JPS63296258A - Mounting structure of electronic component - Google Patents

Abstract

PURPOSE:To obtain structure good in a heat-dissipation effect, by providing both facing sides of tabs with a plurality of tab link leads respectively and next by drawing the tab link leads partially outside from a resin sealed matter and connecting them to a conductor layer of a wiring substrate. CONSTITUTION:Both facing sides 11a, 11b of a tab 11 of a lead frame made of a copper plate are provided connectedly with a plurality of tab leads 12, 13 so that heat transfer (heat-dissipation) effect can be upgraded. A circuit element 10 is fixed on the tab 11, and electrodes of the element are connected 15 to their corresponding leads 12, and resin 16 is used to seal the element. The leads 13 are detached to be separated from an outer frame. Since this composition allow a plurality of tab lead 12' s end parts to be exposed outside to the sealed matter 16, a heat-dissipation effect is improved. Accordingly heat generated from the circuit element can be radiated from a plurality of the tab link leads on both its sides.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mounting structure on a wiring board in the field of semiconductor technology, particularly in the field of electronics such as consumer ICs and linear circuits.

[Prior Art] Plastic packages, especially resin mold packages using epoxy resin as a sealing material, are commonly used as packages for consumer ICs, linear ICs, and other small signal ICs due to their low manufacturing costs. ing.

As a structure for improving the heat dissipation effect in such a resin mold package, a structure as disclosed in Japanese Patent Laid-Open No. 51-45977 is known.

Incidentally, due to the demand for miniaturization of devices into which electronic components are installed, efforts are being made to miniaturize electronic components, especially their packages.

[Problems to be solved by the invention] Conventionally, high-density packaging has progressed even in linear ICs, and there has been a demand for smaller package outlines.
As small-signal ICs such as C and other small-signal ICs are becoming more highly integrated, the number of circuit elements that generate a large amount of heat is increasing, and even small-signal ICs must be given sufficient consideration to the heat dissipation effect. It is extremely difficult to miniaturize the structure disclosed in .

Therefore, the purpose of the present invention is to
The object of the present invention is to provide a mounting structure for electronic components such as those that are low cost, small, and have good thermal characteristics.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a tab having sides opposite to each other, one end side being close to the side of the tab,
A circuit element having a plurality of leads extending in a predetermined direction from an end side to be connected to a wiring board, and a plurality of electrodes fixed on the tab, and an electrode of the circuit element and one end side of the lead. A mounting structure for a semiconductor device comprising a wire connecting the leads, and a resin sealing body that seals the circuit element, the tab, the wire, and one end side of the lead so as to expose the other end side of the lead, A plurality of tab connecting leads are connected to each of the tabs in the semiconductor device on one side and the opposing side, and a portion of the tab connecting leads are extended out of the resin sealing body and connected to the leads. The electronic component mounting structure is characterized in that the electronic component is connected to the conductor layer of the wiring board.

Embodiment] FIG. 1 shows a resin mold type lead frame according to an embodiment of the present invention. Pure copper with good thermal conductivity α (α = 0, 92 ca
The lead frame is made by patterning a copper-based metal thin plate (1/cm/cm"/5ec) by precision pressing or etching. In addition, in order to improve mechanical strength and thermal conductivity, a relatively thick copper plate is used. , for example 0.2
A lead frame made from a 5mm thick copper plate is used.

As shown in FIG. 1, this lead frame increases the heat transfer (heat radiation) effect by increasing the number of tab leads 12. That is, mutually opposing sides (l l
Tab with a, 1 lb)! 1, it has a plurality of tab leads 12 connected to each of one side (lla) and the opposite side (11b). It extends in the same direction as the lead 13 and has approximately the same width as the lead 13. For this reason, when bending the leads, the load is applied evenly to facilitate bending, and the tips of the leads are also aligned uniformly.

Next, a semiconductor using the lead frame shown in Figure 1 (
rG) assembly will be explained.

As shown in FIG. 2, after fixing the circuit element 10 on the tab 11, each electrode of this circuit element 10 and the tip of the corresponding lead 13 are connected with a thin wire 15, and then The inside is molded with resin and molded part (sealing body)
At 16, the tab lead and the parts other than the outer ends of the lead are covered, and the tab lead 12 is cut and separated from the outer frame.

