JP5025360B2 - Solder pre-coated substrate - Google Patents

Description

  The present invention relates to a pattern shape of a solder precoat substrate on which electronic components such as semiconductor elements are mounted.

  Conventionally, semiconductor integrated circuit elements such as IC and LSI, and optical semiconductor elements such as a semiconductor laser (LD) and a light emitting diode (LED) are hermetically sealed in a package for housing these electronic components, and various electronic devices. Used as a part of One form of such a package includes a solder precoat substrate on which a semiconductor element is mounted and a hollow cap component (LID) that is a lid. The solder precoat substrate is made of a ceramic such as an aluminum oxide sintered body and has an element mounting portion for mounting a semiconductor element on the upper surface thereof. A solder layer is provided in advance using a solder paste or the like on a square frame-like pattern formed so as to surround the element mounting portion.

In a package using a solder pre-coated substrate, generally, a semiconductor element is mounted on the element mounting portion, the electrode of the element is electrically connected to the wiring conductor of the substrate, and then the LID is thermocompression bonded to the upper surface of the solder layer of the frame pattern Then, a step of reflowing the solder to fix the LID to the substrate is performed. At this time, if there is a variation in the pattern width of the frame-like pattern, the height of the solder layer varies, and the reliability of hermetic sealing is lowered. In order to cope with such a problem, in Patent Document 1, by forming each corner of the frame-shaped pattern in an arc shape, the width of the frame-shaped pattern is made constant over the entire circumference and the height variation of the solder layer is suppressed. ing.
JP 2005-340444 A

  As described above, in a package using a solder precoat substrate, if the pattern width of the frame-shaped pattern varies, the height of the solder layer formed on the frame-shaped pattern varies, and the reliability of hermetic sealing is improved. There was a problem of lowering. The configuration of Patent Document 1 is effective when one frame mounting pattern surrounds one element mounting portion, but it has a plurality of device mounting portions, and the shape of the frame pattern surrounding each element becomes complicated. Then, it is difficult to deal with the configuration of Patent Document 1 alone.

  For example, by having a plurality of adjacent element mounting portions, each frame-shaped pattern shares a part of the substantially parallel side portions adjacent to each other, so that this shared side portion and each frame-shaped pattern side portion are If a branched trifurcated part is formed, the pattern width of the trifurcated part will be larger than the pattern width of the other side parts, and the height of the solder layer of the trifurcated part will become extremely high partially. Problem arises.

  The present invention has been made to solve the above-described problems. In a solder pre-coated substrate having a plurality of adjacent element mounting portions, a solder layer having a small height variation is formed, and the air gap between the lid and the lid is reduced. An object of the present invention is to provide a solder precoat substrate having excellent hermetic sealing reliability.

The solder pre-coated substrate according to the present invention has a pattern width mutually formed on the substrate so as to surround the adjacent first and second element mounting portions and the first and second element mounting portions, respectively. Equal first and second frame-shaped patterns and solder layers formed on the top surfaces of the first and second frame-shaped patterns are provided, and the first frame-shaped pattern and the second frame-shaped pattern are adjacent to each other. Shares at least a part of the substantially parallel sides, the side excluding the shared side of the first frame-like pattern, and the side excluding the shared side of the second frame-like pattern In the three-pronged portion serving as a branching point of the portion, a concave portion is provided in which a connecting portion between the outer peripheral edge of the first frame-shaped pattern and the outer peripheral edge of the second frame-shaped pattern enters the central direction of the three-pronged portion. .

