JP2004253714A - Wiring board with lead frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board which possesses leads excellent in high-frequency characteristics and is easily mounted on an external electric circuit board by an en-bloc solder reflow process. <P>SOLUTION: The wiring board with a leadframe possesses a dielectric substrate 1 for mounting a high-frequency component on its upper surface; signal line conductors 2, arranged on the upper surface of the dielectric substrate 1, with the signal electrodes of the high-frequency component electrically connected thereto; and signal leads 6 and ground leads 7 positioned on the lower surface of a wiring board which is arranged inside the dielectric substrate 1 and has a ground conductor layer 3 with slots 5 formed therein at a location where the ends of signal line conductors 2 face each other. In this leadframe, constituted of a first joining member 8 joining one end of each of them and a second joining member 9 joining the other end of each of them, the other ends of the ground leads 7 are electrically connected to a ground conductor lead out of the ground conductor layer 3, and the other ends of the signal leads 6 are electromagnetically coupled through the slots 5 with the ends of the signal line conductors 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board on which high-frequency components for microwaves and millimeter waves are mounted, and achieves both long-term reliability and high-frequency characteristics when a lead frame is attached to the wiring board and the wiring board is surface-mounted, so that the The present invention relates to a wiring board with a lead frame that can be easily mounted on an external electric circuit board by reflow.
[0002]
[Prior art]
In recent years, with the era of advanced information technology, it has been studied to utilize a high frequency signal used for information transmission from a microwave region of 1 to 30 GHz to a millimeter wave region of 30 to 300 GHz. Application systems using a millimeter-wave high-frequency signal such as described above have also been proposed.
[0003]
In an application system using such a high-frequency signal, if the frequency of the high-frequency signal is high, and there is an impedance mismatch in a high-frequency line forming the circuit, the high-frequency signal is reflected and the high-frequency signal is attenuated. In addition, the reflected wave has an adverse effect on other circuits. For this reason, in an application system using a high-frequency signal, the connection terminal structure of the wiring board on which the high-frequency component is mounted to the external electric circuit board must be externally mounted in order to suppress a change in impedance at the connection portion of the high-frequency wiring. A so-called ceramic wall package or metal wall package, which has substantially the same connection terminal structure as an electric circuit board, has been used.
[0004]
However, when mounting these packages on an external electric circuit board, the base of the package is made of metal in order to stabilize the ground potential of the package. Screw connection is used for mechanical connection, and wire bonding is used for electrical connection because the line conductor of the high-frequency line is exposed on the upper surface of the wiring board at the connection terminal to the external electric circuit board of the package. However, since it is necessary and the mounting is troublesome, there is a problem that the system becomes expensive.
[0005]
With respect to such a conventional package, there has been proposed a surface mount type package which can be mounted on an external electric circuit board by so-called batch reflow. For example, Japanese Patent Application Laid-Open No. 5-335432 discloses a metal lead frame including a ground plane and leads, and a conductor pattern having a shape corresponding to the shape of the metal lead frame formed on the surface. A circuit component is mounted on the front surface, and a conductor pattern of a shape corresponding to the shape of the metal lead frame is formed on the back surface. A wiring board comprising: a circuit board connected to a conductor pattern formed on a back surface via a conductor in the back surface, the back surface being bonded to a surface of a metal lead frame; and a metal cap covering the circuit board. A package structure having a configuration in which a lead frame is joined to the package structure is disclosed.
[0006]
Surface mounting using such a lead frame is excellent in long-term reliability of mounting because the lead frame can deform and absorb stress due to heat or external force. However, on the other hand, considering the deformation of the leads during assembly, the gap (interval) between the adjacent leads cannot be made very small, and therefore, the impedance of the leads for high-frequency signals can be set to a desired value. There is a problem that the high-frequency characteristics may be poor due to the failure.
[0007]
FIG. 2 is an assembly process diagram of the package structure disclosed in Japanese Patent Application Laid-Open No. 5-335432. According to the assembly process shown in FIG. 2, the metal lead frame 52 is joined on the insulating substrate 54, and the circuit board 56 is joined thereon. The metal lead frame 52 is supported by an outer peripheral frame during assembly, as shown in FIG. The ground plane of the lead frame 52 is connected from one outer frame to the opposing outer frame, and is stably supported by the outer frame. On the other hand, the signal leads of the metal lead frame 52 have a shape protruding from the outer peripheral frame, and are easily deformed. Therefore, the gap between the lead and the ground plane needs to be wide so as not to cause a short circuit even if the lead is deformed. For this reason, in this package structure, the gap between the lead and the ground plane is widened in order to secure the yield of the package assembly, and as a result, the impedance of the lead tends to increase. If the impedance of the internal wiring of the package is small, impedance mismatch will occur at the lead part, and if the signal to be handled is high frequency, the high frequency signal will be reflected at the lead part. there were.
