SUBMINIATURE SURFACE MOUNT DEVICE FUSE

Technical Field

[1] The present invention relates to a fuse, and more particularly, to a subminiature surface mount device fuse. Background Art

[2] In general, a fuse is fused by heat when electric current of more than fixed amount flows inside an electric circuit, thereby keeping safety. The fuse is generally made of alloy of lead, tin, antinium and so on, and made of aluminum or tungsten wires for small electric current.

[3] An SMD (Surface Mount Device) fuse is mounted on a Printed Circuit Board

(PCB) to prevent a damage of a circuit due to an excessive current. Such an SMD fuse must be designed to cut off surge current in a very short period time.

[4] FlG. 1 is a view showing a structure of a conventional SMD fuse.

[5] As shown in FlG. 1, the SMD fuse includes a fusible body 14 fused when electric current of more than rated current flows, a ceramic housing 11 for electrically cutting off the fusible body 14 from the external electronic components, and a cap 12 for sealing both ends of the ceramic housing 11 and connecting the fusible body 11 with an electric circuit. The fusible body 14 is fixed at both ends of the ceramic housing 11 by soldering.

[6] However, such SMD use shown in FlG. 1 is too short, and so the fusible body 14 is not located at the center of the inside of the ceramic housing 11 but adhered on the inner wall surface of the ceramic housing 11. At this time, the fusible boy 14 is not fused within a standard time period since it is deprived of its resistance heat to the ceramic housing 11 when excessive current is applied. So, the fusible body 14 cannot perform its role as a fuse since it is not fused within the standard time period. Disclosure of Invention Technical Problem

[7] Accordingly, it is an object of the present invention to provide a subminiature SMD

(Surface Mount Device) fuse, in which a fusible body is located at the center of the inside of a ceramic housing.

Technical Solution

[8] To achieve the above object, the present invention provides a subminiature SMD fuse including a ceramic housing having a central hole formed therein in such a fashion as to perforate therethrough; center guides fit on both ends of the ceramic housing; a fusible body fixed at both ends thereof by the center guides and located inside the

ceramic housing; a solder for fixing both ends of the fusible body at the both ends of the ceramic housing; and caps for hermetically sealing the both ends of the ceramic housing. The center guide includes a body having a hole formed at the center thereof, and a guide protruding from the hole of the body toward the inside of the ceramic housing. The body of the center guide abuts against the end surface of the ceramic housing and has the same size as the end surface of the ceramic housing. The guide of the center guide is bent from the body at a predetermined angle, and abuts against the inner wall surface of the ceramic housing.

Advantageous Effects

[9] The subminiature SMD fuse according to the present invention can completely solve a problem of a pre-arcing time current characteristic in that a fusible time period is extended or remaining resistance occurs since the fusible body abuts against the inner wall of the ceramic housing. Brief Description of the Drawings

[10] FlG. 1 is a view showing a structure of a conventional surface mount device fuse.

[11] FlG. 2 is a view showing a structure of a subminiature SMD (Surface Mount

Device) fuse according to a preferred embodiment of the present invention.

[12] FIGS. 3 and 4 are detailed views of a center guide of FlG. 2

[13] * Explanation on essential reference numerals in drawings *

[14] 21: ceramic housing

[15] 22: center guide

[16] 23: fusible body

[17] 24: soldering

[18] 25: cap

Mode for the Invention

[19] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[20] A subminiature SMD (Surface Mount Device) fuse according to a preferred embodiment of the present invention is manufactured in a process of fitting center guides on both ends of a ceramic housing, putting a fusible body into the ceramic housing and soldering them, assembling caps to the both ends of the ceramic housing, whereby the fusible body can be located at the center of the inside of the ceramic housing by the center guides.

[21] FIG. 2 is a view showing a structure of the subminiature SMD fuse according to the preferred embodiment of the present invention.

[22] Referring to FIG. 2, the subminiature SMD fuse includes the ceramic housing 21 having a central hole 21a formed therein in such a fashion as to perforate therethrough,

the center guides 22 fit on the both ends of the ceramic housing 21, the fusible body 23 fixed at both ends thereof by the center guides 22 and located at the inside of the ceramic housing 21, a solder 24 for fixing both ends of the fusible body 23 at the both ends of the ceramic housing 21, and caps 25 for hermetically sealing the both ends of the ceramic housing 21. [23] FlG. 3 is a sectional view of the center guide of FlG. 2, and FlG. 4 is a perspective view of the center guide of FlG. 2. [24] Referring to FIGS. 3 and 4, the center guide 22 includes a body 22a having a hole

22b formed at the center thereof, and a guide 22c protruding from the hole 22b of the body 22a. [25] Here, the body 22a of the center guide 22 has the same area as that of the end of the ceramic housing 21, and the hole 22b formed at the center of the body 22a also has the same size as the central hole of the ceramic housing 21. [26] Furthermore, the guide 22c of the center guide 22 protrudes from the hole 22b of the body 22a toward the inner wall surface of the ceramic housing 21. Particularly, the guide 22c is bent at a predetermined angle (α) in a direction of the body 22a, and at this time, the angle is about 30°~80°. [27] Therefore, the lower portion of the guide 22c connected to the body 22a is smaller than the upper portion of the guide 22c, and the upper portion of the guide 22c has the same size as the central hole 21a of the ceramic housing 21. [28] As described above, in the subminiature SMD fuse according to the present invention, the fusible body 23 can be located at the center of the ceramic housing 21 without abutting against the inner wall surface of the ceramic housing 21 since the center guides 22 are fit on the both ends of the ceramic housing 21. [29] Referring to FlG. 2, a manufacturing method of the subminiature SMD fuse according to the present invention will be described as follows. [30] First, the central hole 21a which is empty for positioning the fusible body 23 is formed at the center of the housing made of a ceramic material of high purity, namely, the ceramic housing 21. [31] At this time, the ceramic housing 21 is in the form of a cube, and the central hole

21a is formed at the center of the ceramic housing 21 and has a predetermined diameter. Therefore, the central hole 21a is in the form of a round. [32] Next, the center guides 22 are fit on the both ends of the ceramic housing 21.

[33] At this time, the center guides 22 are to locate the fusible body 23 at the center of the ceramic housing without abutting against the inner wall of the ceramic housing 21, and made of brass plated with silver. [34] After that, the fusible body 23 is inserted into the central hole 21a of the ceramic housing 21, and then, a solder 24 is applied to the both ends of the ceramic housing 21.

[35] Here, the fusible body 23 is located inside the ceramic housing 21 without abutting against the inner wall of the ceramic housing 21 by the medium of the center guides 22 at the ends of the ceramic housing 21.

[36] Finally, the caps 25 are assembled to the both ends of the ceramic housing 21.

[37] Here, the cap 25 is made of a conductive metal material.

[38] While the present invention has been described with reference to the particular il¬ lustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.