JPH05190737A - Leadframe - Google Patents

Abstract

PURPOSE:To provide a leadframe which can easily be brazed to a ceramic substrate without positional displacement or deformation occurring at the time of the brazing. CONSTITUTION:Leadframes 10 and 20 are constituted by forming a plurality of L-shaped leads 12 and 22 on the inner side surface of two opposite sides of rectangular or square tie bars 11 and 21. These two leadframes 10 and 20 are laid one over the other at right angles relative to each other. With these leadframes arranged in this manner, when a ceramic substrate 1 is subjected to silver brazing, a flat package without deformation or positional displacement is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame used for manufacturing a lead bending type quad flat package (QFP).

[0002]

2. Description of the Related Art A QFP type flat package is shown in FIG.
The lead frame 2 is silver-brazed to the metallized terminals formed on the four sides of the ceramic substrate 1 as shown in Fig. 5, and the lead frame for this is L-shaped on one side of the tie bar 3 as shown in Fig. 5. The one provided with a large number of bent lead portions 4 is used.

In such a conventional lead frame, the four metal pieces are individually brazed to the metallized terminals of the ceramic substrate 1, so that the lead frame 2 is misaligned with respect to the ceramic substrate 1. There are problems that it is likely to occur, that the strength of each lead frame 2 is small and that it is easily deformed, and that silver brazing is individually performed on the four sides, so that it takes time to attach the brazing material. Although it is conceivable to integrate these lead frames, if the lead portions 4 are provided near the corners of the ceramic substrate 1 as shown in FIG. . That is, when the metal plate is punched out by stamping, since the lead portion 4 is in a state of extending in a plane, the tips of the lead portions 4 on the two sides that sandwich the corner portion overlap each other, making it impossible to take the material. .

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art by facilitating brazing to a ceramic substrate without misalignment and less deformation during and after brazing. It was completed to provide a lead frame.

[0005]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, has a structure in which a large number of bent lead portions are formed inside two opposite sides of a quadrilateral tie bar. It is characterized in that the lead frames are stacked orthogonally to each other.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the embodiments shown in FIGS. 1 and 2 show the first embodiment, in which 10 is a first lead frame and 20 is a second lead frame. In each lead frame, a large number of lead portions 12 and 22 bent in an L-shape are integrally formed on the inner sides of the two opposite sides of the quadrilateral tie bars 11 and 21. In the embodiment, the tie bars 11 and 21 are rectangular, and the lead portions 12 and 22 are formed inside the long sides thereof. When the lead portions 12 and 22 are formed on the two opposite sides in this way,
Even when the lead portion is flatly extended during stamping, there is no possibility that the tips of the lead portions will overlap with each other.

As shown in FIG. 2, in the present invention, the two lead frames 10 and 20 facing each other in a state where these two lead frames 10 and 20 are stacked perpendicularly to each other.
The lead portions 12 and 22 respectively formed on the sides are brazed with silver to the metallized terminals on the four sides of the ceramic substrate 1. At this time, since the first lead frame 10 on the upper side is lifted by the thickness of the plate at the portion where both the lead frames 10 and 20 cross each other, the lead portion bent in the L shape is formed.
When the heights of 12 and 22 are the same, the heights are displaced from the metallized terminals of the ceramic substrate 1. Therefore, in the first embodiment, as shown in FIG. 1, the step 13 corresponding to the plate thickness is provided at the portion where the tie bar 11 of the upper lead frame 10 crosses the tie bar 21 of the lower lead frame 20. Avoiding the problem. Reference numerals 14 and 24 are positioning holes.

In the second embodiment shown in FIG. 3, the tie bars 11 and 21 of the two lead frames 10 and 20 have a square shape, and when these are orthogonally overlapped with each other, the tie bars are overlapped.
11 and 21 will be entirely overlaid. In this case, the step 13 corresponding to the plate thickness cannot be provided as in the first embodiment. Therefore, the height of the lead portion 22 of the lower lead frame 20 is set to the height of the lead portion 12 of the upper lead frame 10. It is higher than the thickness by the thickness of the plate. In any of the embodiments, silver brazing is preliminarily bonded to the tips of the lead portions 12 and 22. Further, it is preferable that silver brazing is previously joined to the required portions of the tie bars 11 and 21 so that the lead portions 12 and 22 are brazed to the ceramic substrate 1 and the tie bars 11 and 21 are brazed at the same time.

[0009]

The lead frame of the present invention thus constructed has two lead frames 10 and 20 which are perpendicular to each other and overlap each other, and lead portions 12 to the metallized terminals on four sides of the ceramic substrate 1. Since the 22 tips can be brazed at the same time, compared to the conventional lead frame in which four sides are individually brazed,
It is possible to accurately perform the alignment between the 10 and 20, and between the lead frames 10 and 20 and the ceramic substrate 1. Further, since the lead frames 10 and 20 of the present invention are reinforced by the quadrilateral tie bars 11 and 21, there is no risk of deformation, and since it is not necessary to individually perform silver brazing on each side, silver brazing is possible. The man-hours of can be greatly reduced. Needless to say, the lead parts 12 and 22 are separated from the tie bars 11 and 21 after the brazing is completed.

[0010]

As described above, the lead frame of the present invention is formed by stacking two lead frames having the structure in which the lead portions are formed inside the two opposite sides so as to be orthogonal to each other. It is easy to braze the ceramic substrate without misalignment, and it is possible to prevent deformation due to handling during brazing and after brazing. Therefore, the present invention contributes greatly to industrial development as a lead frame that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a state in which the lead frame of the first embodiment of the present invention is brazed to a ceramic substrate.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

[Explanation of symbols]

 10 First lead frame 11 Tie bar 12 Lead section 13 Step 20 Second lead frame 21 Tie bar 22 Lead section

Claims (2)

[Claims] 1. A lead frame characterized in that two lead frames having a structure in which a large number of bent lead portions are formed inside two opposite sides of a quadrilateral tie bar are stacked orthogonally to each other. . 2. The tie bar has a rectangular shape, the lead portion is formed inside the long side thereof, and a step corresponding to the plate thickness is formed at a portion where the tie bar of the upper lead frame crosses the tie bar of the lower lead frame. The lead frame according to claim 1, wherein