DE2330161A1 - IMPROVED CIRCUITS AND METHOD OF MANUFACTURING THEREOF - Google Patents

Description

IMPROVED OCHING CIRCUITS AND AND METHOD FOR MANUFACTURING THEIR The present invention relates to printed circuit boards and, more particularly, to methods for connecting electrical and printed circuits.

5 are various conventional methods of connecting semiconductor circuits available with printed circuits.

This method usually uses high level conductive ones humps that are either on deci Talconductor element or on the printed circuit board are arranged, or protruding cable ends, deformable solder balls or conductive, non-deformable beads.

These procedures have certain drawbacks. for example, you can Short circuits between adjacent conductor tracks of the printed circuits or occur on the semiconductor element itself when considering the technique of the process not exactly under control.

Furthermore, an undesirable flow of solder back along the conductor tracks take place out of the connection zone. continue to ensure these procedures not in and of itself a spacing between the tialbleiterelement and the printed circuit. In particular, the methods are according to the prior art generally very expensive and require several processing steps.

The present invention provides methods and circuits to Semiconductor elements to be connected to other circuits. The procedure ensures an accurate Distance between the semiconductor element and the printed circuit and eliminated the undesired short circuits between closely spaced conductor tracks on the element and the printed circuit. Furthermore, no solder return flow occurs along the They burn out from the connection zones.

The processes according to the present invention require fewer process steps and less control than the prior art methods. The application of the novel processes allow unmodified semiconductor devices (i.e. such without protruding humps) to be connected quickly and safely to printed circuits in such a way that without having to fear short circuits or damage.

The subject matter of the present invention includes the method of attachment a semiconductor chip on a printed circuit, the following steps: (a) on provides a dielectric substrate with one bonded to a surface thin conductive layer before; (b) One sees a predetermined pattern of a plurality of holes in the dielectric substrate extending through the substrate extend and communicate with the underside of the conductive layer; (c) Now forms conductive pillars in the openings, which electrically connect to the underside the conductive layer and some of which are connected to the Verbino.un with further electrical circuits to the opposite lowing surface freely lies; (d) Now the lei-i, end layer transforms into a predetermined pattern of conductive material Pads around, with each conductive pad in electrical communication with a separate head Pillar stands; (e) One connects the Contact surfaces of a semiconductor element with the exposed parts of the conductive ones Acids.

The invention also provides a continuous strip with printed Circuits, each of which accommodates a semiconductor element on one side can, with lines to other electrical circuits on the opposite one Surface are provided. Each printed circuit board has (a) a thin flexible one dielectric substrate ranging in thickness from about 0.025 to 0.25 mm; (b) a predetermined pattern of conductive pads that meet a surface of the dielectric substrate are firmly bonded and have a thickness of less than about 0.17 mm; (c) a plurality of conductive pillars extending through the substrate extend therethrough and one end of which is in electrical communication with a single conductive bearing surface on one surface of the dielectric substrate and the other band thereof on the opposite surface of the dielectric substrate exposed; the exposed end of the conductive pillars forming a place which can hold a conductor element in conductive connection.

The invention will now be described in more detail with reference to the accompanying drawings Drawings in which like numerals indicate like elements: Figure 1 is a perspective view of a continuous strip of printed circuit boards; Sig. 2 is a sectional view of the strip with printed circuit boards of FIG. 1; Figures 3, 4 and 5 show sequential steps in implementation the Invention; Figure 6 shows another form in which the invention can be carried out can; Fig. 7 shows another type of printed circuit which is in implementation of the present invention are useful.

The thirty. . 1 shows a continuous strip 1o of material such as it is used for printed circuit boards, with a repeating conductive Support surfaces 14 which are fastened to a surface of the substrate 12. the Conductive bearing surfaces 14 rest from one another, are spaced and have inner ends 16, which converge to form a common surface part of the substrate. Properly shown Pillars 20 extend through substrate 12 and are in electrical communication with the conductive bearing surfaces 4 on a surface of the substrate.

