KR20000050864A - Low temperature cofired ceramic on metal module - Google Patents

Abstract

PURPOSE: A low temperature cofired ceramic-on-metal(LTCC-M) module coupled to a flat-plate type insulator is provided to eliminate a short problem on a side and a bottom of the LTCC-M. CONSTITUTION: A low temperature cofired ceramic-on-metal(LTCC-M) module coupled to a flat-plate type insulator comprises a metal substrate(10), a ceramic stack(20), an electrode(40), a flat-plate type insulator(50), a lead frame fixing element(55) and a clip type lead frame(60). The ceramic stack is stacked on the metal substrate. The electrode is formed at a side on the ceramic stack. The flat-plate type insulator has a portion adhered by adhesive to a position corresponding to the electrode on the bottom of the metal substrate. The lead frame fixing element is printed at a position corresponding to the electrode on the bottom of the flat-plate type insulator. The clip type lead frame is fixed by dipping after contacting the electrode and lead frame fixing element.

Description

LOW TEMPERATURE COFIRED CERAMIC ON METAL MODULE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature sintered substrate module, and in particular, a low temperature sintered substrate (Low Temperature Cofired Ceramic on Metal, hereinafter referred to as LTCC-M) that laminates ceramic on a metal substrate and simultaneously bakes at low temperature. The present invention relates to a low-temperature sintered substrate module in which a plate-type insulator is coupled to a space between a clip-type lead frame and a metal substrate to ensure operation stability and to reduce manufacturing processes and costs.

It is no exaggeration to say that electronic products using circuits tend to be commercialized and popularized by replacing complex circuits with less-volume substrates. The lead frame is used to fabricate a circuit in the form of a substrate in the form of a module that is easily removable and attached to the main device as needed. The lead frame is changed and developed in various forms according to the shape of the substrate. As semiconductor devices advance, high integration, high density, high performance, and high reliability are required. As a result, achieving low cost has become a goal of semiconductor devices, and various studies have been conducted for this purpose. In order to meet these low price requirements, LTCC-M module with clip-type lead frame was devised as a part of process reduction and low cost and easy process development. By the way, when the material of the substrate to which the lead frame is attached is an electrically insulating material, it is not a big problem, but in the case of an electrically conductive material, there is a disadvantage that may cause a short. In order to overcome this disadvantage, a low temperature sintered substrate module with a clip-type lead frame proposed in the related art will be described below.

1 is a flow chart showing a manufacturing process of a conventional low temperature sintered substrate module with a clip-type lead frame, and Figure 2 (a) to (g) is a conventional clip-type lead frame is attached according to the process shown in FIG. Figure 11 shows longitudinal sections of a low temperature sintered substrate module.

In FIG. 1, reference numeral 101 denotes a step of printing a dielectric on the bottom of a metal substrate of the LTCC-M device. The dielectric is a polymer-based material whose electrical properties are determined depending on the presence or absence of voltage. When the dielectric printing step 101 is completed, a first drying step 102 is performed to dry the printed dielectric material at a temperature of about 95 degrees for about 10 minutes. When the first drying step 102 is completed, the dielectric is subjected to a first firing step 103 which is heated at about 200 ° C. for 2 hours. When the first firing step 103 is completed, the electrode printing step 104 is performed. The electrode printing step 104 is to print an electrode at a predetermined position on the dielectric. When the electrode printing step 104 is completed, a second drying step 105 for drying for about 10 minutes at a temperature of about 95 degrees is performed. When the second drying step 105 is completed, a second firing step 106 of baking the electrode printed on the LTCC-M device is performed. The second firing step 106 is for stably coupling the LTCC-M device and the printed electrode. When the second firing step 106 is completed, a lead frame joining step 107 for joining the clip type lead frame and the electrode is performed. The clip-type lead frame used at this time has an insulating portion formed by coating a polymer-based material at a position in contact with the side of the LTCC-M device. Therefore, the insulating part is interposed between the side of the LTCC-M device and the lead frame, and the lead frame is fixed in contact with the electrodes. When the lead frame joining step 107 is completed, a dipping step 108 for fixing the connection between the electrode and the clip-type lead frame is performed. The dipping step 108 is to immerse and remove the LTCC-M device coupled to the clip-type lead frame in a tub of about 230 degrees to about 260 degrees for 3 to 5 seconds to ensure uniform connection and adhesive strength will be.

