DE4109363C2 - Adhesive connection between an electronic component and a substrate and method for producing the adhesive connection - Google Patents

Abstract

The invention relates to an adhesive connection between an electrical / electronic component and a substrate provided with a conductor track structure or the like, with an electrically conductive first adhesive which is connected to connections of the component and with an electrically insulating second adhesive which is between a fastening surface of the component and a Mounting surface of the substrate is arranged. It is characterized in that the adhesives (8, 11) are designed as hot-melt adhesives and that the first adhesive (8) extends from the connections (3) to connection points (14) of the conductor track structure (12).

Description

State of the art

The invention relates to an adhesive bond between an electrical / electronic component and one provided with conductor track structure or the like Substrate, with an electrically conductive, first Adhesive that is connected to the connections of the component and with an electrically insulating, second Adhesive that is between a mounting surface of the Component and a mounting surface of the substrate is ordered.

From European patent application 0 332 402 it is known between two electrical components to form an adhesive connection. A first glue, which has electrically insulating properties, is in areas of components between these  arranged in which there are no electrical conductor arrangements Find. Wherever there are electrical conductor arrangements of the components opposite, is on the conductor arrangement of one of the components an electrically conductive adhesive is applied in the electrical conductive contact bodies are embedded. These contact bodies are in their protruding area from the electrically conductive body electrically insulating glue embedded and extending up to the conductor arrangement of the other component, that is, they lie to this conductor arrangement so that an electrical contact is produced is posed.

Furthermore, DE 38 44 420 A1 describes a method for connecting Contacts of a first electrical unit to contacts of a known second electrical assembly in which the connection zones of the units are aligned with each other and with one hot melt adhesive provided with electrically conductive particles with the particles in the adhesive initially not permeating are connected to each other in a highly conductive manner. Through pressure and sometimes heating the hot-melt adhesive, which is stripe-shaped between the mutually assigned contacts of the two units arranged net, it is achieved that the conductive particles each between the contacts of the two facing each other in pairs Touch units and so an electrical connection between form these contacts, while the spacing of the particles between the contacts next to each other remain large enough to to prevent a continuous electrical connection. In the zones the adhesive remains between the contacts lying next to each other isolating her.

DE 39 13 115 A1 describes a process for the production of elec trically conductive patterns on substrates known, in which a  photosensitive layer is applied to the substrate, which changes their stickiness by exposure. After generating the klebri A metal-containing powder is applied to the substrate according to the pattern is brought. A heat treatment can remove the sticky pattern removed and the metal powder into a coherent pattern of Conductor tracks are sintered.

DE 37 01 343 C2 describes a method for assembling an IC Building block on a flexible provided with a wiring pattern Known substrate in which a heat seal with the line pattern tel is printed, the connections of the IC module on the lei be applied paste and the connections of the IC module by hot pressing using a heated stamp with the pipe pattern.

The object of the invention is concerned with an adhesive connection between electrical components.

Advantages of the invention

The adhesive device according to the invention with the ge in the main claim mentioned features has the advantage that electri in a simple manner electronic components both assembled and electrical be connected. To do this, two different enamel glue related to different softening temperatures. Preferential the softening temperature of the first is electrically conductive glue is greater than the softening temperature of the second elec trisch insulating glue so that the glue after putting on the Component applied to the substrate at different temperatures can be melted. The first glue extends between the conductor arrangements of the two components and thus represents one electrical connection directly, ie without the intermediary of contact body known from the prior art. The second glue connects a mounting surface of one component with one  Mounting surface of the other component, with a total of one in the Substantial full-surface adhesive assembly is present, on the one hand with means of the first and secondly by means of the second adhesive reali is. For example, simple face-down Assembly of an electrical / electronic component (for example of an IC) on conductor structures of a substrate (for example micro-hybrid or thin-layer hybrid).

Good heat dissipation from the component to the substrate can thereby be achieved be that the second adhesive is an adhesive with a high thermal conductivity ability is. The second adhesive may have metal oxides that are on the one hand electrically insulating, but on the other hand high heat have conductivity.

The first adhesive has one for its electrical conductivity Filler with high electrical conductivity. This filler can preferably be gold or silver.

