JPH0348452A - Two-terminal surface mount semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to be subjected to surface mount of the title device on a printed wiring board with good stability at a little manufacturing cost by a method wherein a press working is performed on the point parts of lead pins to mold flat soldered leg parts and at the same time, the tabular surfaces of the soldered leg parts are arranged properly on the same surface and each lead pin led out from both ends of a package is molded in a hairpin type. CONSTITUTION:Each electrode header 6a is previously press molded on one end of each lead pin 6 and the two lead pins 6 are coaxially arranged on both sides of a semiconductor chip 1 holding the chip 1 in the center between the pins 6 and are bonded to the chip 1 by soldering or the like. This assembled body is inserted in a molding die, a resin package is molded, the ends of both of the pins 6 led out from the package 2 are cut in a prescribed length, the point parts of the pins 6 are pressed, flat plate-shaped soldered leg parts 6b are molded and are arranged properly on the same surface on the side of the lower surface of the package 2 and the pins 6 led out from the package are subjected to forming in a hairpin type facing inward. Moreover, in order to increase solderability, a metal covering layer, which is 1 to 10mum in film thickness and is excellent for soldering, is applied on the point parts of the pins.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a two-terminal surface mount semiconductor device such as a semiconductor diode, and particularly to a lead terminal structure thereof. [Prior art] As the two-terminal surface mount type semiconductor device mentioned above, FIG.
As shown in Fig. 11, a structure in which a semiconductor chip is mounted on a lead frame and sealed with resin is conventionally known. In the figure, 1 is a semiconductor chip, 2 is a resin puff cage that seals the periphery of the semiconductor chip l, 3 is a lead piece pulled out from the pan cage 2, and 4 is an auxiliary lead piece. A method of manufacturing a semiconductor device having such a structure will be explained with reference to FIG. 11. First, as shown in FIG. 11, a semiconductor chimp 1 is mounted directly at a predetermined position on a lead frame 5 which is press-molded into a desired shape from a flat metal plate, and then Another auxiliary lead piece 4 is soldered and connected between the semiconductor chip l and the lead 5 as shown in the figure. Next, as shown in the same figure (bl), after sealing the periphery of the semiconductor chip 1 and molding the resin package 2 by transfer molding, the lead frame 5 is further canted along the dashed line to form the one shown in the same figure (C). Next, as shown in the same figure (dl), form the lead pieces 3 pulled out from both ends of the bankage 2, and form them into a hairpin shape toward the bottom of the package 2 so that the tips are aligned on the same plane. Molding. When mounting such a semiconductor device on a printed wiring board,
The lead piece 3 is mounted on the board with the tip facing downward, and surface-mounted using a method such as reflow soldering.

[Question B that the invention attempts to solve]

By the way, in the surface mount type semiconductor device of the conventional structure described above, the manufacturing process is difficult. There are also the following difficulties in handling the product. That is, 11) Since the structure uses a custom-made lead frame 5 and mounts the semiconductor chip l thereon, the manufacturing cost of the lead frame including the mold is high, and the cost is high. (2) ) Mount the semiconductor chip 1 on the lead frame with the lead piece 3
In order to connect to the lead frame 5, an auxiliary lead piece 4. A soldering process is also required. 《3) During the manufacturing process, individual semiconductor devices are mounted on side rails on a lead frame. Because they are connected together by tie bars, it is not possible to conduct individual characteristic tests on the lead frame before it is cut. The present invention has been made in consideration of the above points, and an object of the present invention is to provide a two-terminal surface-mounted semiconductor device that can be manufactured at low cost by solving the problems of the conventional structure described above. Means for Solving CRB] In order to solve the above 1jlM, a two-terminal surface mount type semiconductor device according to the present invention includes a semiconductor chip sealed in a package, and a semiconductor chip sealed in a package from both ends of the package with the semiconductor chip sandwiched in the center. It consists of an assembly with a lead pin pulled out on pongee.