2A illustrates a longitudinal section of an LTCC-M device in which a plurality of circuits are embedded. Reference numeral 1 denotes a metal substrate of the LTCC-M device. On the metal substrate 1 is laminated a ceramic laminate 2 having multiple circuits therein. The metal substrate 1 and the ceramic laminate 2 are sealed by a koba. FIG. 2B shows a state in which a dielectric 3 that does not flow when a voltage is applied is printed on the bottom surface of the metal part 1 of the LTCC-M device. That is, the longitudinal cross-sectional view of the LTCC-M device in the dielectric printing step 101 shown in Figure 1 is completed. 2 (c) shows a state in which the printed dielectric material 3 is stable to the metal substrate 1 by high temperature heat treatment. That is, the longitudinal cross-sectional view of the LTCC-M device in the state in which the first drying step 102 and the first firing step 103 of FIG. 1 are completed is shown. 2 (d) shows a state in which an electrode 4 connected to a circuit is printed so that circuits embedded in the LTCC-M device can operate. That is, the longitudinal cross-section of the LTCC-M device after the electrode printing step 104 of FIG. 1 is completed is shown. The printed electrode 4 is applied to the LTCC-M device as shown in FIG. 2E by high temperature treatment such as the second drying step 105 and the second firing step 106 of FIG. 1. It is reliably combined. 2 (bar) shows a clip-shaped lead frame 5. The clip-shaped lead frame 5 is coated with an insulator 6 for preventing a short at a portion in contact with the side surface of the LTCC-M element. The clipped lead frame 5 is elastic and is a conductor. The lead frame joining step 107 of FIG. 1 is performed by pushing the clip-shaped lead frame 5 in the direction of the arrow shown in FIG. 2 (bar). 2 (g) shows a longitudinal section of the LTCC-M module to which the clip type lead frame is coupled after the LTCC-M element is placed in a lead bath while the clip type lead frame 5 and the electrodes are in contact with each other.

However, the LTCC-M module to which the clip type lead frame is coupled has the following problems.

First, in the dipping step, the LTCC-M device in which the clip type lead frame is coupled is immersed in a lead bath of about 230 degrees to 260 degrees, and the insulating portion of the clip type lead frame, which is the polymer material, is melted. Accordingly, a side short phenomenon occurs in which the metal substrate and the clip-type lead frame are shorted, thereby causing the LTCC-M module to malfunction.

Second, in the dipping step, the LTCC-M device in which the clip type lead frame is coupled is immersed in a lead bath of about 230 degrees to 260 degrees, so that the dielectric material of the polymer material melts. Therefore, the bottom short phenomenon of the metal substrate may occur due to the breakdown voltage, which may cause the LTCC-M module to malfunction.

Third, the conventional low temperature sintered substrate module is manufactured through a drying and firing step after the dielectric and electrode printing step, respectively. These steps are performed at high temperatures of 95 degrees and 750 degrees, respectively, which is time consuming and costly to create such a process environment. Thus, the chip manufacturing cost is significantly increased.

Fourth, a separate processing step for making an insulation part in the clip-type lead frame is required.

Fifth, in the conventional low temperature sintered substrate module, since the clip type lead frame is fixed to the metal substrate by one point, sufficient bonding strength cannot be obtained during frequent insertion and detachment.

Accordingly, the present invention has been invented to solve the above problems, the first object of the present invention is to provide a low-temperature sintered substrate module is coupled to the plate type insulator that can solve the LTCC-M side short problem.

A second object of the present invention is to provide a low temperature sintered substrate module incorporating a flat plate insulator that can solve the LTCC-M bottom shot problem.

A third object of the present invention is to provide a low temperature sintered substrate module incorporating a flat plate insulator which reduces the manufacturing process of the low temperature sintered substrate module.

A fourth object of the present invention is to provide a low temperature sintered substrate module which reduces manufacturing cost by improving the process environment of a time and costly process during the manufacturing process of a low temperature sintered substrate module.

In order to achieve the above object, according to the present invention, a low temperature sintered substrate module having a flat plate type insulator is coupled to a metal substrate; A ceramic laminate stacked on the metal substrate; An electrode formed on one side of an upper surface of the ceramic laminate; A flat plate insulator having a portion bonded to the bottom surface of the metal substrate by using an adhesive at a position corresponding to the electrode; A lead frame fixing part printed at a position corresponding to the electrode on the bottom surface of the flat plate insulator; And a clip type lead frame which is fixed by being in contact with the electrode and the lead frame fixing part. The planar insulator is bonded in a state where a predetermined length protrudes from the metal substrate. The flat plate insulator is a green sheet.