  According to the present invention, the pattern width of the three-pronged portion can be made equal to the pattern width of the side portion excluding the three-pronged portions of the first and second frame-like patterns by the concave portion provided in the three-pronged portion. In addition, since a precoat solder layer having a small height variation can be formed over the entire circumference, it is possible to obtain a solder precoat substrate excellent in the reliability of hermetic sealing with the lid.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. 1 and 2 are a plan view and an enlarged plan view of a main part showing a pattern shape of a solder precoat substrate according to the first embodiment of the present invention. In the figure, the same parts are denoted by the same reference numerals. The solder precoat substrate in the present embodiment is provided with a first element mounting portion 2a and a second element mounting portion 2b adjacent to each other on the substrate 1, and a square frame so as to surround these element mounting portions 2a and 2b. The first frame-like pattern 3a and the second frame-like pattern 3b having the same pattern width are formed. Further, a precoat solder layer (not shown) for joining the substrate 1 and a hollow cap component (hereinafter referred to as LID) as a lid on the upper surfaces of the first and second frame patterns 3a and 3b. Is formed.

  The substrate 1 is made of a ceramic such as an aluminum oxide sintered body or glass ceramics, and is a wiring made of a metal material from the first and second element mounting portions 2a and 2b on the upper surface to the outer peripheral portion, side surface or lower surface of the upper surface. A conductor (not shown) is derived. On the first and second element mounting portions 2a and 2b, there are semiconductor integrated circuit elements such as IC and LSI, optical semiconductor elements such as LD and LED, or other electronic components (not shown) including various elements. Installed.

  Each of the first frame-shaped pattern 3a and the second frame-shaped pattern 3b having the same pattern width is formed in an arc shape so as to have a substantially uniform pattern width over the entire circumference. A precoat solder layer is formed on the top surfaces of the first and second frame-like patterns 3a and 3b. The precoat solder layer is formed by supplying a solder paste and reflowing the upper surfaces of the first and second frame patterns 3a and 3b.

  The electrodes of the electronic components mounted on the first and second element mounting portions 2a and 2b are electrically connected to the wiring conductor exposed on the first and second element mounting portions 2a and 2b via bonding wires or solder. Connected to. Furthermore, the electrode of the electronic component is connected to the external electric circuit by electrically connecting the other lead-out portion of the wiring conductor to the external electric circuit. Thereafter, LID (not shown) made of metal or the like is thermocompression bonded to the upper surface of the precoat solder layer of the first and second frame-like patterns 3a and 3b, and the solder is reflowed to fix the LID to the substrate. Is hermetically sealed.

In the present embodiment, the first frame-shaped pattern 3a and the second frame-shaped pattern 3b have a shared side portion 3c sharing at least a part of the substantially parallel side portions adjacent to each other. "Type". The branching point of the shared side 3c, the side excluding the shared side 3c of the first frame-shaped pattern 3a, and the side of the second frame-shaped pattern 3b excluding the shared side 3c is the three-pronged portion 4 It has become. As shown in FIG. 2, the three-pronged portion 4 has a connecting portion 32c between the outer peripheral edge 32a of the first frame-shaped pattern 3a and the outer peripheral edge 32b of the second frame-shaped pattern 3b. A concave portion 5 is provided in the direction.

  Thus, by providing the concave portion 5 in which the connection portion 32c between the outer peripheral edge 32a of the first frame-shaped pattern 3a and the outer peripheral edge 32b of the second frame-shaped pattern 3b enters the center 4a direction of the three-pronged portion 4, The pattern width of the trifurcated portion 4 is equal to the pattern width of the side portion excluding the trifurcated portion 4 of the first and second frame patterns 3a and 3b. Thereby, when a precoat solder layer is formed on the first and second frame-like patterns 3 a and 3 b including the three-pronged portion 4, it is possible to suppress a large pool of solder from being formed in the three-pronged portion 4. The height of the solder layer of the trifurcated portion 4 can be suppressed from becoming extremely high partially.

  Therefore, according to the present embodiment, the first and second element mounting portions 2a and 2b that are adjacent to each other, and the first frame-shaped pattern 3a and the second frame-shaped pattern 3b that surround them are adjacent to each other. In the solder precoat substrate in which the three-pronged portion 4 is formed by sharing at least a part of the parallel side portions, the pre-coating with small height variation is provided by providing the concave portion 5 which enters the center 4a direction of the three-pronged portion 4. A solder layer can be formed, and a solder precoat substrate excellent in the reliability of hermetic sealing with LID as a lid can be obtained.