In addition, the tips of the lead pins are pressed to form flat soldering legs, and the plate surfaces of the core soldering legs are aligned on the same plane, and each lead pin pulled out from both ends of the package is shaped into a hairpin shape. I will give you a precept.
In addition, in order to improve the solderability when surface-mounting the semiconductor device of the above structure onto a printed wiring board, a layer thickness of 1 to 10 μm is applied to the surface of the lead pin before pressing the tip of the lead pin. A metal coating layer with good solder adhesion can be formed. Further, for the same purpose, after pressing a soldering leg on the tip of a lead pin, a metal coating layer with good solder adhesion can be formed on the surface of the soldering leg. [Function] With the above structure, without using a lead frame,
Similar to the conventional pongee lead type semiconductor device, a lead terminal structure that allows surface mounting is obtained by using a nine-wire glued bin for the leads. In particular, the tip of the lead pin is pressed to form a flat plate-shaped soldering leg, allowing stable surface mounting on the printed wiring root. In addition, before pressing the tip of the lead pin in the above structure, a metal material with good solder adhesion and having a sufficient thickness of 1 to 10 μm is applied to the surface of the lead pin. For example, by applying a metal coating layer such as solder or silver,
Even if press processing is applied to the tip of the lead pin after that, the gold is still intact! The AN does not peel off and the underlying metal of the lead pin is exposed, and soldering can be performed with good adhesion to the printed wiring board. Note that this metal coating layer can be easily formed by surface treatment such as dipping or plating. Furthermore, if a metal coating layer with good solder adhesion is formed on the surface of the soldering leg after pressing the soldering leg at the tip of the lead pin, soldering can be performed without being affected by the pressing process. The metal coating layer can be stably adhered to the legs, and it can be soldered with good adhesion to the printed wiring board. [Examples] Examples of the present invention will be described below based on the drawings. first,
1 to 3 show the structure of an embodiment of the present invention. In the figures, 1 is a semiconductor chip, 2 is a resin puff cage that seals the periphery of the semiconductor chip 1, and 6 is a resin puff cage with the semiconductor chip 1 in the center. These are nine-line lead pins that are sandwiched and pulled out from both ends of the pan cage 2 on the same side. In addition, cough lead pin 6
On the other hand, a flange disk-shaped electrode header 6a is formed by press processing on the joint end surface with the semiconductor chip 1, and a flat plate-shaped soldering leg 6b is attached to the tip pulled out from the package 2.
is formed, and the lead pin 6 is bent into a hairpin shape by forming so that the masks of the soldering legs 6b are aligned on the same plane on the lower surface side of the buff cage 2. A surface mount type semiconductor VT device with such a structure is
When mounting on a printed wiring board, the soldering legs 6b in the shape of a flat plate are mounted on the board with the flat plate-shaped soldering legs 6b facing downward, and the soldering is performed by soldering reflow or the like. Next, a method for manufacturing a semiconductor device having the above structure will be explained with reference to FIG. First, an electrode pin 6a is press-molded in advance on one end of a lead pin 6 cut to an appropriate length from a nine-wire wire.
As shown in FIG. 1a), two lead pins 6 are arranged coaxially on both sides of the semiconductor chip 1 with the semiconductor chip 1 sandwiched in the center, and the semiconductor chip 1 and the electrode header 6a are joined by soldering or the like.
