Metal working – Method of mechanical manufacture – Electrical device making
Patent
1996-10-22
1998-07-28
Vo, Peter
Metal working
Method of mechanical manufacture
Electrical device making
29834, 29DIG12, 22818021, H05K 332, H05K 318, H05K 1304
Patent
active
057847797
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
PRIOR ART
The invention concerns a method for joining an electrical connection of a non-packaged IC component with a conductive strip on a substrate. In the WO 94/05139, a method for producing finely structured electrically conductive layers on a substrate is described, where a thin activation layer (forming of crystal nuclei) with the desired layer structure is applied to improve the fineness of the structure and contour sharpness, and where a thicker conductive layer made of electrically conductive metal, for example copper (Cu) or nickel (Ni), is then added to the nucleation. This layer is added through precipitation from a galvanized bath or without current from a reduction bath.
With standard joining techniques for mounting an IC component on a substrate, conductive strips are placed on the side of the substrate that faces away from the IC component and are provided with contact surfaces. Throughbores in the substrate and conductive strips are provided to join the IC component to the conductive strip contact surfaces. The IC components are positioned with their connecting surfaces over the throughbores. Thus, each connecting surface covers the associated throughbore. The contact and connecting surfaces are subsequently strengthened chemically with a metal until the metal layers in the throughbore grow together and the electrical connection is formed. The disadvantage of this joining technique is that only thin substrates can be used at moderate temperature stresses. Placing the throughbores in the substrate material is mechanically extravagant and costly. Frequently only certain types of substrate material can be used.
SUMMARY AND ADVANTAGES OF THE INVENTION
The above mentioned disadvantages of the know methods generally are overcome according to the present invention by a method for conductively joining an electrical connection of a non-packaged IC component with a conductive strip on a substrate, with an easy to metallize layer preferably being applied to the surface to be connected of the IC component, wherein a spacing means is applied to the conductive strip outside of a contact surface thereof, the surface to be connected of the IC component and the conductive strip of the substrate are positioned facing each other at a distance, and an electrically conductive material, which fills in the free volume between the two surfaces to be connected is applied simultaneously to the contact surface of the conductive strip and the surface to be connected of the IC component by the precipitation of the electrically conductive material from a galvanized bath or from a reduction bath without current.
The method according to the invention has the advantage that no throughbores are needed in the tight arrangement for the IC connections in the substrate. Thus, the thickness of the substrate material that can be used is not limited. It is possible to have substrates with structures on one side only. Thin substrates or foil substrates do not suffer a weakening of the substrate work piece. The method permits the use of all not encased integrated circuits (IC's), while other flip-chip techniques are for the most part limited to specially pretreated (bumped) IC's. It is possible to realize very short conductive connections with good thermal conductivity and improved high frequency qualities of substrates that are joined in accordance with the invention and the associated components. A damaging of sensitive components through heating during the soldering process is eliminated, and plastic parts can be arranged closer to the substrate. An automation of the method is possible. By reducing the distance between side-by-side arranged connections of the IC component as compared to packaged components, it is possible to save substrate material and material for the conductive strip and the insulating layers with a comparable use range of the circuit.
Further improvements and advantages are achieved with the additionally disclosed measures, as compared to the Prior Art. Contact connections ac
REFERENCES:
patent: 5084961 (1992-02-01), Yoshikawa
patent: 5203075 (1993-04-01), Angulas et al.
patent: 5245750 (1993-09-01), Crumly et al.
patent: 5386624 (1995-02-01), George et al.
patent: 5421081 (1995-06-01), Sakaguchi et al.
Gruenwald Werner
Haug Ralf
Hauschild Frank-Dieter
Seyffert Martin
Robert & Bosch GmbH
Vo Peter
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