1 is a flow chart showing a manufacturing process of a conventional low temperature sintered substrate module with a clip-type lead frame,

Figure 2 (a) to (g) is a view showing the longitudinal section of the conventional low-temperature sintered substrate module with a clip-type lead frame attached to the process shown in Figure 1,

Figure 3 is a flow chart showing the manufacturing process of the low-temperature sintered substrate module coupled to the insulator according to the present invention, and

4A to 4F are longitudinal cross-sectional views of a low temperature sintered substrate module to which a flat plate insulator is coupled according to the process illustrated in FIG. 3.

<Explanation of symbols for main parts of drawing>

10: metal substrate 20: ceramic laminate

30 adhesive 40 electrode

50: flat insulator 55: lead frame fixing part

60: clip type lead frame

Hereinafter, the low-temperature sintered substrate module coupled to the insulator according to the present invention will be described in detail with reference to FIGS. 3 and 4. Figure 3 is a flow chart showing the manufacturing process of the low-temperature sintered substrate module coupled to the insulator according to the present invention, and (a) to (f) of Figure 4 is coupled to the insulator in accordance with the process shown in FIG. Figure 8 shows the longitudinal section of the low temperature sintered substrate module.

In FIG. 3, reference numeral 310 denotes an adhesive application step of applying an adhesive to the bottom of the metal substrate of the LTCC-M device. The adhesive is an inorganic adhesive. The inorganic adhesive is a material that is completely cured when heated for 30 minutes at a temperature of about 120 degrees, and does not melt even when heated at a temperature of 120 degrees or more. In the present invention, a ceramic bond was used as the inorganic adhesive. When the adhesive application step 310 is completed, an insulator attachment step 320 for attaching a flat insulator on which the lead frame fixing part is printed is applied on the applied inorganic adhesive. In the insulator attaching step 320, a portion of the flat plate insulator protrudes a predetermined length from the LTCC-M element and is temporarily fixed by the inorganic adhesive. The flat plate insulator is a material that does not melt even at a high temperature of 250 degrees or more. In the present invention, a green sheet is used as the insulator. The inorganic adhesive should be temporarily cured by drying at about 70 degrees for 30 minutes to obtain adhesive strength. Such a drying step is indicated by reference numeral 330. Next, a lead frame coupling step 340 is performed in which the lead frame fixing part printed on the flat plate insulator and the clip type lead frame are brought into contact with the electrodes of the LTCC-M device. In the frame coupling step 340, the flat plate insulator protrudes from the side surface of the LTCC-M element by a predetermined distance, and the clip type lead frame is spaced apart by the distance protruding from the LTCC-M element and the plate insulator. do. When the lead frame joining step 340 is completed, the LTCC-M device to which the clip-type lead frame is coupled is dipped in a lead bath to fix the printed electrode, the lead frame fixing part, and the clip-type lead frame at two points. The dipping step 350 is performed. Since the dipping step 350 is performed for 5 seconds at a temperature of 230 to 260 degrees, the inorganic adhesive is completely cured. In addition, since the flat sheet insulator is a green sheet, it does not melt at a temperature of 250 degrees or more, and is interposed between the LTCC-M element and the clip type lead frame according to the curing of the inorganic adhesive to prevent side and bottom shorts.

