DE102019216720A1 - Method and device for producing an electronic module - Google Patents

Abstract

The invention relates to a method for producing an electronic module. The electronics module has at least one electronic component and a circuit carrier on which the electronic component is arranged. The electronics module also has a molding compound in which the electronic component is at least partially embedded. According to the invention, surface regions of the molding compound that are adjacent to one another have layer thicknesses that are different from one another. In the method of the type mentioned at the outset, the molding compound is irradiated by means of microwave beams and cured as a function of the microwave beams absorbed in the molding compound. Furthermore, in the method, a different radiation dose is sent to the surface areas adjacent to one another, depending on the layer thickness.

Description

State of the art

The invention relates to a method for producing an electronic module. The electronics module has at least one electronic component and a circuit carrier on which the electronic component is arranged. The electronics module also has a molding compound in which the electronic component is at least partially embedded.

From the JP02182438A there is known a method for thermosetting fiber-reinforced plastic which is conductive for microwaves.

Disclosure of the invention

According to the invention, surface regions of the molding compound that are adjacent to one another have layer thicknesses that are different from one another. In the method of the type mentioned at the outset, the molding compound is irradiated by means of microwave beams and cured as a function of the microwave beams absorbed in the molding compound. Furthermore, in the method, microwave beams with different radiation doses are transmitted to the surface areas adjacent to one another as a function of the layer thickness.

In this way, depending on the layer thickness of the surface areas of the molding compound, in particular epoxy resin molding compound, a radiation dose can advantageously be sent which is sufficient to crosslink the molding material sufficiently. In a further advantageous manner, overheating and damage to the mold material by microwaves cannot take place in thin layers. This is because it was recognized that when the molding compound is hardened by means of microwaves, the molding compound can be damaged if the radiation dose is too high. The mold compound, in particular HCD compound (HCD = Hard Cover Dispensed), is preferably formed by a resin, in particular epoxy resin or polyester resin. The molding compound preferably has filler particles, in particular ceramic particles.

In a preferred embodiment of the method, a radiation filter is placed between a radiation source and the surface areas of the molding compound, at least two adjacent filter surface areas of the radiation filter having mutually different extinction properties for the microwave rays, so that microwave rays passing through the radiation filter have different attenuation within the surface areas Experienced. Advantageously, the mutually different surface areas of the molding compound can be cured by means of a radiation filter, in particular of flat design, with different irradiation intensities.

In a preferred embodiment, the radiation filter has a fluid which is designed to weaken the microwave rays as they pass through the radiation filter. The filter surface areas of the radiation filter that are adjacent to one another preferably each have the fluid. The fluid preferably has water or an oil, for example a fatty acid ester, in particular pentaerythritol ester, more preferably the fluid is formed by water or oil. The fluid is preferably designed to absorb the microwave rays and / or to scatter the microwave rays. Fluid molecules of the fluid are preferably designed to be polar for this purpose.

The radiation filter can thus advantageously be provided at low cost. The radiation filter can also advantageously be cooled in so far as the filter medium itself is designed to absorb heat and can be cooled as a fluid in a fluid cooler.

In a preferred embodiment of the method, the fluid is conducted in a fluid circuit, and heat absorbed in the fluid is removed from the fluid. A fluid temperature can advantageously be kept constant in this way. The fluid can be kept in a fluid circuit, for example, by means of a fluid medium pump. The fluid can be pumped into the radiation filter by the fluid medium pump, for example through an inlet opening, pass through the radiation filter and exit the radiation filter again through an outlet opening. The fluid can then flow further through a heat exchanger which is designed to dissipate heat from the fluid. The fluid can flow from the heat exchanger back to the fluid medium pump. The radiation filter can thus advantageously be cooled at low cost.

The invention also relates to a device for curing molding compound on an electronics module. The device comprises a radiation transmitter for microwaves and a holding device for holding an electronic module. The radiation transmitter is designed and arranged to generate microwave beams and to transmit them in the direction of the holding device or onto the holding device. The device also has a radiation filter, which is arranged in the beam path between the radiation transmitter and the holding device, or can be arranged there.

