Patent Application
20060154102
The present rehabilitation invention is related to a soft circuit substrate, and more particularly to a soft thin laminated substrate including one single alloy copper layer as the tie-coating of the copper foil.
A conventional soft circuit substrate is composed of a soft substrate and a conductive copper foil associated with the substrate. In conventional measure, the copper foil is adhered to the substrate by means of an adhesive. However, such measure often leads to problems of detachment, halogen flameproof agent, etc. In another traditional measure, a liquid plastic resin is directly painted over the copper foil and the substrate. After dried and solidified, the copper foil is integrally associated with the substrate. However, the above two measures can be hardly applied to those copper foils under 8 um. In addition, the adhesion force of the plastic resin between the copper foil and the substrate is insufficient. That is, when the copper foil conducts current, a temperature (generally below 150° C. ) will more or less rise. Moreover, the material of the copper foil is different from plastic resin. Accordingly, the thermal strain (mechanical tension ) of the copper foil is different from that of the plastic resin under such temperature. As a result, blister or lifting or peeling of the coating of the soft circuit substrate will take place.
Recently, sputtering technique has been applied to manufacturing of soft circuit substrate. For example, Taiwanese Patent Publication No. 519860 discloses a method for manufacturing soft circuit substrate and a product thereof.
In the above soft circuit substrate structure, the chromium attaching layer, nickel-chromium alloy attaching layer and copper attaching layer all serve as tie-coatings of the copper foil. By means of the tie-coating, the polymer film with quite different physical properties can be tightly bonded with the copper foil.
However, in the above structure, the multiple tie-coatings lead to increment of manufacturing time and complicate the manufacturing procedure. As a result, the manufacturing cost is much higher. Moreover, the tie-coatings will increase the impedance of the material. For example, the impedance of chromium is more than ten times the impedance of copper and the impedance of nickel is more than four times the impedance of copper. All the above problems should be solved.
It is therefore a primary object of the present invention to provide a soft thin laminated substrate in which only an alloy copper layer is disposed between the plastic substrate and the copper foil as the tie-coating of the copper foil. The copper foil can tightly attach to the alloy copper layer to tightly associate with the plastic substrate. When the temperature rises, the coating will not blister or peel. Therefore, the using life is prolonged. Also, the cost is reduced and the manufacturing procedure is simplified.
According to the above object, the soft thin laminated substrate includes: a plastic substrate; an alloy copper layer overlaid on the plastic substrate, the alloy copper layer having a thickness within 10˜10000 angstroms, the alloy copper layer being an alloy of 0.1%˜99.95% copper metal and at least one of nickel, chromium, manganese, molybdenum, iron and phosphorus; and a copper foil overlaid on the alloy copper layer.
The present invention can be best understood through the following description and accompanying drawings wherein:
Please refer to
The plastic substrate 1 can be made of one of polyimide (PI ), PET, PC, PMMA, etc. With polyimide exemplified, such material has excellent electrical properties, anti-chemical properties and highest heat resistance among polymer materials. Therefore, the thermal strain can be minimized.
The alloy copper layer 2 is disposed on the plastic substrate 1 by way of vacuum physical coating. The thickness of the alloy copper layer 2 is within 10˜10000 angstroms. The alloy copper layer 2 is an alloy of 0.1%-99.95% copper metal and at least one of nickel, chromium, manganese, molybdenum, iron and phosphorus. The added metal has excellent electric conductivity. Preferably, the added metal will not increase the impedance of the alloy copper layer 2.
The copper foil 3 disposed on the alloy copper layer 2 by way of vacuum physical coating is composed of 10%-99.95% copper metal and at least one of nickel, chromium, manganese, molybdenum, iron and phosphorus.
The vacuum physical coating can be thermal evaporation, electron beam evaporation, DC magnetron sputter, RF magnetron sputter, ion beam sputter, molecular beam epitaxy (MBE ) or plasma enhanced CVD. The alloy copper layer 2 of the present invention contains pure copper molecules. By means of the better electric conductivity of pure copper molecules, the bonding strength of the copper foil 3 can be enhanced. Moreover, by means of those low-impedance materials such as nickel, chromium, manganese, molybdenum, iron and phosphorus, the electric conductivity of the alloy copper layer 2 will not be greatly reduced.
In the soft thin laminated substrate structure of the present invention, the alloy copper layer 2 serves as a tie-coating of the copper foil 3. The alloy materials of nickel, chromium, manganese, molybdenum, iron and phosphorus in the alloy copper layer 2 have better bonding strength to plastic material so that the alloy copper layer 2 can be more firmly bonded with the substrate 1. Also, the copper foil 3 can tightly attach to the alloy copper layer 2 to associate with the plastic substrate 1. It is known from an actual pull test, the peel strength of the soft thin laminated substrate of the present invention is up to 0.65 kg/cm2. Accordingly, the structure of the present invention can truly well bond the plastic substrate 1, alloy copper layer 2 and copper foil 3 with each other. Moreover, the plastic substrate 1 of the present invention has better thermal strain and the plastic substrate 1, the alloy copper layer 2 and the copper foil 3 are better bonded with each other. Therefore, when the temperature rises to 150° C., the coating of the present invention is uneasy to blister or lift or peel. Therefore, the using life of the present invention is prolonged.
In conventional technique, the tie-coating is formed of a three-layer structure, that is, a chromium attaching layer, a nickel-chromium alloy attaching layer and a copper attaching layer. In comparison with the prior art, the soft thin laminated substrate structure of the present invention only includes an alloy copper layer as the tie-coating for tightly bonding the plastic substrate 1, alloy copper layer 2 and copper foil 3 with each other. Therefore, the present invention can achieve double effects of decrement of cost and simplification of manufacturing procedure.
The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.
