JP2000183475A - Metal core substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate releasing of a conductor pad from an insulating layer without bringing about a thermal damage of an electronic component by forming a gap at exposed metal core of a bottom of a groove, casting a fusible metal or the like in the groove, and connecting the gap. SOLUTION: A sectional view shows the state that fusible metal such as solder, lead, tin or the like is melted and cast in a groove 10. The fusible metal 11 is heated to a high temperature, melted, cast in the groove 10 to thermally connect the gap provided on a metal core 3. Again, the metal 11 is heated, melted, and the liquid-like fusible metal 11 is sucked to shut off the thermal connection of the core 3. Thus, in the case of mounting an electronic component 8 on a metal core board 4, transfer of the heat is prevented, absorption of the heat can be suppressed, and the component 8 and a conductive pad 5 can be mounted without adding excess thermal stress thereto. The gap of the core 3 is connected with the metal 11 to eliminate radiating deterioration by the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal core substrate on which electronic circuits and electronic components are mounted.

[0002]

2. Description of the Related Art A metal core substrate is a substrate formed by inserting a metal layer into a part of an inner layer of a normal printed wiring board. Heat emitted from electronic circuits and electronic components mounted on the substrate is inserted into the metal core substrate. Conduction to the metal layer improves heat dissipation characteristics.

[0003] The mounting structure of a conventional metal core substrate will be described with reference to the drawings. FIG. 5 is an example showing a mounting structure of a conventional metal core substrate, and is a cross-sectional view when an electronic component is mounted on a metal core substrate formed of four wiring layers and one metal core layer for heat radiation. In the figure, 1 is an insulating layer, 2 is a wiring layer formed of an electrically conductive material such as copper, and 3 is a metal core formed of a heat conductive material such as copper or aluminum. 4 are configured.

Reference numeral 5 denotes a conductive pad, which is a metal core substrate 4
Is connected to the wiring layer 2 formed on the surface or inside. 6 is an electronic component body, 7 is a lead, and a lead 7
Is a conductive wire for extracting an electric signal from an electronic circuit formed inside the electronic component body 6. An electronic component 8 is constituted by components indicated by reference numerals 6 to 7. Reference numeral 9 denotes a joining material, which is a fusible metal such as solder, and is a material for electrically and mechanically joining and fixing the lead 7 and the conductive pad 5.

When such a mounting structure of the metal core substrate is adopted, the heat generated in the electronic component body 6 is transferred to the insulating layer 1,
Conduction is conducted to the metal core 3 via the wiring layer 2. The metal core 3 generally spreads over the entire substrate, and radiates heat to the outside by this surface area.

In this example, the case where the metal core substrate 4 is composed of four wiring layers is described. However, even if the metal core substrate has a higher multilayer wiring layer, the mounting structure of electronic components and the heat radiation structure are not limited. There is no difference.

[0007]

As described above, the mounting structure of the conventional metal core substrate is effective for absorbing and transmitting the heat discharged from the electronic component 8. But,
In the step of joining the electronic component 8 to the metal core substrate 4, a joining material 9 such as solder is thermally melted to the lead 7 and the conductive pad 5. At this time, the metal core 3 absorbs heat exhausted from the electronic component body 6, Bonding material 9 as well as propagating
Will also be absorbed and propagated. Therefore, in order to melt the bonding material 9, it is necessary to continuously apply heat to the conductive pad 5, the lead 7, and the bonding material 9 for a long time, and thus the electronic component 8 and the conductive pad 5 may be subjected to thermal stress. Too much heat stress causes electronic components 8
Causes thermal destruction, and the conductor pad is peeled off from the insulating layer 1 and cannot be joined again.

[0008] Even when the components mounted on the metal core substrate are removed by repair or the like, the bonding material 9 must be melted, so that the same thermal stress as in the mounting may be applied too much.

The present invention provides a metal core substrate that makes it difficult to apply thermal stress to components and conductive pads in a process of attaching and detaching components to and from a metal core substrate, and that absorbs and propagates heat generated from components in a normal use state. It is intended to do so.

[0010]

In the metal core substrate according to the first invention, a groove is formed from the surface of the substrate until the metal core is exposed, and a gap is formed in the exposed metal core at the bottom of the groove. The work is performed in a state where the gaps are open, and after the work, a fusible metal or the like is poured in so that the gaps are thermally connected.

Further, in the metal core substrate according to the second invention, a thermally conductive liquid is injected into the groove until the metal core is exposed from the substrate surface according to the first invention, and the groove is covered so that the liquid does not jet to the surface. Cover.

Further, a metal core substrate according to a third aspect of the present invention is one in which a heat conductive structural material is attached to a groove until the metal core is exposed from the substrate surface according to the first aspect of the present invention.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a cross-sectional view showing Embodiment 1 of the present invention.
Is the same as or equivalent to that shown in the conventional example. 10 is a groove for providing a gap in the metal core,
A groove is cut from the surface of the substrate to the lower surface of the metal core 3.