The radiation filter has at least two filter surface areas which are designed for the passage of radiation and each form a partial filter are designed to weaken the microwave rays incident on the radiation filter with mutually different degrees of attenuation. The radiation filters preferably each have mutually different extinction properties, in particular absorption properties or scattering properties. The partial filters further preferably each have different layer thicknesses of a filter layer forming the partial beam filter. The weakening effect of the partial filters can thus advantageously be determined, for example, by means of a radiation law according to Lambert-Beer.

In a preferred embodiment, the radiation filter has a container in which a fluid that weakens the microwave rays is received. The container is preferably made of glass, in particular quartz glass, or a plastic that is translucent for the microwave rays. In this way, the radiation filter can advantageously be provided in conjunction with cooling at low cost.

The sub-filters preferably each have a different layer thickness from one another. The sub-filters advantageously each have mutually different extinction properties for the microwave rays. The fluid is preferably water or an oil. In this way, the microwave beams can advantageously be filtered at low cost.

In a preferred embodiment, the sub-filters are each formed by a part of a container wall of the container, the container wall having a topography corresponding to the filter thickness of the sub-filters. The container wall of the container can advantageously be formed, for example, by a deep-drawn plastic or by blown glass. The container preferably has a further container wall spaced apart from the container wall forming the partial filter, the container walls enclosing a cavity between one another. The cavity is designed for guiding the fluid. The further container wall can, for example, be flat. The further container wall can thus be formed, for example, by a flat glass plate or plastic plate.

The container wall in which the sub-filters are formed can thus have a wall area for each sub-filter which is at a predetermined distance from the further container wall. The container wall preferably has a topography, in particular surface geometry, that corresponds to the electronics module. Preferably, at least two wall areas of the container wall forming the partial filters are spaced differently from the further container wall. Thus, the fluid in the sub-filters can have a different layer thickness from one another.

In a preferred embodiment, the device is designed to guide a fluid flow through the radiation filter, the container having a fluid inlet opening and a fluid outlet opening for this purpose. The device is preferably designed to guide the fluid flow in a fluid circuit, and for this purpose has a fluid medium pump.

A frequency of the microwaves is preferably between 500 megahertz and 300 gigahertz.

The microwave transmitter is formed, for example, by a traveling wave tube, a klystron, a twystron or a gyrotron, in each case for generating the microwave beams.

• 1 zeigt ein Ausführungsbeispiel für eine Vorrichtung und ein Verfahren zum Härten von Mold-Masse an einem Elektronikmodul mittels Mikrowellenstrahlen, bei dem die Mikrowellenstrahlen für Bereiche der Moldmasse mit zueinander verschiedener Dickenerstreckung bis zu einem Bauteil oder einem Schaltungsträger hin mit einer der Dickenerstreckung entsprechenden Bestrahlungsstärke bestrahlt werden kann, was durch ein der Topografie des Elektronikmoduls entsprechend ausgebildetes Strahlenfilter bewirkt werden kann.

The invention will now be described below with reference to figures and further exemplary embodiments. Further advantageous design variants result from a combination of the features described in the dependent claims and in the figures.

• 1 shows an embodiment of a device and a method for curing molding compound on an electronic module by means of microwave beams, in which the microwave beams for areas of the molding compound with mutually different thicknesses up to a component or a circuit carrier can be irradiated with an irradiance corresponding to the thickness which can be achieved by a radiation filter designed to match the topography of the electronics module.

1 shows an embodiment of a device and a method for curing molding compound on an electronics module by means of microwave beams. The device 1 includes a transmitter 2 for microwave rays 3 . The transmitter 2 is formed, the microwave rays 3 to generate and in the direction of a holding device 4th , especially in one between the transmitter 2 and the holding device 4th arranged cavity 33 to send.