Next, in the same figure (as shown in BL, the semiconductor chip 1 and the lead pin 6
The assembly is inserted into a mold, and a resin package 2 is formed so as to seal the periphery of the semiconductor chip. Next, the lead pin 6 is pulled out from the pan cage 2, and both ends of the lead pin 6 are cut to a predetermined length (the cutting positions are indicated by the dashed line), and the tip of the lead pin 6 is pressed from above and below with the press 7, and this part is A flat plate-shaped soldering leg 6b as shown in the same figure (Cl) is formed.Finally, the same figure (di
Pull out the soldering legs 6b from the package so that they are flush with the lower surface of the bankage 2, or form them into a hairpin shape with the soldering pins 6 facing inward as shown in the figure. In addition, the electrode header 68 of the semiconductor chip 1 and the lead pin 6
Methods other than soldering, such as pressure welding, can also be used to connect the parts. In this case, it is preferable to seal the package 2 using, for example, glass instead of resin. Next, Fig. 5 shows a manufacturing method different from Fig. 4. In FIG. 5, first the semiconductor chip 1 and the lead pin 6 are bonded as shown in IJ1) and (b) of the same figure, and then the package 2
After sealing, the lead pins 6 protruding from both ends of the package 2 are bent approximately at right angles as shown in the figure (el), and then the tips of the lead pins 6 are pressed to form a cough part as shown in the figure 1dl. Form the soldering leg portion 6b in the shape of a flat plate.Finally, as shown in +a) of the same figure, the soldering leg portion 6b is formed.
Form the lead into a predetermined shape by bending it into a hairpin shape toward the bottom of the package 2 so that the sides b are on the same plane. Moreover, FIGS. 6 and 7 show an example in which lead pins are surface-treated in advance to improve solderability when surface-mounting a semiconductor device on a printed wiring board. That is, in FIG. 6, the surface of the lead pin 6 pulled out from the package 2 is subjected to a surface treatment before the soldering legs are press-molded on the tip of the lead pin 6. It is coated with a metal coating layer 7 made of silver or the like. Note that the wire of the lead pin 6 has copper (Cu) as its core material and nickel (Ni) on its surrounding surface.
If it is plated, metal coating layer 7 (solder)
When attaching the lead pin 6, the surface of the lead pin 6 is treated with a highly active Franks and then dipped. It shall be covered by a plating method. Note that if the thickness of the metal coating layer 7 is thin, the metal coating layer 7 may be locally peeled off due to the pressing force when the soldering legs are pressed onto the lead pin 6 in the next step, and the base metal of the lead pin 6 may be peeled off locally. Nickel (which has poor wettability with solder) is exposed, and there is a risk of soldering failure when soldering to a printed wiring board. Therefore, if the thickness of the metal coating layer 7 is at least 1 μm or more, [111] will not occur in the metal coating layer 7 even if press working is performed thereafter, and good solderability with the printed wiring board will be achieved. is obtained. In other words, a sample is prepared by applying a metal coating layer 7 of solder to the surface of the beam-doped pin 6 shown in FIG. This table shows the results of a solderability test in which the sample was immersed in a solder bath based on the solderability wiping test method and evaluated in accordance with Section 3.4 of the same standard. As is clear from this test result, if the layer thickness d of the metal coating layer (solder) previously deposited on the surface of the lead pin 6 is 1 μm or more, the solder adhesion rate of the immersed part is 9594 or more, which means that the solder is good. It has been confirmed that it provides good adhesion. Note that the layer thickness of the metal coating layer 7 depends on the surface treatment time. Considering economic efficiency such as cost, it is preferable to set the thickness to 10 μm or less. On the other hand, FIG. 7 shows the surface of the lead pin 6 after the soldering leg 6b is press-formed on the tip of the lead pin 6 (the state shown in ``C'' in FIG. 4 or 1dl in FIG. 5). An example in which a metal coating layer 7 is deposited is shown. After pressing the soldering legs 6b to the lead pins 6 in this way, the metal coating layer 7 is
By depositing the metal coating layer 7, there is no fear of the metal coating layer 7 peeling off during press working as described in FIG. 6, and the solder adhesion is further improved. Next, as applied examples of the embodiments shown in FIGS. 1 to 3, several modified examples in which the shape of the bunkage 2 is changed are shown in FIG. 9. In other words, in the figure (al), a part of the upper surface of the cylindrical puff cage 2 is made flat, so that the pan cage 2 can be stably taped and pinked up when handling semiconductor devices with an automatic mounting machine or the like. In addition, the same rI!J (bl means the same idea, with the outer shape of the puff cage 2 being prismatic (square prism. or polygonal prism). Furthermore, the same part TC) means both ends of the bottom surface of the package 2. A recess indicated by reference numeral 2a is cut out in the recess 2a, and the soldering leg 6 of the lead pin 6 is bent into the recess 2a in a hairpin shape.