The invention further relates to a method for producing a Adhesive connection between an electrical / electronic component and a substrate provided with a conductor track structure, wherein an electrically conductive, first adhesive with the connections of the building partly connected and an electrically insulating, second adhesive between a mounting surface of the component and a mounting surface of the substrate is arranged, wherein the first adhesive on the An conclusions and / or on connection points of the conductor structure is brought and then a relative adjustment of component and sub strat and heating up until the softening temperature is reached structures of the hot melt adhesive takes place, a connection of each reached adhesive between the connections and the connection points as well as the mounting surface and the mounting surface and where when two hot melt adhesives are used, the different expansions have temperatures.  

The component is preferably essentially covered over the entire surface of the first and second electrically insulating adhesives on the Glued substrate.

To produce the adhesive connection, it is advantageous if first a photoresist or the like is applied. The photoresist is applied preferably by means of a centrifugal process.

Then the area of the Fo covering the connections tolacks to accept a  sticky condition exposed. The photoresist or the photo coating is thus designed in such a way that their exposure to form a glue structure of the exposed areas. To that The sticky areas formed then become the first Glue applied. This is preferred wise in the state of a powder or granule lats so that when applied to each sticky area a corresponding proportion of he most glue that is not yet in its glue is in good condition, liable; the rest of the Glue that doesn't stick to the sticky areas tet falls from the corresponding surface of the Component down and can be collected and ver be applied.

Then the mounting surface covering portion of the photoresist to accept a sticky state exposed and the second Kle About, preferably also as a powder or as Granules, applied. Also the second adhesive is not in its sticky state that means it has a temperature below the softening temperature. Here too the Excess again from the surface of the component away. In particular, it can be provided that the first or the second adhesive on the component is "shaken".

Finally, the component is then placed on a first one Brought temperature to evaporate the photo lacks leads, this first temperature being lower than the melting temperature is the glue. Here  by removing the photoresist or the like ("baked out").

Then the component is moved to a second height brought here temperature that the melting the glue leads so that the powder or Granules of the two adhesives form a continuous adhesive layer forms. Here is the first Glue on the connections of the component and the second adhesive on the mounting surface. First one and the second adhesive can be directly adjacent to each other Zen. Because the second adhesive is electrically there are no short circuits between adjacent An, wetted with the first adhesive close the component.

The component prepared in this way can then be adhesive assembly on a Substrate are attached. Unless a variety of connected components first for a Kle assembly with the first and the second adhesive is provided, so a separation of the components (for example the IC's) has to be done before the adhesive assembly a separation of the individual prepared components, for example by sawing ner wafer structure or the like.

To now the adhesive assembly of one or more construction to be able to make parts on the substrate first an adjustment between component and sub strat such that the connections of the relationship assign the components in the desired position Conductor structure of the substrate lie.  

After this adjustment, the component is placed on a third temperature heated, which is preferably there through that the component on the on third temperature heated substrate placed becomes. This causes the two to melt ten electrically insulating adhesive, however not the first electrically conductive adhesive melts as it has a higher softening temperature. This forms one flat, thermally well conductive, electrically iso luring adhesive connection between component and sub strat, with the connections of the component ins are especially designed as bump structures due to the application of the first adhesive electrically have conductive adhesive bumps on the conductor Place the web structures of the substrate. The component is then raised to a fourth higher temperature heats that to melt the first glue leads, creating an intimate, electrically conductive Connection between the connections and the conductor web structure is produced. Heating the Component to the fourth temperature can be preferred done wisely via a stamp (Die Stempel), which is an additional amount of heat to reach the fourth temperature.

Subsequently, the ge is then cooled formed circuitry.

Since the connections of the component are within the Outline of the component area (for example one ICs) are required for the connection no additional pads, so that he  considerable space saving compared to conventional len connection procedures (such as bonding, the Bond areas for the bond wires with an equivalent fan out) is given. Against about the known connection method with contact spider saves a lot of space. On Another advantage is that the contact compared to, for example, thin wire or Thick wire bonding - simultaneous through the reflow Gang takes place, so that, for example, many hundreds of conclusions simultaneously, that is, who created at the same time that can. With the second insulating glue, which has a high thermal conductivity, can through the face down assembly of the components their ver pleasure for good cooling towards the Substrate (for example ceramic substrate with base plate) are removed. By using the he mentioned hot melt adhesive has a high elasticity the adhesive bond (around 300%) achieve what almost tension-free assembly. Piezo effects are largely avoided.