[0008]
[Patent Document 1]
JP-A-5-335432
[Problems to be solved by the invention]
In order to solve such a problem, it is conceivable that the tip of the lead is connected to the ground plane, and the lead is more stably supported by the outer peripheral frame and the ground plane.
[0010]
However, if the lead supported by the outer frame is also connected to the inner ground plane in a wiring board with a lead frame used in a conventional package, the lead that should function as a signal conductor is short-circuited to ground. There is a problem that high-frequency signals cannot be transmitted depending on the type of lead.
[0011]
The present invention has been devised in view of the problems in the conventional technology as described above, and its object is to provide a high-frequency characteristic with good leads, and to facilitate mounting on an external electric circuit board by batch reflow. An object of the present invention is to provide a wiring board with a lead frame that can be used.
[0012]
[Means for Solving the Problems]
A wiring board with a lead frame according to the present invention includes a dielectric substrate on which a high-frequency component is mounted on an upper surface, and a signal which is disposed on the upper surface of the dielectric substrate and in which signal electrodes of the high-frequency component are electrically connected. A signal lead and a signal lead on a lower surface of a wiring board including a line conductor for use and a ground conductor layer provided inside the dielectric substrate and having a slot formed at a position where an end of the signal line conductor faces the end. A lead frame having a grounding lead, one end of which is connected by a first connecting member, and the other end of which is connected by a second connecting member, is connected to the other end of the grounding lead by the grounding. In addition to being electrically connected to a ground conductor derived from the conductor layer, the other end of the signal lead is joined to the end of the signal line conductor via the slot so as to be electromagnetically coupled. Is to be
[0013]
ADVANTAGE OF THE INVENTION According to the wiring board with a lead frame of this invention, the signal line conductor arrange | positioned at the upper surface of a dielectric substrate, and the slot arrange | positioned inside a dielectric substrate and the position where the edge part of a signal line conductor faces are opposed. A signal lead and a ground lead are provided on the lower surface of the wiring board having the formed ground conductor layer, and one end thereof is connected to the first connection member, and the other end is connected to the second connection member. Is joined so that the other end of the ground lead is electrically connected to the ground conductor derived from the ground conductor layer, so that the signal lead is connected to the first and second connecting members. It is supported and does not deform during the manufacturing process, and the gap between the signal lead and the ground lead can be set to be smaller than the conventional lead frame so as to have a desired impedance, and as a result, Re The frequency characteristic of the de part can be improved. The other end of the signal lead is short-circuited to the ground potential by being connected to the other end of the ground lead by the second connecting member. By connecting the lead frame to the lower surface of the dielectric substrate so that it is electromagnetically coupled to the end of the conductor and the slot formed inside the dielectric substrate, a high-frequency signal between the signal lead and the signal line conductor is formed. Can be satisfactorily transmitted.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a wiring board with a lead frame of the present invention will be described in detail with reference to the accompanying drawings.
[0015]
1A and 1B are diagrams illustrating an example of an embodiment of a wiring board with a lead frame according to the present invention. FIG. 1A is a top view, FIG. 1B is a cross-sectional view, and FIG.
[0016]
In FIG. 1, 1 is a dielectric substrate, 2 is a signal line conductor disposed on the upper surface of the dielectric substrate 1, 3 is a ground conductor layer disposed inside the dielectric substrate 1, and 4 is a high-frequency line composed of these. 5 is a slot formed in the ground conductor layer, 6 is a signal lead, 7 is a ground lead, 8 is a first connecting member for connecting one end of the signal lead 6 and one end of the ground lead 7, and 9 is This is a second connecting member for connecting the other ends of the leads 6 and 7 to each other.
[0017]
In the example of the wiring board with a lead frame of the present invention, a microstrip line as a high-frequency line 4 is formed by the dielectric substrate 1, the signal line conductor 2, and the ground conductor layer 3. A slot 5 is formed in the ground conductor layer 3 inside the dielectric substrate 1 at a position where the end of the signal line conductor 2 faces, and is electromagnetically coupled to the end of the signal line conductor 2. .
[0018]
In the lead frame, one end of the signal lead 6 is connected to one end of the ground lead 7 by the first connecting member 8 and the other end is connected to the ground lead 7 by the second connecting member 9. Both ends of the signal lead 6 are supported by the first and second connecting members 8 and 9 and are stable, and are not deformed during the manufacturing process. From this, the gap between the signal lead 6 and the ground lead 7 adjacent thereto can be set smaller than before so that the lead portion has a desired impedance, and the gap due to impedance mismatch at the lead portion can be set. There is no reflection of the high frequency signal, and good transmission of the high frequency signal becomes possible. The other end of the signal lead 6 is short-circuited to the ground potential by being connected to the other end of the ground lead 7 by the second connecting member 9, but the other end is inside the dielectric substrate 1. Is connected by electromagnetic coupling to the end of the signal line conductor 2 via the slot 5 formed in the ground conductor layer 3 disposed in the antenna, so that a high-frequency signal between the signal lead 6 and the signal line conductor 2 is provided. Can be satisfactorily transmitted.