The holding device 4th comprises in this example a circumferential collar 5 , in which a radially inwardly pointing recess is formed so that a support shoulder is provided in the area of the recess on the collar 6th for an electronic module 7th is formed. In another embodiment, the holding device can have webs or supports which are designed to hold the electronics module.

The electronics module 7th has a circuit carrier 8th , in particular printed circuit board or ceramically designed circuit carrier, for example DCB substrate (DBC = Direct Copper Bonded), LTCC substrate (LTCC = Low-Temperature-Cofired- Ceramics), AMB-Substrate (AMB = Active-Metal-Brazed) or IMC-Substrate (IMC = Insulated-Metal-Substrate).

The electronics module 7th also has two electronic components 9 and 10 on, with the components 9 and 10 , for example a microprocessor or a semiconductor switch or a capacitor, each have a mutually different height extension. The components 9 and 10 are with the circuit carrier 8th connected, in particular soldered. The components 9 and 10 are in this embodiment from a mold compound 11 covered, in particular embedded in this.

The mold mass 11 has one extending over a surface of the circuit board 8th extending uniform height extension 21st on. The thickness extension 22nd the mold mass 11 which the component 9 covered, is designed to be smaller than the thickness extension of the mold mass 11 , which is the circuit carrier 8th covered and there the height extension 21st corresponds to. A thickness extension 23 the mold mass 11 which the component 10 covered, is formed smaller than a thickness extension 22nd , and also smaller than that of the vertical extension 21st corresponding thickness extension of the mold compound 11 that is the circuit carrier 8th covered.

In the beam path between the transmitter 2 and the holding device 4th , and so also the electronics module 7th , is a radiation filter 13th for the microwave rays 3 arranged. The radiation filter 13th comprises a container which is formed from two container walls which are each deep-drawn or blown.

The radiation filter 13th , which in this embodiment by one for the microwave beams 3 translucent container is formed, comprises a container wall 14th . The container wall 14th has two surface areas in this exemplary embodiment 16 and 17th on, which are each designed as a particular concave or hollow recesses in the container wall 14th are trained. The container wall 14th is by means of a distance 18th from another container wall 15th , which is flat in this embodiment, spaced. So is between the container walls 14th and 15th enclosed a cavity in which a fluid 32 is recorded.

The container including the container walls 14th and 15th , has an inlet port 25th for the fluid 32 and an outlet port 26th for the fluid 32 on. The fluid 32 so can the radiation filter 13th happen. The area 17th the container wall 14th shows a greater distance 19th to the further container wall 15th on than the the area 17th surrounding container wall 14th . The area 16 , which as a recess in the container wall 14th is formed, points to the further container wall 15th a greater distance 20th on than the distance 18th the container wall 14th to the further container wall 15th down.

The fluid 32 has in this embodiment one for the microwave beams 3 debilitating property. The fluid 32 is designed, for example, the microwave rays 3 when passing through the fluid 32 to absorb or scatter at least partially or only partially.

The radiation filter 13th points so in the area 17th a stronger extinction effect for the microwave rays 3 on than in which the surface area 17th surrounding area of the filter 13th with the thickness extension 18th .

The area 16 In this exemplary embodiment, it has a greater extinction effect for the microwave rays 3 on than the surface area 17th . The areas 16 and 17th form a sub-filter of the filter in this exemplary embodiment 13th . A topography of the filter 13th , especially the container wall 14th With the different filter thicknesses formed there, it can be adapted to a topography of the electronics module, so that through the filter 13th a radiation filter adapted to the layer thickness of the molding compound is formed.

The microwave rays 3 , which on the radiation filter 13th meet, pass through for the microwave rays 3 translucent container wall 14th , and are in the fluid 32 in the area of the surface area 17th , and so of the partial filter, weakened and continue to emerge from the radiation filter through the further container wall 15th which for the microwave rays 3 is translucent than weakened microwave rays 3 " from the radiation filter 13th out again. The microwave rays 3 which are placed on the radiation filter in the area of the container wall 14th hit when passing through the filter 13th with the thickness extension 18th through the fluid 32 weakened, and occur on the back of the filter, formed by the further container wall 15th , as weakened microwave rays 3 ' out again. The microwave rays 3 occur after passing through the surface area 16 , which is a partial filter for the microwave rays 3 forms than weakened microwave rays 3 ''' from the radiation filter 13th out again.

