled edges, which involves expensive, manual after-work. Punching is advantageously used for larger numbers. The tool for such a punching step can e.g. be a knife-like, ground, flexible steel band inserted in a recess of a base plate, so that a randomly shaped recess can be produced. However, it is scarcely possible to obtain radii of curvature below approximately 3 mm. In addition, the service life for such tools is approximately 1000 strokes and the accuracy of cut is at most ±0.2 mm. Better punching precisions can be obtained with hardenable steel tools. Such tools are made by spark erosion, but are much more expensive than the aforementioned steel band or strip punching tools. In any case a complicated and expensive punching machine is required, so that the final cutting to size of circuits by punching is very expensive.
It would be desirable to so integrate the application of mechanical structures or patterns for connecting means and contours such as leads, plugs, soldering pads, holes, grooves, etc. in printed and foil circuit boards, that the necessary costs and space consumption are kept to a minimum. It must be possible to use known and proven processing steps, as well as corresponding tools and apparatus.
SUMMARY OF THE INVENTION
An object of the invention is to provide a method for the manufacture of printed circuit boards, foil circuit boards and semifinished products for such circuit boards, where the structures or patterns for connecting means and contours are applied during the manufacture of the foil and printed circuit boards in the substrate of the latter and do not have to be subsequently made.
The invention is based on the observation that in insulating layers and substrates of printed and foil circuit boards not only can simple structures such as blind- or through-holes be formed by plasma etching, but also complicated structures. This offers new degrees of freedom in the design of printed and foil circuit boards.
This innovation is the integration of the manufacture of functionally outwardly directed connecting means and contours around conductor patterns in the substrate in the manufacture of conductor patterns or internal structures of the printed or foil circuit boards. The connecting means are e.g. used for power supply purposes, for connection to other circuits or for connection to other areas of the same conductor pattern and the contours serve as prefabricated fragments for separating conductor patterns from the substrate. Thus, there is an integration of the connecting means and contours in or on the substrate in the structuring of the conductor pattern and relates to the structuring of current paths, insulating areas, openings, plated-through holes, webs, grooves, etc.
In the method according to the invention, three-dimensional structures such as leads, matching connecting openings with current paths, flexible leads and shielded cables as connecting means and openings, webs and grooves as contour lines are produced during the photochemical structuring of the printed and foil circuit boards and their semifinished products. In the sense of an advantageous, very tight surface-covering conductor pattern, the connecting means and contours for the same are incorporated into the conductor pattern production so that simultaneously or in the same method and using identical or similar marks can be manufactured like them from preliminary products.
The connecting
Martinelli Marco
Schmidt Walter
Dyconex Patente AG
Rankin, Hill Porter & Clark LLP
Sough Hyung-Sub
LandOfFree
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