According to the electronic component obtained in this way, the package can be made small. Further, since the outer ends of the plurality of tab leads 12 protrude outward from the sealing body 16, they function like heat radiation fins, and the heat radiation effect can be increased. In addition, heat generated from circuit elements can be removed from both sides of the tab (opposite sides of the tab).
The idea is to disperse the heat from a plurality of tab-connected leads provided in the heat exchanger, which has the effect of quickly and evenly dispersing the heat. Furthermore, since the tab lead 12 is made of copper, which has good thermal conductivity, it has excellent heat dissipation.

The mounting structure (electronic component module) of the present invention is shown in FIG.

That is, the figure shows the state when the ICl 3 is attached to the ceramic substrate 20, and the outer ends of the leads 13 are connected to the wiring layer (not shown) of the ceramic substrate (wiring board) 20 via solder (not shown). Fixed. In addition, since the ceramic substrate 20 has high thermal conductivity, the tab lead 12
The outer end of the lead is bent downward together with other leads and fixed to the ceramic substrate 20 via solder (not shown).

Further, as shown in FIG. 4, the tips of the leads 13 and tab leads 12 can be directly connected to the ceramic substrate 17 without bending them.
If a structure is adopted in which the parts are fixed with solder 23 in contact with the parts, the mounting area becomes narrower. Furthermore, by making the distance (Q) from the outer edge of the mold part 16 to the bending part of the lead 13 and tab lead 12 as short as possible, and by lowering the height H) of the lead 13 and tab lead 12, the cable path can be shortened. Furthermore, heat dissipation characteristics are improved.

[Effect] In this way, the outer end of the tab lead 12 that supports the circuit element that becomes the heat source is connected to the ceramic substrate 20 that serves as a heat sink with high thermal conductivity, so that heat is transferred to the tab lead 12.
Heat is radiated sequentially from the heat sink through the heat sink. In addition, since the tab lead length and path are short, the heat transfer path is also short and the heat dissipation effect is high. The mounting structure, that is, this embodiment in which the tab lead 2 is fixed to the ceramic plate, has a much lower thermal resistance than the case where the tab lead does not contact the ceramic plate (
(See Figure 5). In other words, the thermal resistance of a single package is, for example, 216, partly because the mold part has become smaller.
℃/W, but when attached to a mounting board with good thermal conductivity such as a ceramic substrate, a small package has a smaller thermal resistance than a large package.

Therefore, if the present example is used, the heat dissipation characteristics will be good even if the package (mold part) is downsized to 10 mm or less, so it is possible to downsize consumer ICs and linear ICs that generate relatively heat. It becomes possible. Furthermore, since the lead frame uses an inexpensive copper-based material, the IC is also inexpensive.

In particular, according to the present invention, since the plurality of tab leads for heat dissipation have approximately the same width as the other leads, the leads can be bent uniformly and the lead tips can be aligned. Therefore, there is no defect in soldering to the wiring board during mounting.

As described above, according to the present invention, a plurality of tab leads that are made of a metal with good thermal conductivity and extend from a tab to which a circuit element serving as a heat generation source is attached are drawn out of the sealed body and used as a heat radiator. Further, since this tab lead is connected to a heat sink (wiring board) such as an alumina ceramic substrate having good thermal conductivity, even a resin mold type IC that generates a large amount of heat can be made smaller. Also,
Since the lead frame can be made of inexpensive copper, manufacturing costs can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a lead frame according to an embodiment of the present invention, FIG. 2 is a plan view showing assembly of an IC using the lead frame of FIG. 1, and FIG. 3 is a plan view showing the mounting structure of the present invention, namely FIG. 4 is a partially sectional front view showing another implementation structure of the electronic component; FIG. 5 is a duram diagram showing the thermal resistance characteristics of the electronic component according to the present invention. IO...Circuit element, 11...Tab, 12...Tab lead, 13...Lead, 15...Wire, 16...
...Mold part, 17...Wiring board, 18...IC,
20...Ceramic board 223...Solder. Figure 1 Figure 2 Figure 4! 82 ac)

Claims (1)

[Scope of Claims] 1. A tab having sides facing each other, and a plurality of leads each having one end close to the side of the tab and the other end to be connected to a wiring board extending in a predetermined direction; a circuit element having a plurality of electrodes fixed on the tab; a wire connecting the electrode of the circuit element to one end of the lead; the circuit element, the tab, A mounting structure for a semiconductor device comprising a wire and a resin encapsulant formed by sealing one end side of a lead, wherein the tab in the semiconductor device has a plurality of tabs on each of one side and the opposite side. A mounting structure for an electronic component, characterized in that connection leads are connected, a portion of the tab connection leads are extended out of the resin sealing body, and connected together with the leads to a conductor layer of a wiring board.