The weakened microwave rays 3 ' are formed, the mold mass 11 with the thickness extension 21st in particular to cure completely. The mold mass 11 which the component 10 covered, has a smaller extent of thickness 23 on. The weakened microwave rays 3 ''' , which by the partial filter, formed by the surface area 16 of the filter 13th have been weakened, are sufficient to maintain the mold mass 11 which the component 10 covered to cure. The microwave rays 3 , or the microwave rays 3 ' , which each have a greater radiation intensity than the weakened microwave rays 3 ''' , would the mold bulk 11 that the component 10 covered, not only harden, but further damage after hardening.

The microwave rays 3 '' , generated by the radiation filter, formed by the surface area 17th , are formed, the mold mass 11 which the component 9 covered to cure.

The microwave rays 3 meet at the in 1 device shown 1 in a projection through the radiation filter 13th through to the mold compound 11 of the electronics module 7th . The microwave rays 3 experienced when passing through the filter 13th , and so also when passing through the in the radiation filter 13th absorbed fluids 32 - depending on the thickness extension 18th , 19th or 20th the area of the filter 13th -, a mutually different weakening, produced by the extinction effect of the fluid 32 . The microwave rays 3 are called weakened microwave rays 3 ' , 3 '' or 3 ''' on the electronics module 7th , and there on the mold mass 11 , projected.

The fluid 32 can when passing through the filter 13th Radiant energy from the microwave rays 3 absorb and convert it into heat, especially low-temperature heat. The fluid 32 flows in this embodiment in a fluid circuit.

The fluid circuit includes a fluid pump 24 , a heat exchanger 27 and a container 31 in which the fluid 32 is kept in stock.

The fluid pump 24 is on the fluid outlet side by means of a fluid line 28 with the inlet port 25th of the filter 13th connected. The outlet opening 26th of the filter 13th is by means of a fluid line 29 with the heat exchanger 27 connected. The heat exchanger 27 is by means of a fluid line 30th with the container 31 connected. The container 31 is by means of a fluid line 34 with the fluid pump 24 connected.

The device 1 also includes a processing unit 12th , which is formed for example by a microcontroller or a microprocessor. The processing unit 12th is via a connecting line 35 on the output side with the fluid pump 24 connected and formed, a control signal for activating the fluid pump 24 and this via the connection line 35 to the fluid pump 24 to send. The processing unit 12th is via a connecting line 36 with the radiation transmitter 2 for the microwave rays 3 connected and formed, a control signal for activating the microwave transmitter 2 and this via the connection line 36 to the microwave transmitter 2 to send.

To an operation of the device 1 can the processing unit 12th the control signal for activating the fluid pump 24 generate so that the fluid 32 from the container 31 via the fluid line 28 through the radiation filter 13th can be pumped through, so that the fluid 32 the radiation filter 13th happens. After the fluid circuit has been activated, the processing unit 12th the control signal for activating the microwave transmitter 2 generate so the microwave transmitter 2 the microwaves depending on the received control signal 3 generate and into the cavity 33 can send out.

The microwave rays 3 can in the radiation filter 13th by the fluid flowing there 32 weakened, especially from the fluid 32 at least partially absorbed. The so by the extinction effect of the fluid 32 weakened microwave rays 3 ' , 3 '' and 3 ''' can each have different layer thicknesses of the mold compound 11 cure with the appropriate radiation dose, corresponding to the weakened microwave rays.

That in the radiation filter 13th heated fluid 32 can in the heat exchanger 27 , which has, for example, a cooling device, in particular a forced convection cooling device with air cooling or fluid cooling, so that the fluid 32 absorbed heat via the heat exchanger 27 can be discharged. That in the heat exchanger 27 cooled fluid can be via the fluid line 30th back in the container 31 flow.

