METHOD FOR APPLYING CONDUCTIVE LINES ON THE CASING OF MOBILE PHONE

Abstract: The present invention relates to a method for applying conductive lines, preferably power lines, on the plastic casing of a mobile phone. The phone casing (100) is covered by a first plastic material (200) rejecting deposition of a metal, and then covered by a second plastic material (300) in strings on the first plastic material corresponding to the desired conductive lines, wherein the second plastic material (300) accept the deposition of metal, after which the metal is deposited on the second plastic material (300).

Description: METHOD FOR APPLYING CONDUCTIVE LINES ON THE CASING OF MOBILE PHONE Field of invention The present invention relates to a method for applying conductive lines, preferably power lines, on a detail. Background of the invention In prior art it is known to apply conductive layers on mobile phone casings by means of a moulding method, which layers are used for EMI-shielding. However, in prior art it is not mentioned that a moulding method could be used for the purpose of distributing electric power lines to various components on a PCB. which is positioned inside this casing. In situations where e. g. large current pulses occur, such as in a cellular phone, and where these current pulses must pass close to other circuitry if the distribution must take place on the PCB, the pulses may create an electromagnetic interference (EMI) in other circuitry. This unwanted EMI could be avoided by implementing the power lines in the casing. An object of the present invention is to overcome this drawback and apply conductive circuit lines, preferably power lines, on the casing of a mobile phone by means of a moulding method. Summary of the disclosure The above object is achieved by means of a method as claimed in claims 1 and 6, respectively. An advantage with the inventive method is that it could be used generally to distribute the power (both supply and return lines) to a PCB that is assembled into a plastic casing. It saves space on the PCB, allows for wider lines (having a lower resistance), and can also move the power lines physically away from the PCB, reducing eventual noise problems. Other features of the invention are set out in the claims. Brief description of the drawings The present invention will now be described in more detail with reference to preferred embodiments of the present invention, given only by way of examples, and illustrated in the accompanying drawings in which: Figure 1 discloses conductive lines on a plastic casing according to the invention; and Figure 2 discloses a plastic board applied with two different plastic materials. Detailed description of an embodiment of the invention The current surges due to the GSM transmission bursts is known to create a "hum"- noise in the phone. The reason for this "hum"- noise is that the power lines from the battery to the PA-unit passes close by electro-acoustical devices, where the pulsating electro-magnetic field created by the current surges is inductively coupled into the electro-acoustical devices. The purpose of the invention is to avoid this inductive coupling by moving the power lines away from the electro-acoustic devices, and this is done by implementing the power lines, from battery to PA-unit, in the front casing by using what is called double moulding technology. If it is possible to separate both supply and return lines, then the magnetic field could be further reduced by the interference of the two opposite directed currents. Double moulding is a technology where two (or even three) different plastic materials can be used consecutively in the same moulding machine. It is possible to select plastic materials so that one accepts deposition of copper and the other does not. Then if a copper deposition process follows the double moulding process, it is possible to create a pattern of copper conductors on the plastic material. This technology is used by companies such as Nolato Mobile. It should be realised that this double moulding process could be used for creating an arbitrary conductive circuit pattern on a PCB or on the inside of a mobile phone casing. In figure 2 a process for creating a conductive circuit on a plastic board 100 is disclosed. The board is first covered by a first plastic material 200, which does not accept deposition of copper. Then, a nozzle applies a second plastic material 300, accepting deposition of copper, in strings corresponding to desired conductive circuit on the first plastic material. During deposition of copper, the copper will only be accepted by the second plastic material 300, whereby the conductive circuit is achieved. The connection between the double moulded conductive structure on the plastic 100 and the battery or the PCB can be seen in figure 1.One connection is a plating area for direct contact to a pad on the PCB 110. Another connection is diving-pins 120 and yet another connection is self threaded screws 130. It would be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential character thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence thereof are intended to be embraced therein.

Claims: CLAIMS 1. A method for applying conductive lines (400) on a detail (100), characterised in that a double moulding technology is used for applying the conductive lines on the detail. 2. A method as claimed in claim 1, characterised in that the detail is a mobile phone casing or a PCB. 3. A method as claimed in claims 1 or 2, characterised in that the detail (100) is covered by a first plastic material (200) rejecting deposition of a metal, and then covered by a second plastic material (300) in strings on the first plastic material corresponding to the desired conductive lines, wherein the second plastic material (300) accepts the deposition of metal, after which the metal is deposited on the second plastic material (300). 4. A method as claimed in any of the preceding claims characterised in that the conductive lines are power lines. 5. A method as claimed in any of the preceding claims characterised in that the connection between the conductive lines on the detail (100) and a PCB inside e.g. a mobile phone casing is achieved by means of a plating area for direct contact (110), diving pins (120) or self-threading screws (130). 6. A method for applying a conductive circuit pattern on a detail (100), characterised in that the detail is the inside of a mobile phone casing i.e. the plastic casing.

Inventors: BJOERKENGREN ULF, OLSSON MATS, BJOERKENGREN, ULF, OLSSON, MATS
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1999
Main classification: H05K3
IPC codes: B29D31, H04M1, H05K3, H05K5