The tip of b is placed flush with the bottom surface of buff cage 2, and this structure not only stabilizes the mounting posture when mounting semiconductor devices on a printed wiring board, but also prevents soldering during handling. It is possible to protect the attached leg portion 6b from being unnecessarily deformed due to external force. In addition, the same figure (dl is (
C) The recesses 2a described in the figure are formed on each side of the pan cage 2 (quadrangular prism shape). For example, the process of bending the lead pin 6 with an automatic lead bending machine (Fig. Figure (C)) provides the advantage of being able to freely select the direction of the package 2. [Effects of the Invention] Since the two-terminal surface mount semiconductor device of the present invention is constructed as described above, it achieves the following effects. (1) Press the tips of the lead pins to form flat soldering legs, align the plate surfaces of the soldering legs on the same plane, and pull out each lead pin from both ends of the package into a hairpin shape. By molding the semiconductor device into a printed wiring board, it is possible to use the same inexpensive round wire lead pins as conventional lead-type semiconductor devices without using an expensive dedicated lead frame made of custom-made crystals. It is possible to stably mount the device on the surface and perform surface mounting. (2
) Before pressing the soldering legs onto the lead pins pulled out from the package. By applying a metal coating layer with good solder adhesion to the surface in the subsequent state, good solderability can be ensured when soldering to a printed wiring board. In addition, especially when applying a metal coating layer to the lead pin before press-forming the soldering legs, the thickness of the metal coating layer should be set to 1 to 10 μm to ensure a sufficient layer thickness. , there is no risk of problems such as the metal coating layer peeling off locally during the next pressing process and the underlying metal of the lead pin being exposed, and stable solderability can be achieved. {3} In this way, it is possible to provide a two-terminal surface-mounted semiconductor device that can be stably surface-mounted on a printed cotton distribution board at a low manufacturing cost and has good solderability.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing the structure of one embodiment of the present invention;
Figure 2. Figure 3 shows the end view and bottom view of Figure 1, and Figure 4 (a).
l~+dl are the manufacturing process diagrams in Figure 1, and ta+~《e in Figure 5.
) is a manufacturing process diagram different from Figure 4, Figures 6 and 7 are perspective cross-sectional views of an example in which a metal layer with good solder adhesion is applied to the lead pin, respectively, and Figure 8 corresponds to Figure 6. Characteristic diagrams showing the solderability test results, Figures 9(a) to 9(b) are external diagrams showing different application examples of the present invention, and Figure 1
0 is a perspective structural diagram of a conventional two-terminal surface mount type semiconductor device, and FIGS. 11(a) to 11(d) are manufacturing process diagrams of the semiconductor device shown in FIG. In the figure, 1: semiconductor chip, 2: package, 6: lead bin,
6b: soldering leg, 7: metal coating layer. Figure 3 I4rl1 0 15 Figure 8 Figure 10

Claims (1)

[Claims] 1) It is an assembly of a semiconductor chip sealed in a package and lead pins pulled out coaxially from both ends of the package with the semiconductor chip sandwiched in the center, and the tips of the lead pins are pressed. is applied to form a flat soldering leg, and each lead pin pulled out from both ends of the package is formed into a hairpin shape with the plate surfaces of the soldering leg aligned on the same plane. Two-terminal surface-mount semiconductor device. 2) In the semiconductor device according to claim 1, a metal coating layer having a thickness of 1 to 10 μm and having good solder adhesion is formed on the surface of the lead pin before pressing the tip of the lead pin. A two-terminal surface-mount semiconductor device characterized by: 3) In the semiconductor device according to claim 1, after the soldering leg is pressed onto the tip of the lead pin, a metal coating layer with good solder adhesion is formed on the surface of the soldering leg. A two-terminal surface-mount semiconductor device with special features.