RU2752013C1 - Method for manufacture of microassembly of frameless electronic components on flexible organic substrates - Google Patents

Abstract

FIELD: electric elements.SUBSTANCE: invention relates to microassembly, particularly, to a technology for installation of a frameless electronic component base on flexible substrates. The technical result is achieved by creating multilayer switching with formation of electrical contacts with the leads of frameless electronic components (FEC) the crystals whereof are pre-thinned to a thickness of less than 100 mcm and installed on the adhesive with leads facing upward on a flexible organic substrate. The height difference at the interface of the FEC and the substrate is leveled by local application of layers of dielectric material along the perimeter around the FEC by a method of ink jet printing, gradually increasing the perimeter of the printing area, wherein a the step at the interface of the component and the substrate is gradually smoothed with formation of a uniform smooth surface for formation of a multilayer commutation, whereon the lower switching layer providing electrical connection of the FEC leads with the multilayer switching is applied. Then dielectric and conductive layers are consequently applied by a method of inkjet printing to create multilayer switching. Windows are therein left in the dielectric layers during printing, by means whereof electrical contact between the levels of multilayer commutation is provided.EFFECT: provided are flexibility of the resulting product and reduction of thickness thereof during manufacture of microassembly of frameless components on flexible substrates.1 cl, 1 dwg

Description

The proposed technical solution relates to microassembly, in particular to the technology of mounting an unpackaged electronic component base on flexible substrates.

A known method of mounting electronic components with ball leads, presented in the RF patent RU 2331993 C2, in which the mounting is carried out by the inverted crystal method, including the installation of the component on the mounting surface of the substrate and melting the solder balls. However, the known method has significant disadvantages:

- the method is not suitable for mounting on low-temperature organic substrates, including polyethylene naphthalate (PEN), since the basic process is high-temperature heat treatment to create soldered joints of a component with current-carrying layers;

- the method leads to an increase in the thickness of the product over the length of the layer of molten ball leads and solder;

- the method requires high-precision alignment of the electronic component with multilayer commutation during installation in order to achieve the required electrical contact.

There is also a known method of manufacturing a microelectronic unit on a plastic base (RF patent RU 2597210 C1), according to which a multichip module is manufactured by pouring unpackaged electronic components with an organosilicon polymer to form a planar structure in the form of crystals of unpackaged electronic components integrated into the substrate for their subsequent switching. The disadvantage of this method is the need for high-temperature treatment of the organosilicon polymer at the stage of hardening (up to 250 ° C), which significantly limits the range of compatible materials, increases the rigidity of the entire structure and makes high demands on the technology of ensuring the flatness of the polymer surface during its application and after heat treatment, taking into account further use as a basis for the implementation of metal wiring.

The closest technical solution (prototype) is a method for embedding a component in a base and forming an electrical contact with a component, described in RF patent RU 2297736 C2, which is a method for manufacturing a microassembly of unpackaged electronic components on flexible organic substrates, including creating multilayer switching and forming an electrical contact between multilayer switching and leads of electronic components. In the proposed method, a microrelief is actually formed in the substrate in the form of cavities in which the components are placed, and then the free volume of the cavity is filled with resin to fix the unpackaged components inside the substrate. After that, switching is applied on the surface of the resulting pseudoplanar structure.

The disadvantage of this method is the need to implement the operation of forming cavities in the substrate and ensuring the flatness of the surface when filling the resulting cavities with resin. In addition, the heterogeneity of the substrate obtained in this way reduces the mechanical strength of the product as a whole, including with respect to flexibility, and also limits the possibility of using ultrathin substrates to create the product, since the fixation of the unpackaged electronic component in the substrate is carried out due to the adhesion of its end to the filler (resin ), as well as a filler with a substrate along the boundary of the formed cavity.

The objective of the claimed invention is to create a method that makes it possible to manufacture ultrathin hybrid assemblies based on thinned crystals of unpackaged electronic components on flexible organic substrates to enable their further conformal integration into functional products.

The technical result obtained when solving this problem is to simplify the technology for manufacturing microassembly of unpackaged components on flexible substrates, while achieving flexibility of the resulting product and reducing its thickness.

The specified technical result is achieved due to the fact that in the method of manufacturing a microassembly of unpackaged electronic components on flexible organic substrates, including the creation of multilayer switching with the formation of electrical contacts between multilayer switching and the leads of unpackaged electronic components, crystals of unpackaged electronic components, pre-thinned to a thickness of less than 100 μm, are installed onto the adhesive with leads upwards onto a flexible organic substrate, then the height difference at the border of the unpackaged electronic component and the substrate is leveled by local ink jet printing along the perimeter around the unpackaged electronic component of layers of dielectric material with a gradual increase in the perimeter of the printing zone, at which, due to overlap with the previous layer of the deposited dielectric material, there is a gradual smoothing of the step at the interface between the component and the substrate; f the leveling layers of the dielectric material, except for the latter, are cured by ultraviolet radiation to achieve the maximum layer thickness, the last layer is hardened, as a result of which a uniform smooth surface is formed to form a multilayer commutation, on which the lower commutation layer is applied with conductive ink with a sintering temperature of less than 150 ° C, providing electrical connection of the leads of unpackaged electronic components to multilayer commutation, then by the method of ink jet printing, the sequential deposition of dielectric and conductive layers is carried out to create multilayer commutation, while in the process of printing, windows are left in the dielectric layers through which electrical contact between the levels of multilayer commutation is ensured.