Of course, the invention is not based on this limited that the component with photoresist and which he most or second adhesive coated becomes. It is of course the reverse Operation possible, which consists in the sub strat is treated accordingly. It is also possible Lich, both on the component and on the sub strat the adhesive (s) using photoresist bring.

drawing

The invention is described below with reference to the figures explained in more detail. Show it:

Fig. 1 includes a schematic view of a wafer of the mutually coherent component structures,

Fig. 2 coating the wafer of FIG. 2 with Fotolackbe,

Fig. 3 shows the arrangement of Fig. 2 with circuits on components on the applied electrically conductive adhesive,

Fig. 4 shows the arrangement of FIG. 3 between the terminals applied electrically insulating adhesive,

Fig. 5 is a separation of the components of the wafer according to the arrangement of FIGS. 4 and

Fig. 6 is an adhesive assembly of a component on a provided with conductor structures sub strat.

Fig. 1 shows a portion of a wafer 1 , which has integral electronic components 2 , which can be formed, for example, as integrated circuits (IC's). The individual components have connections 3 which are designed as bumps. These bumps are approximately 4 µm high.

Referring to FIG. 2, a photosensitive layer 5, in particular, a photoresist 6 is applied to the underside by overhead Un 4 of the electronic components 2. This is preferably done with a thickness of about 5 microns. In particular, a centrifugal process is used for the application.

The areas 3 of the photoresist 6 covering the connections 3 are then exposed, as a result of which these areas 7 assume a sticky state. The exposure can he follow with a suitable mask. A first adhesive 8 is then applied to the photoresist 6 as granules, preferably shaken up. This first adhesive is electrically conductive; it preferably has a filler with high electrical conductivity, preferably silver or gold. The granules of the first adhesive 8 , which itself is not sticky, adheres when brought on to the sticky areas 7 ; the rest of the granulate slips off the photoresist layer (photoresist 6 ), so that the state shown in FIG. 3 results. As a result, the individual bumps are provided with granules of the first adhesive 8 .

Hereinafter, then - as shown in FIG. 4 - a Be a mounting surface 9 of each component 2-covering of part 10 of the photoresist 6 in a second EXPOSURE process in the tacky state transferred. Then the granules of a second adhesive 11 are applied so that the granules adhere to the adhesive portions 10 of the photoresist 6 . This he follows - as can be seen from Fig. 4 - preference, between the connections 3 of the individual construction elements 2nd

The first adhesive 8 and the second adhesive 11 are hot melt adhesives, which are not sticky in the granular state, but can only be put into the sticky state by appropriate temperature application. The second adhesive is an electrically insulating adhesive.

The wafer 1 is then brought to a first temperature, which leads to the photoresist 6 being “baked out”, that is to say it evaporates.

Then the components 2 are brought to a second tempera ture, which leads to the melting of the adhesives 8 and 11 , so that a continuous adhesive layer forms from the granules of the two adhesives.

According to Fig. 5 then the individual components 2 can be separated by sawing the wafer 1.

To now - according to FIG. 6 - to fix a component 2 on a substrate 13 provided with conductor structure 12 , component 2 is first adjusted relative to the substrate in such a way that the connections 3 of component 2 correspond to corresponding connection points 14 of the conductor structure 12 .

After this adjustment, the component 2 is placed on the substrate 13 heated to a third temperature, the third temperature leading to the melting of the second adhesive 11 , but not to the melting of the first adhesive 8 . For example, the substrate 13 has a temperature of about 150 ° C, so that the melting at low temperature melting adhesive 11 melts and a flat thermally conductive adhesive bond between the component 2 and the substrate 13 is formed. The adhesive bumps formed by the first adhesive 8 are placed on the connection points 14 of the conductor track structure 12 of the substrate 13 . An additional amount of heat is then supplied to the component 2 by means of a stamp, which leads to reaching a fourth temperature, at which the first adhesive 8 melts, which can take place, for example, at approximately 190 ° C., where the adhesive bumps melt and a electrical shear contact between the terminals 3 and the connection points 14 is made.

The thus formed is then cooled Circuit arrangement.

Analogously, the adhesive can also be applied to the substrate 13 in a corresponding manner. Furthermore, it is also possible for the capacitors, SMD quartz crystals, SMD resistors, etc. to be mounted in a corresponding manner (SMD = Sur face mounted device).