The parts 21 of the conductive pillars 20 are exposed on the upper surface of the substrate and form places that later become an electrically conductive element To get in touch.

For example, an semiconductor element can be placed on the substrate bring and then electrically connect to the 'i' parts 21 via thin wires; Farther it is possible to place a semiconductor element aligned over the body 21 and to be connected to these using the flip-chip bonding method.

Fig. 2 shows a sectional view through the printed circuit of Fig. 1 along section line 2-2. Typically the dielectric substrate 12 a thickness of 2.5 to 250 micrometers. Preferably used dielectric Substrates consist of thin flexible polyimide, polyester, acrylic resin, fluorocarbon, Polysulfone, polyamide, polyolefin and silicone films and made of glass fiber reinforced thermoplastics.

The conductive bearing surfaces 14 are preferably metallic and consist, for example, of aluminum, iuf er, winding, silver, gold and similar alloys these metals - with each other or with other metals such as iron or obalt - are also very useful. Likewise, bimetal strips - e.g. made of solder-coated Aluminum or gold-plated nickel - proved to be useful. The thickness of the guide Support surfaces must be sufficient to allow electrical conduction, and can to about 125 micrometers, although for economic reasons one Thickness of 25 micrometers is generally preferred.

The conductive pillars 20 typically have a diameter of Range from 100 to 250 microns. The length with which the Yeil 21 crosses the surface protruding from the substrate 12 is generally in the range of 0 to 250 micrometers.

The conductive pillars 20 are preferably made of metals such as tin / bei-solder, Gold, nickel, copper and their combinations, although other conductive materials as well such as aluminum, silver, indium and tin can be used.

The printed circuit 10 can be made by various methods produce. Preferably, one first forms one in a dielectric substrate A plurality of cookers in a predetermined pattern, being on a surface a continuous conductive layer is firmly applied to the substrate. The 1ig. 3 shows, under the reference number 30, a preliminary stage of such a circuit board from one dielectric substrate 12 having a coated on one surface thereof continuous conductive layer 13. The substrate 12 is already provided with holes 15, which extend to the underside of the conductive layer 13 therethrough.

The holes 15 can be provided in accordance with conventional procedures - e.g. by chemical processing (e.g. according to US-PS 3,395,057), laser, electron beam or mechanical drilling, grinding or the like.

Then the holes 15 - verb Fig. 4 - with the conductive columns 20 provided. The conductive pillars 20 lie on the underside of the conductive layer 13 and are electrically connected to it, while parts 21 of the conductive Pillars 20 remain open; here they will be discussed later with more circuit elements - For example, conductor or other structural elements connected. The conductive layer 13 is then according to conventional procedures (e.g. covering with @hotolack and Etching) to a predetermined pattern of conductive support surfaces 14 (see Fig. 1 and 2) converted. The predetermined pattern of the conductive pads must be so be designed so that the converging ends 16 of the conductive support surfaces 14 are in electrical communication with one end of the conductive pillars 20.

The conductive pillars 20 are preferably formed by electrodeposition of the desired metal (see e.g. US Pat. Nos. 1,354,051 and 2,318,592), although electroless application methods can also be used (e.g. according to US-FSn 3,269,861 and 3,259,559).

Fig. 7 shows an alternative form of printed circuit, in which the conductive pillars 20 do not extend over the surface of the dielectric Extend substrate beyond. Of course, the pillars only need to partially penetrate to extend the substrate provided part of the column opposite to the opposite Surface of the dielectric substrate is exposed.

The i4g. 5 shows a semiconductor element 5o with contact tabs 52, the with the exposed parts 21 of the conductive pillars 20 of the printed circuit are connected. In this figure the semiconductor element is after the end method ("flip-chip bonding") connected to the printed circuit; but it can be also use other fastening methods - e.g. via protruding supply lines ("beam lead bonding") or lead wires ("wire bonding").