This method is based on the use of ink jet technology for the formation of multilayer switching on flexible substrates with crystals of electronic components placed on them, preliminarily thinned to a thickness of less than 100 microns. In this case, the formation of the commutation and the electrical connection of the component is carried out simultaneously in a single cycle of the inkjet printing process. The choice of the substrate material is insignificant for the process; it can be carried out both with a rigid base (for example, FR4 textolite), and with the use of an ultrathin flexible organic substrate (for example, a PEN film with a thickness of 30 μm). The possibility of using organic polymers as a substrate material is ensured by the fact that the proposed method uses only low-temperature processes (up to 150 ° C).

After placing and fixing the electronic component on the substrate to provide subsequent access to the terminals of the electronic component and its conformal mechanical fixation on the substrate, the surface is pseudoplanarized by leveling the height difference at the interface between the component and the substrate. For this, layers of dielectric material are applied around the component with a gradual increase in the perimeter of the print zone using the drop-jet method, while, due to the overlap with the previous layer, the steps at the interface between the component and the substrate are gradually smoothed. All dielectric alignment layers are applied with UV curing after each printing pass to achieve maximum layer thickness, and the last layer is applied with exposure after printing. In this case, the surface relief is smoothed due to the increased spreading time of the ink and a homogeneous smooth surface is formed, which is required for the formation of multilayer commutation.

The resulting surface is suitable for printing the lower switching layer, and the applied layer also provides the electrical connection of the leads of the electronic component to the switching. The use of conductive ink with a sintering temperature of less than 150 ° C makes it possible to implement the process on ultrathin organic substrates, since their annealing does not damage the substrate.

Further, within the framework of the unified inkjet technology, it is possible to further sequentially increase the number of conductive and dielectric layers to create multilayer switching. In this case, windows are left in the dielectric layers, areas in which no material is applied, providing electrical contact between the switching layers. Received; in the above way multilayer switching is possible installation of the basic components of the circuit.

The invention is illustrated in FIG. 1 (a, b, c, d, e, f) is a sequence of technological operations of a method for manufacturing a microassembly of unpackaged electronic components on flexible organic substrates.

Micro-assembly (Fig. 1) contains:

1 - organic polymer substrate,

2 - adhesive layer,

3 - unpackaged electronic component,

4 - conclusions of the electronic component,

5 - aligning dielectric structure,

6 - lower layer of multilayer commutation,

7 - dielectric layer (interlayer insulation of multilayer commutation),

8 - the second layer of multilayer commutation.

An example of the implementation of the technological process is shown in Fig. 1 and depicts the entire technological process according to the invention. Next, the process depicted in FIG. 1 is considered in stages.

At stage A (Fig. 1A), an adhesive 2 is locally applied to the original organic substrate 1, for example, from PEN, in the area of the intended mounting of unpackaged electronic components by any of the known available methods.

The placement and fixation of the unpackaged electronic component 3 is performed at stage B (Fig. 1B). The thinned crystal of the component is installed on the adhesive on the substrate with the leads 4 upwards, after which the adhesive 2 is hardened.

At stage B (Fig. 1B), the surface is pseudo-planarization by local drop-jet deposition along the perimeter around the component of the set of dielectric layers 5 with a sequential decrease in their number as the distance from the end face of the component increases. After each pass, all but the last layers are cured to reduce bleeding and gain height. The last layer is hardened at the end of the printing process to obtain a smooth pseudo-planar surface.

Further (Fig. 1D), ink jet printing of the lower layer of multilayer switching 6 is performed, and simultaneously with the formation of switching in the process of printing with conductive ink, the switching contact with the electrical terminals of the component is realized.

After that, dielectric 7 (Fig. 1D) and conductive 8 (Fig. 1E) layers are sequentially deposited, forming a multilayer switching structure. To ensure contact between the switching layers, in the process of printing the dielectric layers, windows are created that communicate between the switching levels.

As a result, an ultrathin microassembly was made based on thinned crystals of unpackaged electronic components on a flexible organic substrate, which has flexibility within the flexibility of an electronic component.

Claims (1)

A method of manufacturing a microassembly of unpackaged electronic components on flexible organic substrates, including the creation of multilayer switching with the formation of electrical contacts between multilayer switching and the leads of unpackaged electronic components, characterized in that crystals of unpackaged electronic components pre-thinned to a thickness of less than 100 microns are mounted on the adhesive with the leads upward on the flexible organic substrate, then the height difference at the border of the unpackaged electronic component and the substrate is leveled by local ink jet printing along the perimeter around the unpackaged electronic component of layers of dielectric material with a gradual increase in the perimeter of the printing zone, at which, due to overlap with the previous layer of applied dielectric material, gradual smoothing occurs steps at the interface between the component and the substrate, while after each printing pass, all the alignment layers of the dielectric material and besides the last one, they are cured with ultraviolet radiation to achieve the maximum layer thickness, the last layer is hardened, as a result of which a uniform smooth surface is formed for the formation of multilayer switching, on which the lower switching layer is applied with conductive ink with a sintering temperature of less than 150 ° C, providing electrical connection of the terminals dielectric and conductive layers are sequentially applied to create multilayer commutation by ink jet printing, while the printing process leaves windows in the dielectric layers through which electrical contact between the multilayer commutation levels is ensured.

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