[0019]
As a dielectric material for forming the dielectric substrate 1, a ceramic material containing aluminum oxide, aluminum nitride, silicon nitride, mullite, or the like as a main component, or a glass formed by firing a mixture of glass, glass, and a ceramic filler is used. An organic resin-based material such as a ceramic material, an epoxy resin, a polyimide resin, a fluorine-based resin such as an ethylene tetrafluoride resin, and an organic resin-ceramics (including glass) composite material are used.
[0020]
As a conductor material for forming the signal line conductor 2 and the ground conductor layer 3, a metallized conductor containing tungsten, molybdenum, gold, silver, copper, or the like as a main component, or gold, silver, copper, aluminum, or the like as a main component A metal foil or the like is used.
[0021]
In particular, when a high-frequency component is mounted on a wiring board with a lead frame, it is desirable that the dielectric material forming the dielectric substrate 1 has a small dielectric loss tangent and can be hermetically sealed. In this case, as a particularly desirable dielectric material, an inorganic dielectric material selected from an aluminum oxide-based sintered body, an aluminum nitride-based sintered body, and a glass-ceramic sintered body can be mentioned. These are hard materials. If the dielectric substrate 1 is formed of such a hard material, the dielectric loss tangent is small and the mounted high-frequency components are hermetically sealed by joining a lid (not shown). Since it can be stopped, it is preferable in improving the reliability of the mounted high-frequency component. In this case, it is desirable to use a metallized conductor that can be co-fired with these dielectric materials from the viewpoint of hermetic sealing and productivity as the conductor material.
[0022]
The wiring board with a lead frame of the present invention is manufactured, for example, as follows. For example, when an aluminum oxide sintered body is used as the dielectric material of the dielectric substrate 1, first, an appropriate organic solvent and a solvent are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Then, the slurry is formed into a sheet shape by a doctor blade method or a calendar roll method to form a ceramic green sheet. Further, a metallizing paste is prepared by adding an appropriate solvent and a solvent to raw material powders such as a high melting point metal such as tungsten and molybdenum, aluminum oxide, silicon oxide, magnesium oxide and calcium oxide. Next, a through-hole for forming a through conductor such as a via conductor or a through-hole conductor is formed in the ceramic green sheet as necessary, and a metallizing paste is embedded in the through-hole by, for example, a printing method. Metallized into a conductor pattern of the signal line conductor 2 and a conductor pattern of the ground conductor layer 3 having the slot 5 on the ceramic green sheet, and a conductor pattern of the ground conductor led out from the ground conductor layer 3 to the lower surface of the dielectric substrate 1. Print the paste. When the dielectric substrate 1 has a laminated structure of a plurality of dielectric layers, the ceramic green sheets in which the metallized paste is embedded or printed are laminated, pressed and pressed, and heated at a high temperature (about 1600 ° C.). Baking. Then, a lead frame produced by punching or etching from a metal plate is connected to the lower surface of the dielectric substrate 1 by, for example, silver-copper brazing material, and the other end of the ground lead 7 is connected to the ground conductor derived from the ground conductor layer 3. (Not shown) and the other end of the signal lead 6 is electromagnetically coupled to the end of the signal line conductor 2 via the slot 5 of the ground conductor layer 3. . Finally, nickel plating and gold plating are applied to the surfaces of the conductors exposed on the surface, such as the signal line conductor 2 and the signal leads 6 and the grounding leads 7.
[0023]
The electromagnetic coupling of the signal line conductor 2 and the signal lead 6 via the slot 5 is not particularly limited. For example, as shown in FIG. Good. In this case, if the length from the center of the slot 5 to the open end of the signal line conductor 2 is set to approximately (2n-1) / 4 times the signal wavelength of the high frequency signal when n is a natural number, The standing wave generated by the combination of the traveling wave transmitted through the line 4 and the reflected wave reflected at the open end of the signal line conductor 2 has the strongest magnetic field at the portion facing the slot 5 of the high-frequency line 4. In addition, electromagnetic coupling from the high-frequency line 4 to the slot 5 via a magnetic field is best performed, and the high-frequency characteristics of signal transmission to the signal lead 6 can be improved.