Fig. 6 shows another way of carrying out the present invention, i.e. for interconnecting a variety of printed circuit boards. In the form shown, the printed circuits can be stacked on top of each other, whereby the interconnection takes place through conductive pillars 20, which extend through the dielectric substrate extend therethrough to connect to the nearest one Produce patterns of conductive support surfaces.

Claims (7)

Claims 1. Method for @emaining a semiconductor chip on a printed Circuitry made from a thin dielectric substrate with a thin one on its surface conductive layer, characterized in that one (a) the dielectric Provides substrate with a multitude of holes that form a predetermined pattern form, introducing the holes before the conductive layer to one converts predetermined pattern of conductive bearing surfaces, and the holes through extend through the dielectric substrate and with parts of the underside of the conductive layer connected; (b) forms conductive pillars in the holes, which are electrically connected to the underside of the conductive layer and parts of which are exposed to the opposite surface of the substrate, in order to attach further electrical switching elements there, and (c) the contact elements a semiconductor chip with the exposed parts of the conductive pillars. 2. Method of attaching a semiconductor chip to a printed one Circuit that consists of a thin dielectric substrate with one on top of one Surface of the same applied predetermined pattern of conductive bearing surfaces, characterized in that (a) the dielectric substrate having a plurality provided by holes extending through the dielectric substrate and with the underside of at least one part of the conductive bearing surfaces in connection stand with the holes in a predetermined pattern, (b) in the holes guiding pillars formed with the underside e the senior Contact surfaces are in electrically conductive connection and which are partially exposed, to connect further electrical circuit elements, and that one (c) the contact elements a semiconductor chip electrically with the exposed parts of the conductive pillars is present. 3. The method according to claim 1, dadurcij characterized, dal. the conductive pillars extend over the surface of the dielectric substrate 4. Continuous strip with printed circuits, from each of which can accommodate a semiconductor chip, with each printed circuit board made of a thin dielectric substrate with a bead of 2.5 to 25o micrometers exists and has a predetermined pattern of conductive bearing surfaces on a surface of the dielectric substrate are applied, and furthermore the conductive Seating surfaces have a thickness of less than about 125 microns, each of the printed Circuits characterized in that a plurality of conductive pillars extend through the substrate extend with one end at the bottom of a single conductive Contact surface of the predetermined pattern and with this in electrically conductive Connect and to the other end of the opposite surface of the dielectric substrate face exposed, forming the exposed of the conductive pillars form a location that electrically receives a semiconductor element can. 5. Continuous strip with printed circuits according to claim 4, characterized in that the exposed ends of the conductive ouulen each other Extend less than 25o micrometers above the surface of the dielectric substrate. 6. Method of interconnecting a plurality of printed Circuits characterized by (a) a thin dielectric substrate with a conductive layer with a plurality of holes applied to a surface provides, which extend through the dielectric substrate and with the Underside of the conductive layer are connected, the holes in one predetermined Euster are present, (b) forms conductive pillars in the holes, which are in electrically conductive connection with the underside of the conductive layer and each of which has a file open to further electrical circuit elements to connect, (c) form a first printed circuit by cutting the conductive layer converts to a predetermined pattern of conductive bearing surfaces, wherein each part of the underside of the conductive bearing surfaces, which the predetermined Represent patterns in electrically conductive connection with a conductive pillar stands, (d) and the exposed parts of the conductive pillars of the first printed Circuit electrically with a predetermined pattern of conductive contact surfaces second printed circuit connects, the second printed circuit a Has a plurality of conductive pillars extending through a dielectric substrate extend, with one end of each column at the bottom of a single one conductive support surface of the predetermined pattern of support surfaces and with this is in electrically conductive connection and the other ends of the conductive Pillars each on the opposite surface of the dielectric substrate is exposed and allows the connection of further electrical circuit elements. 7. The method according to claim 6, characterized in that one then a semiconductor element electrically connected to the exposed ends of the conductive pillars the second printed circuit connects.