DD264785A1 - METHOD FOR PRODUCING CERAMIC MULTILAYER STRUCTURES - Google Patents

Abstract

The invention relates to the production of o. G. Structures such as ceramic housing or multi-level wiring by means of laser beam, starting from green ceramic films of an inorganic powdered ceramic material mixed with an organic binder, applied to the ceramic or metallic layers and then laminated, sintered into a unit and then by breaking be brought into the required geometry. Deformations, dimensional deviations and leaks should be avoided. According to the invention, this is achieved by sintering a network of intersecting lines onto the surfaces of the still green film laminate with a laser beam of low energy density (0.5 to 10 mWS) and, after sintering the entire film laminate, breaking the film laminate along the sintered line network.

Description

Title of the invention

Process for producing ceramic weir structures by means of a laser beam

Field of application of the invention

The invention relates to a method for producing ceramic multilayer structures by means of a laser beam, starting from green ceramic films of an inorganic powdered ceramic material in admixture with an organic binder, applied to the ceramic or metallic layers and then laminated, sintered in one unit and then be brought into the required geometry by breaking. These multilayer structures are used, for example, as ceramic housings for accommodating integrated Si chips or as multi-level wiring substrates in the field of hybrid technology.

Characteristic of the known state of the art

It is known in the manufacture of ceramic multilayer structures of successive Einzelschich'en z. B. silk screen printed or ceramic intermediate layers can wear, go out and squeeze in the unsintered state using pressure and possibly heat (laminating) (DE-A? 2 703 956).

It proves to be disadvantageous that the Druckkriifte not only deform the surface layer ^, but cause within the individual layers plastic deformation. This is particularly the case when the individual elements by recesses in the surface (windows, breakthroughs) or by special surface profiles (conductor tracks,

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Webs) can transmit the one-sided pressure only over web-like areas. The locally increased stress concentrations produce regions of different densification in the next lower layer. Heated or reduced lamination tools tried to overcome these disadvantages (DE-AS 1 765 980, 1 944 618).

It is also known to design the lamination process to the effect that the Einl ^ lschichten incorporated in solvent vapors or that they are previously moistened with solvents (DE-OS 2,011,628). In the case of lamination, however, such a procedure can lead to considerable dimensional deviations due to the plastic softening of the binder. The same applies to the moistening of the film surface before lamination (DD 115 105), where also still lamination templates are required. Therefore, attempts have been made to completely bypass the lamination process in that the individual ceramic insulation layers are formed in the screen printing method from a suitably plastically plasticized mass (DE-AS 2 337 141). However, this approach is generally only suitable for cover layers, since the screen printing layers can not be printed again without further metallic circuit traces or -er insulation resistance of the layer is not sufficient. For the reasons mentioned above, preference is frequently given to the method which works with a lamination process. At the same time or after lamination, a score grid is printed with corresponding tools in the still unsintered and thus raw film. After the sintering process, the separation of the components takes place by breaking apart along these score lines (DD 246 273). Such tools rapidly wear due to the small grid dimensions. The compression differences caused by the pressing in lead to a strong burr formation along the score lines and, correspondingly, unclean fracture surfaces. Other;. 3 βΊ ^ s, it is also known to introduce the said score lines in the already sintered state. This is done with ultrasound (US 3 970 819). The i

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Laser beams have a very high energy density> 100 mWs). In the used sintered AlgO ^ bodies, however, cracks were often observed after the laser processing, because of high temperature gradients caused high tensile stresses to which the ceramic material is not equal. After the breakup, uneven fracture surfaces, ζ, often arise in this case as well . T. have burnt pores or craters.

Object of the invention

The object of the invention is to avoid deformation, deviations and leaks caused by the production of multilayer structures.

Explanation of the essence of the invention

The invention is therefore based on the object to develop a method for producing ceramic multilayer structures by means of laser beam, which is based on green ceramic films of an inorganic pulverfb'rmigen ceramic material in admixture with an organic binder, applied to the ceramic or Metalliscne Schi «th and then laminated, sintered into a unit and then brought into the required geometry by breaking. For the stress reduction and for the homogenization of the later edge regions of the singulated multilayer structures, a laser + rahl is to be used, which converts the binders of the ceramic into the gaseous state in the processing area even before the actual sintering of the film laminate.

Therefore, according to the invention, a network of intersecting lines is formed on the surfaces of the still green foil laminate with a laser beam of low energy density (0.5 to 10 mWs)

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sintered and after the sintering of gesamtan film laminate broken the film Foliarilaminat along the sintered line network.

For this laser machines are used whose wavelength depends on the ceramic components bzv /. the binders are well absorbed.

It is advantageous to choose the energy density of the laser beam proportional to the degree of polymerization of the oragnisches binder used, because in this way an optimal sintering process is ensured.

The inventive method causes a pre-sintering of the film laminate along the later fault lines, which at the same time form the Rände.o the later isolated components.

The net-like pre-sintering eliminates adverse effects of the lamination process in the form of internal stresses in these particularly critical edge regions, so that deformations, dimensional deviations and leaks in the components are avoided. In connection with the subsequent sintering of the entire film laminate may be. Erupted defects, open pores, etc. healed. The later breakage edges of the sintered film laminate are therefore very even and even with no burr.

embodiment

For the manufacture of ceramic packages which are to receive integrated circuits, a film laminate of three film layers with a total thickness of 1.5 mm (0.5 mm in each case) is assumed. These films consist of a 94% strength Al.sub.2 O.sub.4 ceramic with a binding agent content of 5% by weight based on polyvinyl acetate in order to achieve flexibility. After applying the metallic interconnects by Siebdruokprozesse these films are stacked congruent and under a pressure of 10 Mpa

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laminated. In the unsintered "green" film state, the film laminate is exposed to a longitudinally excited, electrically controllable COp gas laser, which generates pulses of energy 10 mV / s and the length 100 μβ, the wavelength 10.6 ] xm and the repetition frequency of 1 kHz. Then, a focus is made on a diameter of 120 pm on the film laminate. The film laminate v / ird with a

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Speed of 75 mms moves. The movement and impulse control of the laser are program-controlled. In this way, in the film laminate, a line network of eingelnter ^x , whose lines are in cross section 0.15 _ + 0.02 mm wide and correspond to the desired geometry of the components. This line network will be from both sides of the

Sintered olienlaminats. Only the Einsinterung cHeses NaOH pattern followed by the actual sintering of the Folienla.ir'.nats in the oven at a temperature of 1500 ⁰ C and 2 h hold time in a wet forming gas.

After cooling, the sintered film laminate on the sintered lines can be easily broken into the required geometries of the housing.

Claims (2)

wits - 1 - P 1327 claims A method of making ceramic merlayer structures by laser beam, starting with ceramic green sheets of an inorganic powdered ceramic material in admixture with an organic binder to which ceramic or metallic layers are applied and then laminated, sintered into a single and subsequently broken into the required geometry is achieved ^, characterized in that a network of intersecting lines is sintered onto the surfaces of the still green foil laminate with a laser beam of low energy density (0.5 to 10 mWs) and the foil laminate is sintered along the entire foil laminate sintered line network is broken. 2. The method according to claim 1, characterized in that the energy density.e of the laser beam is selected in proportion to the degree of polymerization of the organic binder used.