Embodiment 2. FIG.
In the first embodiment, the recess 5 is provided in which the connecting portion 32c between the outer peripheral edge 32a of the first frame-shaped pattern 3a and the outer peripheral edge 32b of the second frame-shaped pattern 3b enters the direction of the center 4a of the three-pronged portion 4. Thus, the pattern width of the three-pronged portion 4 is set to be equal to the pattern width of the side portion excluding the three-pronged portion 4 of the first and second frame-like patterns 3a and 3b. In the second embodiment of the present invention, in the same configuration as that of the first embodiment, the diameter of the inscribed circle inscribed in the three-pronged portion 4 is further set to the first frame-shaped pattern 3a or the second frame-shaped pattern. The concave portion 5 is provided so as to be larger (about 1.1 times) than the diameter of the pattern inscribed circle inscribed in the side portions excluding the three-pronged portion 4 of 3b.

  The configuration of the solder precoat substrate in the present embodiment will be described with reference to FIG. Similar to the first embodiment, the three-pronged portion 4 is provided with a concave portion 5, and the inscribed circle 6 inscribed in the three-pronged portion 4 has an inner peripheral edge 31a and a second second in the first frame-shaped pattern 3a. Are in contact with three points of the inner peripheral edge 31b of the frame-shaped pattern 3b and the apex (connection portion 32c) of the recess 5. On the other hand, the pattern inscribed circle 7 that is inscribed in the side portion excluding the three-pronged portion 4 of the first frame-shaped pattern 3a is in contact with two points of the inner peripheral edge 31a and the outer peripheral edge 32a of the first frame-shaped pattern 3a. .

  In the present embodiment, the diameter 6a of the inscribed circle 6 that is inscribed in the three-pronged portion 4 is set to the inner side of the first frame-shaped pattern 3a (or the second frame-shaped pattern 3b) except for the three-pronged portion 4. It is designed to be larger than the diameter 7a of the pattern inscribed circle 7 in contact therewith. The ratio of the diameters is desirably about 1.1 times. In such a configuration, the solder is more stable in terms of surface free energy when it gathers in the three-pronged portion 4 having a larger diameter 6 a of the inscribed circle 6. Thus, a partial solder protrusion (not shown) corresponding to is formed. By providing such a solder convex portion, in the subsequent process of thermocompression bonding the LID to the upper surface of the precoat solder layer, the pressure is concentrated on the solder convex portion, and thermocompression bonding becomes easy.

  Specifically, when the ratio of the diameter of the inscribed circle 6 of the trifurcated portion 4 and the diameter of the pattern inscribed circle 7 of the side portion excluding the trifurcated portion 4 is designed to be about 1.1 times, the precoat solder at each location We have obtained data that the layer height ratio is about 1.2 times. This difference in the height of the precoat solder layer does not prevent the LID and the substrate 1 from being uniformly soldered over the entire circumference, but rather, as described above, the partial coating formed on the three-pronged portion 4 is partially prevented. Such a solder convex portion facilitates thermocompression bonding when the LID is fixed on the substrate 1 and provides good thermocompression bonding.

On the other hand, when the solder recess 5 is not provided in the trifurcated portion 4, the ratio of the diameter of the inscribed circle 6 of the trifurcated portion 4 to the pattern inscribed circle 7 of the side portion excluding the trifurcated portion 4 is 1. It becomes about 5 times, and the ratio of the height of the precoat solder layer in each part becomes about 1.7 times. If the ratio of diameters becomes too large in this way, the solder projections formed on the trifurcation 4 will exceed the appropriate height, making it difficult to solder the LID and the substrate 1 uniformly over the entire circumference. Good thermocompression bondability cannot be obtained.