Figure 4 (a) shows the longitudinal section of the low temperature sintered substrate module with a plurality of circuits built. In FIG. 4A, reference numeral 10 denotes a metal substrate of the LTCC-M device. The ceramic laminate 20 in which the circuits of multiple stages are built is stacked on the metal substrate 10. The metal substrate 10 and the ceramic laminate 20 are sealed by a cobar. The cobar is an iron, nickel cobalt alloy used for sealing portions of metal, glass and ceramic. Figure 4 (b) shows a longitudinal section of the LTCC-M device that went through the adhesive application step 310. As shown, adhesive 30 is applied to cover a portion of the lower surface of the metal substrate 10. Although the adhesive 30 is shown as being thickly coated, this is for illustration purposes, and in actual application, the adhesive 30 is applied as thin as possible while giving an adhesive viscosity. Next, FIG. 4C shows the lead frame fixing part 55. ) Shows a planar insulator 50 in a printed state and a longitudinal section of the LTCC-M device. FIG. 4D illustrates a longitudinal cross section of the LTCC-M device that has undergone the insulator attaching step 320. As shown in the drawing, the flat plate insulator 50 is attached to the bottom surface of the metal substrate 10 in a state where the flat plate insulator 50 protrudes from a corner of the bottom surface of the metal substrate by a predetermined length. The flat plate insulator 50 is formed of a green sheet and does not melt even at a high temperature of more than 250 degrees. FIG. 4E shows the clip type lead frame 60. The clip-type lead frame 60 moves in the direction of the arrow to contact the electrode 40 of the LTCC-M element and the lead frame fixing part 55 printed on the flat plate insulator 50 and the LTCC-M element. Combined. Both ends of the clip-shaped lead frame 60 are formed to be coupled to the electrode by elasticity and are conductors. 4 (f) shows a longitudinal section of the LTCC-M device after the lead frame combining step 340 and the dipping step 350 are completed. The LTCC-M element is placed in a solder tank and dipped in a state in which the clip type lead frame 60 is temporarily fixed while being in contact with the electrode 40 and the lead frame fixing part 55. When the dipping step 350 is completed, the side of the LTCC-M device and the clip-shaped lead frame 60 are spaced apart by the length of the planar insulator 50 protruding from the metal substrate 10. And the clip-shaped lead frame 60 are insulated by a flat plate insulator fixed by the adhesive 30. The clip-type lead frame 60 is fixed to the LTCC-M element by two points by a lead frame fixing part 55 printed on the electrode 40 and the plate-type insulator 50 in the dipping step, so that the low temperature sintered substrate Form a module. That is, the low-temperature sintered substrate module to which the flat plate type insulator is coupled may include a metal substrate 10, a ceramic laminate 20 stacked on the metal substrate 10, and one side of an upper surface of the ceramic laminate 20. The formed plate 40 and the plate insulator 50 having a portion bonded to each other by using the adhesive 30 at a position corresponding to the electrode 40 on the lower surface of the metal substrate 10. A lead frame fixing part 55 printed at a position corresponding to the electrode 40 on a lower surface of the bottom surface, and a clip type lead frame fixed by being dipped in contact with the electrode 40 and the lead frame fixing part 55 60).

Therefore, the effects of the low temperature sintered substrate module according to the present invention as described above are as follows.

First, the plate type insulator may increase the adhesive strength of the clip type lead frame by printing the lead frame fixing part on the green sheet which does not melt even at a dipping temperature. This increases the reliability and durability of the LTCC-M module, ensuring stable operation even when the LTCC-M module is frequently inserted and removed from the socket of the main circuit.

Second, since the plate insulator is adhered to the lower surface of the metal substrate so that the metal substrate and the clip-shaped lead frame are separated by a predetermined distance, the side short between the metal substrate and the clip-type lead frame may be prevented.

Third, from the dielectric coating step to the second firing step in the LTCC-M module fabrication processes in which the conventional clip type lead frame is coupled by dipping in a state where the flat plate insulator and the clip type lead frame assembled by the adhesive are bonded to each other. Steps can be reduced.

Fourth, the manufacturing cost can be reduced by improving the process environment by reducing the time and costly drying and firing step of the LTCC-M module manufacturing process combined with the conventional clip-type lead frame.

As mentioned above, although this invention was demonstrated concretely by the above-mentioned Example, this invention is not limited to this, The deformation | transformation and improvement are possible within the range of common knowledge of a person skilled in the art.

Claims (4)

Metal substrates; A ceramic laminate stacked on the metal substrate; An electrode formed on one side of an upper surface of the ceramic laminate; A flat plate insulator having a portion bonded to the bottom surface of the metal substrate by using an adhesive at a position corresponding to the electrode; A lead frame fixing part printed at a position corresponding to the electrode on the bottom surface of the flat plate insulator; The low temperature sintered substrate module coupled to the flat plate insulator, characterized in that consisting of a clip-type lead frame is fixed by being in contact with the electrode and the lead frame fixing portion. The low temperature sintered substrate module according to claim 1, wherein the flat plate insulator is a green sheet. The low temperature sintered substrate module as claimed in claim 1, wherein the flat plate insulator is bonded in a state of protruding from the metal substrate by a predetermined length. 2. The low temperature sintered substrate module as claimed in claim 1, wherein the clip type lead frame is advantageously fixed to the electrode and the lead frame fixing part by dipping.