The fluid 32 can - unlike in 1 shown - not flow in a closed fluid circuit. The fluid 32 can for example be provided by a fluid source, for example a water inflow line, and to the inlet opening 25th be directed. That from the outlet 26th Exiting fluid can for example be conducted into a drain, in particular a drain line.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 02182438 A [0002]

Claims (12)

Method for producing an electronic module (7), wherein the electronic module (7) has at least one electronic component (9, 10) and a circuit carrier (8) on which the component (9, 10) is arranged, and a molding compound (11) which at least partially embeds the electronic component (9, 10), characterized in that adjacent surface areas of the molding compound (11) have mutually different layer thicknesses (21, 22, 23), the molding compound (11) being used in the method by means of microwave rays ( 3, 3 ', 3'',3''') is irradiated and cured depending on the microwave rays (3, 3 ', 3'',3''') absorbed in the molding compound (11), with the method Depending on the layer thickness (21, 22, 23), microwave beams (3 ', 3'',3''') with different radiation doses are transmitted onto the adjacent surface areas. Procedure according to Claim 1 , characterized in that in the method a radiation filter (13) is introduced between a radiation source (2) and the surface areas of the molding compound (11), at least two adjacent filter surface areas (14, 16, 17) of the radiation filter (13) different from one another Have extinction properties, so that microwave rays (3 ', 3 ", 3"') passing through the radiation filter (13) experience a mutually different attenuation within the surface areas (14, 16, 17). Procedure (1) according to Claim 1 or 2 , characterized in that the radiation filter (13) has a fluid (32) which is designed to weaken the microwave rays (3, 3 ', 3 ", 3"') when the fluid (23) passes through. Method according to one of the preceding claims, characterized in that the fluid (32) comprises water or oil. Method according to one of the preceding claims, characterized in that the fluid (32) is guided in a fluid circuit (13, 28, 29, 27, 30, 31, 34) and heat absorbed in the fluid (32) from the fluid ( 32) is discharged. Device (1) for curing molding compound (11) on an electronic module (7), comprising a radiation transmitter (2) for microwaves (3, 3 ', 3 ", 3"'), and a holding device (4, 5) for holding an electronic module (7), the radiation transmitter (2) being designed and arranged to generate microwave beams (3, 3 ', 3 ", 3"') and in the direction of the holding device (4, 5) or onto the To send holding device (4, 5), and a radiation filter (13) which is arranged in the beam path of the microwave beams (3, 3 ', 3' ', 3' '') between the radiation transmitter (2) and the holding device, and the Radiation filter (13) has at least two surface areas (14, 16, 17) designed for the passage of rays and each forming a partial filter (14, 16, 17), each of which is designed to have mutually different microwave rays (3) incident on the radiation filter (13) To weaken degrees of weakening. Device (1) according to Claim 6 , characterized in that the radiation filter (13) has a container (14, 15) in which a fluid (32) weakening the microwave rays (3) is received. Device (1) according to Claim 6 or 7th , characterized in that the sub-filters (14, 16, 17) each have a mutually different layer thickness (18, 19, 20). Device (1) according to Claim 7 or 8th , the fluid (32) is water or oil. Device (1) according to one of the Claims 6 to 9 , characterized in that the sub-filters (14, 15, 16) are each formed by a part of a container wall (14) of the container (14, 15), the container wall (14, 16, 17) having one of the filter thicknesses of the sub-filters (16 , 17) has a corresponding topography. Device (1) according to Claim 10 , characterized in that the container wall (14, 16, 17) has a topography corresponding to the electronics module (7). Device (1) according to one of the Claims 6 to 10 , characterized in that the device (1) is designed to guide a fluid flow through the jet filter (13) and the container (14, 15) has a fluid inlet opening (25) and a fluid outlet opening (26) for this purpose.

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