[0024]
When the tip of the signal line conductor 2 is short-circuited, the length from the slot 5 to the short-circuit end of the signal line conductor 2 is approximately (n) of the signal wavelength of the high-frequency signal when n is a natural number. If set to -1) / 2 times, the standing wave resulting from the combination of the traveling wave transmitted through the high-frequency line 4 and the reflected wave reflected at the short-circuited end of the signal line conductor 2 is a slot of the high-frequency line 4 5, the magnetic field becomes the strongest in the portion facing the wire 5, the electromagnetic coupling from the high-frequency line 4 to the slot 5 via the magnetic field is performed best, and the high-frequency characteristics of signal transmission to the signal lead 6 can be improved.
[0025]
The size of such a slot 5 is approximately equal to the signal wavelength of the high-frequency signal when the length is n is a natural number so that the magnetic field coupled from the signal line conductor 2 to the slot 5 can be stably present. n-1) / 2 times. Further, the length of the slot 5 may be intentionally shifted from the above-mentioned length with respect to the center frequency of the high-frequency signal to be used, and the frequency band to be coupled may be expanded. The distance between the slot 5 and the end of the signal line conductor 2 and the distance between the slot 5 and the other end of the signal lead 6 are adjusted so that unnecessary high-order mode resonance does not occur between them. What is necessary is just to set it as 1/4 or less of the signal wavelength of a signal.
[0026]
It should be noted that the present invention is not limited to the above embodiments, and various changes may be made without departing from the spirit of the present invention.
[0027]
For example, FIG. 1 shows an example in which the high-frequency line 4 has a microstrip line structure formed on the upper surface of the dielectric substrate 1. However, a dielectric layer is further laminated on the dielectric substrate 1, A so-called triplate line structure in which an upper surface ground conductor layer is provided on the upper surface of the body layer so as to cover the signal line conductor 2 may be used. Further, a so-called coplanar line structure with a ground may be used in which conductors for grounding on the same plane are arranged on both sides of the signal line conductor 2 in the same plane as the signal line conductor 2 at predetermined intervals. Also in these line structures, the same effect can be obtained by making the positional relationship of the signal line conductor 2, ground conductor layer 3, slot 5, signal lead 6, etc. the same as in the example shown in FIG. .
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the wiring board with a lead frame of this invention, the signal line conductor arrange | positioned at the upper surface of a dielectric substrate, and the slot arrange | positioned inside a dielectric substrate and the position where the edge part of a signal line conductor faces are opposed. A signal lead and a ground lead are provided on the lower surface of the wiring board having the formed ground conductor layer, and one end thereof is connected to the first connection member, and the other end is connected to the second connection member. Is joined so that the other end of the ground lead is electrically connected to the ground conductor derived from the ground conductor layer, so that the signal lead is connected to the first and second connecting members. It is supported and does not deform during the manufacturing process, and the gap between the signal lead and the ground lead can be set to be smaller than the conventional lead frame so as to have a desired impedance, and as a result, Re The frequency characteristic of the de part can be improved. The other end of the signal lead is short-circuited to the ground potential by being connected to the other end of the ground lead by the second connecting member. By connecting the lead frame to the lower surface of the dielectric substrate so that it is electromagnetically coupled to the end of the conductor and the slot formed inside the dielectric substrate, a high-frequency signal between the signal lead and the signal line conductor is formed. Can be satisfactorily transmitted.
[0029]
As described above, according to the present invention, it is possible to provide a wiring board with a lead frame having leads having good high-frequency characteristics and which can be easily mounted on an external electric circuit board by batch reflow.
[Brief description of the drawings]
FIG. 1 is a view showing an example of an embodiment of a wiring board with leads of the present invention, wherein (a) is a top view, (b) is a cross-sectional view, and (c) is a bottom view.
FIG. 2 is an assembly process diagram showing an example of a conventional wiring board with a lead frame.
[Explanation of symbols]
1 dielectric substrate 2 signal line conductor 3 ground conductor layer 4 high frequency line 5 slot 6 signal Lead 7 for grounding Lead 8 for connecting first connecting member 9 for second connecting member

Claims (1)

A dielectric substrate having a high-frequency component mounted on an upper surface thereof, a signal line conductor disposed on the upper surface of the dielectric substrate and electrically connected to a signal electrode of the high-frequency component, and the dielectric substrate A signal lead and a ground lead are provided on the lower surface of a wiring board having a ground conductor layer in which a slot is formed at a position where an end of the signal line conductor is opposed to the signal line conductor. A lead frame in which one end is connected by a first connecting member and the other end is connected by a second connecting member, the other end of the ground lead is connected to a ground conductor derived from the ground conductor layer. A wiring board with a lead frame, wherein the wiring board is electrically connected and the other end of the signal lead is electromagnetically coupled to the end of the signal line conductor via the slot.

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