Patent Application
20080048695
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A circuit substrate i according to an embodiment of the present invention is for forming a plurality of electric circuits that each have a different function on a single substrate 10.
For example, a circuit substrate like the circuit substrate 1 is used for formation of a circuit of a digital television broadcast receiving apparatus.
More specifically, a digital television broadcast receiving apparatus is configured from a plurality of electric circuits, such as an intermediate frequency transformer circuit that transforms high-frequency signals received from an antenna into intermediate frequency; a digital demodulator circuit that demodulates signals output from a transformer circuit to transport streams; and a video/audio processing circuit for extracting video signals and audio signals from compressed digital signals; and the circuit substrate 1 according to this embodiment is used in order to realize a circuit configured from these electric circuits on a single substrate.
Circuit blocks AA, BB, and CC are formed on the circuit substrate I so as to correspond to the respective electric circuits, and the circuit blocks AA, SB, and CC are connected to each other with a wiring metal pattern 15.
The circuit blocks AA, BB, and CC are configured from land patterns 12, a wiring pattern (not shown) for connecting the land patterns 12, and others. The wiring pattern is covered with a solder resist and thus protected.
Among the several wiring metal patterns 15 that connect the circuit blocks AA, BB, and CC to one another, a predetermined wiring metal pattern is separated at some midpoint of wiring so as to form two wiring metal patterns 15.
In determining the wiring metal pattern 1.5 to be separated, the wiring metal pattern 15, if it exists, from which electrical effects from other electric circuits arise during the test of electrical properties of the predetermined electric circuits (electric circuits formed by mounting predetermined electronic components on the circuit blocks AA, BB, and CC), is selected. Such a configuration can eliminate effects from other electric circuits or suppress such effects to a low level during testing of the predetermined electric circuits for their electrical properties.
A separated portion 16 is separated with a slit 17 of a predetermined width, and the separated two wiring metal patterns 15 are provided with exposed conductor portions 18 that are to be bridge-connected through soldering formed at the end portion of the respective separated portions 16. The exposed conductor portions 18 are formed by exposing conductors 20, and the surrounding areas are covered with solder resists 13.
Such a configuration, in which the wiring metal patterns 15 that connect the circuit blocks AA, BB, and CC to one another are separated, and the separated portion 16 is provided with the exposed conductor portions 18 formed at both ends of the wiring metal patterns 15, can simplify the work of connecting the circuit blocks by allowing bridging of the separated wiring metal patterns 15 through soldering. As a result, the time and cost required for manufacturing a circuit substrate can be reduced.
In addition, in a configuration in which the wiring metal patterns 15 that connect the circuit blocks AA, BB, and CC are separated, the location of separation is not limited and separation can be made at any location. Thus, the degree of freedom is not impaired in designing circuits of the circuit blocks AA, BB, and CC and in designing layout of the circuit blocks AA, BB, and CC.
In addition, both of the exposed conductor portions 18 are separated by a distance that can be bridged by applying a solder coating to both of the portions. This makes it possible to easily connect the separated portion 16 of the wiring metal patterns 15. Furthermore, the size of both of the exposed conductor portions 18 is designed so that the connection portion formed by connecting both of the exposed conductor portions 18 through soldering has sufficient strength.
For example, the exposed conductor portion 18 has a rectangular shape with a length d1 of 1.4 mm and a width d2 of 1.5 mm, and a slit width d3 between the exposed conductor portions 18 and 18 is 0.2 mm. The size of the exposed conductor portion 18 is not limited to this size, and is adjusted according to the surrounding wiring patterns or component layout.
In addition, both of or either of the exposed conductor portions 18 and 18 may have a shape with which a probe pin of a testing tester can come in contact. This configuration makes it possible to use the exposed conductor portions 18 of the wiring metal patterns 15 as testing pads for testing an electric circuit that has been formed by mounting the predetermined electronic components onto the circuit blocks AA, BB, and CC. In this case, since there is no need to newly provide a testing pad, the size of the circuit substrate 1 can be reduced by its size.
Furthermore, it is preferable to form solder layers 21 on the surface of the exposed conductor portions 18. The solder layers 21 are formed, for example, through solder printing or solder plating. This makes it possible to easily connect the separated portion 16 of the wiring metal patterns 15 through soldering.
Furthermore, it is preferable to form the solder layers of the exposed conductor portions 18 simultaneously with the task of forming the solder layers 21 to the land patterns 12 in a solder printing process of the circuit substrate 1. This can save labor of forming the solder layers 21 to the exposed conductor portions 18 in a newly provided separate process.
Hereinafter, a method for testing the circuit substrate I with electronic components mounted thereon will be described.
First, the predetermined electronic components are mounted onto each of the circuit blocks AA, BB, and CC, and each of the electric circuits is formed through reflow soldering to the circuit substrate 1. In this reflow process, the wiring metal patterns 15 that have been separated into two are not connected.
Testing of electrical properties is performed on each of the electric circuits in a state prior to connecting the separated portion 16 of the wiring metal patterns 15. In other words, electrical properties of each of the electric circuits can be tested with the electrical effects from the other electrical circuits eliminated since each of the electric circuits can be tested in a state in which the wiring metal patterns 15 that connect the circuit patterns AA, BB, and CC have been separated.
The testing of electrical properties may also be performed concurrently instead of separately on each of the electric circuits. This can reduce the testing time for the entire circuit.
Subsequent to the testing of electrical properties of each of the electric circuits, the separated portion 16 of the wiring metal patterns 15 is connected by soldering the separated portion 16. This electrically connects the electric circuits and completes the circuit.
The present invention may be embodied in various other forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all modifications or changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-229587 | Aug 2006 | JP | national |