  Therefore, the height of the solder protrusions is such that it does not prevent the LID and the substrate 1 from being uniformly soldered over the entire circumference, and a good thermocompression bondability can be obtained by the presence of the partial solder protrusions. It is desirable to design the depth of the concave portion 5, in other words, the diameter 6 a of the inscribed circle 6 of the three-pronged portion 4 so as to be high.

  According to the present embodiment, the first and second element mounting portions 2a and 2b that are adjacent to each other, and the first frame-shaped pattern 3a and the second frame-shaped pattern 3b that surround these are adjacent to each other and are substantially parallel to each other. In the solder precoat substrate in which the trifurcated portion 4 is formed by sharing at least a part of the side portion, the diameter of the inscribed circle inscribed in the trifurcated portion 4 is the first frame-shaped pattern 3a or the second frame. By providing the recess 5 so as to be larger (about 1.1 times) the diameter of the pattern inscribed circle inscribed in the sides excluding the three-pronged portion 4 of the pattern 3b, the same effect as in the first embodiment is obtained. In addition, the partial solder protrusion formed on the trifurcated portion 4 facilitates thermocompression bonding when the LID is fixed onto the substrate 1 and has an effect of obtaining good thermocompression bonding.

  In Embodiments 1 and 2 described above, the solder pre-coated substrate having two adjacent element mounting portions and having a frame-shaped pattern of “sun-shaped” has been described as an example. The number, shape, and arrangement of the shape patterns are not particularly limited, and the present invention can be applied to a case where there are a plurality of element mounting portions and the frame shape pattern surrounding these has a trifurcated portion.

  The solder precoat substrate according to the present invention can be used for an electronic component on which a semiconductor integrated circuit element such as an IC or LSI, or an optical semiconductor element such as an LD or LED is mounted and hermetically sealed.

It is a top view which shows the pattern shape of the solder precoat board | substrate by Embodiment 1 of this invention. It is a principal part enlarged plan view which shows the pattern shape of the solder precoat board | substrate by Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate, 2a 1st element mounting part, 2b 2nd element mounting part, 3a 1st frame shape pattern, 3b 2nd frame shape pattern, 3c shared edge part, 4 trifurcation part, 4a trifurcation part center ,
5 concave portion, 6 trifurcated inscribed circle, 6a diameter, 7 pattern inscribed circle, 7a diameter, 31a inner peripheral edge of first frame-shaped pattern, 31b inner peripheral edge of second frame-shaped pattern, 32a first frame-shaped The outer peripheral edge of the pattern, 32b The outer peripheral edge of the second frame-shaped pattern, 32c connection portion.

Claims (2)

  The first and second element mounting portions adjacent to each other on the substrate and the first and second elements having the same pattern width are formed in a square frame shape so as to surround the first and second element mounting portions, respectively. A frame-shaped pattern and a solder layer formed on the upper surface of the first and second frame-shaped patterns, wherein the first frame-shaped pattern and the second frame-shaped pattern are substantially parallel sides adjacent to each other. Sharing at least part of the portion, the side of the first frame-shaped pattern excluding the shared side, and the side of the second frame-shaped pattern excluding the shared side In the three-pronged portion that becomes a branching point of the portion, a concave portion is provided in which a connection portion between the outer peripheral edge of the first frame-shaped pattern and the outer peripheral edge of the second frame-shaped pattern enters the center direction of the three-pronged portion. A solder pre-coated substrate characterized by that.   2. The solder pre-coated substrate according to claim 1, wherein a diameter of an inscribed circle inscribed in the trifurcated portion is a side portion excluding the trifurcated portion of the first frame-shaped pattern or the second frame-shaped pattern. A solder precoat substrate, wherein the concave portion is provided so as to be larger than a diameter of an inscribed circle inscribed therein.

Images