Claims (20)

1. Adhesive connection between an electrical / electronic component and a substrate provided with a conductor structure, with an electrically conductive, first adhesive that is connected to connections of the component and with an electrically insulating, second adhesive that between a mounting surface of the component and a mounting surface of the substrate is arranged, the adhesives ( 8 , 11 ) being designed as hot-melt adhesives and the adhesive ( 8 ) extending from the connections ( 3 ) to connection points ( 14 ) of the conductor track structure ( 12 ), characterized in that the two hot melt adhesives ( 8 , 11 ) have different softening temperatures. 2. Adhesive connection according to one of the preceding claims, characterized in that the softening temperature of the first adhesive ( 8 ) is greater than the softening temperature of the second adhesive ( 11 ). 3. Adhesive connection according to one of the preceding claims, characterized in that the second adhesive ( 11 ) has a high thermal conductivity. 4. Adhesive connection according to one of the preceding claims, characterized in that the second adhesive ( 11 ) has metal oxides for its thermal conductivity. 5. Adhesive connection according to one of the preceding claims, characterized in that the first adhesive ( 8 ) has a filler with high electrical conductivity. 6. Adhesive connection according to claim 5, characterized ge indicates that the filler is silver. 7. A method for producing an adhesive connection between an electrical / electronic component and a substrate provided with a conductor structure, wherein an electrically conductive, the first adhesive connected to the connections of the component and an electrically insulating, second adhesive between a mounting surface of the part and a part Mounting surface of the substrate is arranged, wherein the first adhesive ( 8 ) on the connections ( 3 ) and / or on connection points ( 14 ) of the conductor track structure ( 12 ) is applied, the second adhesive ( 11 ) on the mounting surface ( 9th ) and / or the mounting surface ( 15 ) is arranged, then a relative adjustment of the component ( 2 ) and substrate ( 13 ) and heating until the softening temperatures of the adhesive ( 8 , 11 ) formed as a hot melt adhesive are reached and wherein a connection of the softened adhesive ( 8 , 11 ) between the connections ( 3 ) and the connection points th ( 14 ) sow ie the mounting surface ( 9 ) and the mounting surface ( 15 ), characterized in that two hot melt adhesives ( 18 , 11 ) are used which have different softening temperatures. 8. The method according to claim 7, characterized in that the component ( 2 ) is glued substantially over the entire surface by means of the first and the second adhesive ( 8 , 11 ) on the substrate ( 13 ). 9. The method according to any one of claims 7 to 8, characterized in that a photoresist ( 6 ) or the like is applied to the side of the component ( 2 ) having the connections ( 3 ). 10. The method according to claim 9, characterized in that the application of the photoresist ( 6 ) is carried out by a centrifugal process. 11. The method according to any one of claims 9 to 10, characterized in that the connections ( 3 ) covering areas ( 7 ) of the photoresist ( 6 ) are exposed to assume a sticky state. 12. The method according to claim 11, characterized in that on the adhesive areas ( 7 ), the first adhesive ( 8 ), preferably applied as a powder or granules, in particular shaken up. 13. The method according to any one of claims 9-12, characterized in that the portion ( 10 ) of the photoresist ( 6 ) covering the fastening surface ( 9 ) is then exposed to assume a sticky state. 14. The method according to claim 13, characterized in that on the adhesive portion ( 10 ) of the second adhesive ( 11 ), preferably as powder or granules, applied, in particular shaken up, is. 15. The method according to any one of claims 9 to 14, characterized in that the component ( 2 ) is brought to a first temperature which leads to the evaporation of the photoresist ( 6 ), this first temperature being less than the melting temperature of the adhesive ( 8 , 11 ). 16. The method according to claim 15, characterized in that the component ( 2 ) is then brought to a second temperature, which leads to the melting of the adhesive ( 8 , 11 ), so that a continuous adhesive layer forms from the powders or granules . 17. The method according to claim 16, characterized in that after the Ju stierung the component ( 2 ) is placed on the heated to a third temperature substrate ( 13 ), the third temperature for melting the second adhesive ( 11 ), but not to melt on the first adhesive ( 8 ) leads. 18. The method according to claim 17, characterized in that the component ( 2 ) is heated to a fourth temperature, which leads to the melting of the first adhesive ( 8 ). 19. The method according to claim 18, characterized in that the component ( 2 ) via a stamp, the additional amount of heat is supplied to reach the fourth temperature. 20. The method according to any one of claims 7 to 19, characterized in that the connections ( 3 ) are within the outline of the housing of the component ( 2 ), in particular on the housing lower side ( 4 ).