The electronic component 8 is electrically and mechanically joined to the metal core substrate 4 with the groove 10 cut. In this state, the gap provided in the metal core 3 is not thermally connected.

FIG. 2 is a sectional view showing a state in which a fusible metal such as solder, lead, tin or the like is melted and poured into the groove 10 shown in FIG. Numeral 11 denotes a fusible metal, which is heated to a high temperature and melted and liquefied, and flows into the groove to thermally connect the gap provided in the metal core 3. Heat is applied to the fusible metal 11 again to melt it, and a liquid fusible metal is sucked out, whereby the thermal connection of the metal core 3 can be cut off.

Embodiment 2 FIG. 3 is a sectional view showing a second embodiment of the present invention, wherein 1 to 10 are the same as those shown in the first embodiment. Reference numeral 12 denotes a heat conductive liquid such as mercury or florinate, which is poured until the metal core 3 is entirely covered in the groove 10. The gap provided in the metal core 3 while being poured into the heat conductive liquid 12 is thermally connected. Reference numeral 13 denotes a cover made of an elastic material such as rubber which covers the entire groove 10. The cover 13 is inserted into the groove 10 and has a packing shape that can be attached and detached, and has a structure in which the thermally conductive liquid 12 injected into the groove 10 can be easily discharged. The metal core 3 is discharged by discharging the heat conductive liquid.
Is disconnected.

Embodiment 3 FIG. 4 is a sectional view showing a third embodiment of the present invention, wherein 1 to 10 are the same as those shown in the first embodiment. Reference numeral 14 denotes a heat conductive structure material such as silicon rubber, which fills the entire groove 10. The heat conductive material 14 has a structure that can be attached to and detached from the groove 10. The gap provided in the metal core 3 is thermally connected when attached to the groove 10. Will be shut off.

[0018]

According to the first aspect of the present invention, when electronic components are mounted on the metal core substrate, a gap is formed in the metal core that absorbs heat, thereby preventing heat conduction and suppressing heat absorption. Electronic components and conductive pads can be mounted without applying extra thermal stress. In addition, by thermally connecting the gap of the metal core with a fusible metal, deterioration of the heat radiation characteristics due to the gap does not occur in a normal use state.

According to the second aspect, the thermal connection state of the gap of the metal core can be changed by injecting and discharging the thermally conductive liquid. Therefore, when the electronic component is mounted, the thermally conductive liquid is discharged and the metal core is discharged to the metal core. Heat absorption can be suppressed, and mounting can be performed without applying extra thermal stress to electronic components and conductive pads. Also, by thermally connecting the gap of the metal core with a thermally conductive liquid, in normal use conditions,
There is no deterioration in heat radiation characteristics due to the gap.

According to the third aspect of the invention, the thermal connection state of the gap of the metal core can be changed by attaching and detaching the heat conductive structural material. Heat can be suppressed, and electronic components and conductive pads can be mounted without applying extra thermal stress. In addition, by thermally connecting the gap of the metal core with the heat conductive structural material, in a normal use state, deterioration of the heat radiation characteristic due to the gap does not occur.

[Brief description of the drawings]

FIG. 1 is a diagram showing Embodiment 1 of a mounting structure of a metal core substrate according to the present invention.

FIG. 2 is a diagram showing Embodiment 1 of a mounting structure of a metal core substrate according to the present invention.

FIG. 3 is a diagram showing Embodiment 2 of a mounting structure of a metal core substrate according to the present invention.

FIG. 4 is a diagram showing Embodiment 3 of a mounting structure of a metal core substrate according to the present invention.

FIG. 5 is a view showing an embodiment of a mounting structure of a conventional metal core substrate.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 insulating layer, 2 wiring layer, 3 metal core, 4 metal core substrate, 5 conductor pad, 6 electronic component body,
Leads, 8 electronic components, 9 joining materials, 10 grooves, 11
Fusible metal, 12 cover, 13 thermally conductive liquid, 14
Thermally conductive structure.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E315 AA05 AA10 AA13 BB01 DD19 DD25 DD29 GG22 5E338 AA03 AA16 AA18 BB02 BB19 BB22 BB71 BB75 CC01 EE02 EE32 EE51 5E346 AA03 AA60 BB01 BB16 H

Claims (3)

[Claims] 1. A metal core substrate, wherein a gap portion for suppressing heat conduction is provided in a core of the metal core substrate, and a groove for storing a heat conductive material is formed in the gap portion. 2. The metal core substrate according to claim 1, wherein a cover is provided in the groove. 3. The metal core substrate according to claim 1, wherein a heat conductive structural material is attached to said groove.