Method for sintering electronic components on substrate, sintering press and press assembly thereof

Abstract

A press assembly (14) for a sintering press comprises: a multi-rod cylinder (20) having a front head (22) and a rear head (24), the front head and the rear head together defining a compression chamber (26). In the front head (22), press rods (28) are slidably supported in a manner parallel to and independently of each other, and the rear ends of the press rods protrude into the compression chamber (26). In the compression chamber (26), an actuating flat washer (30) extends over the rear end of the press rod. The actuating flat washer (30) is fixed to the front head by an anchoring frame (34), the anchoring frame engaging the peripheral portion (30') of the actuating flat washer (30), and the anchoring frame (34) is completely accommodated in the compression chamber so that the pressurized fluid also acts on the anchoring frame. The present invention also provides a sintering press and a method for sintering electronic components on a substrate by using the sintering press.

Description

Technical Field

[0001] The present invention relates to sintering pressure of electronic components on a substrate, and in particular the present invention relates to a pressure group for such pressure. Background Art

[0002] As is known, in some electronic applications, integrated electronic components such as diodes, IGBTs, thermistors, MOSFETs are fixed to a substrate through the interposition of a sintering glue layer.

[0003] In order to sinter each component accurately, the component must be pressed with a force proportional to its projection surface and subjected to a predetermined temperature for an agreed period of time. Since the electronic components to be fixed on the substrate can have dimensions, i.e., projection surface and thickness of the associated housing, that differ greatly from each other, applying pressure on a single pressure member acting on all components of the substrate does not allow the desired strength to be applied on all components.

[0004] Additionally, it is necessary to consider the additional complexity caused by the fact that the glue line may have a thickness that is not exactly the same and uniform for all parts.

[0005] In patent application No. PCT / IB2017 / 058520, in the name of the same applicant and still confidential, a sintering press for sintering electronic components on a support has been proposed, which is able to overcome the drawbacks and limitations of the devices according to the prior art. Such a press is notably provided with a pressing assembly comprising a multi-rod cylinder having a front head and a rear head which together define a compression chamber.

[0006] In the front head, parallel and independent pressure rods are slidably supported. Each pressure rod is coaxial with the corresponding electronic component to be sintered and has a push cross section proportional to the force to be applied to the corresponding electronic component. The area of ​​each electronic component to be sintered and the area for predetermining the pressure are known.

[0007] A sealing membrane extends in the compression chamber, the sealing membrane fluid-tightly dividing the compression chamber into a rear chamber and a front chamber. The rear chamber is in fluid communication with an inlet channel for fluid under pressure to obtain the sintering pressure. The rear ends of the pressure rods protrude into the front chamber. The sealing membrane is placed in contact with the rear ends of the pressure rods so that when the rear ends are pressurized to the sintering pressure, the sealing membrane transmits the sintering pressure to each pressure rod by deforming against the rear ends.

[0008] Such a pressure allows exerting a thrust on the electronic component to be sintered that is proportional to its surface, thanks to the use of a pressure rod for each component, the cross section of which is selected according to the surface to be pressed.

[0009] The sealing membrane formed by the flat gasket actually performs two functions: one is a sealing function for all the pressure rods; and the other is a piston function acting on all the pressure rods, deforming itself in order to adapt to their dimensions.

[0010] The sealing membrane is held circumferentially between the front and rear heads of the multi-rod cylinder. Thus, the flat gasket deforms when subjected to the action of fluid under pressure, but does not translate axially relative to the compression chamber.

[0011] However, it has been found that, over time, due to the high pressures to which the flat washers are subjected in the non-retaining center region between the two heads of the multi-rod cylinder, which can even reach several hundred bars, the flat washers tend to lose their original elasticity or even become destroyed or worn. After a certain number of pressurizing cycles, the flat washers must therefore be replaced. Summary of the invention

[0012] The object of the present invention is to propose a pressure-exerting assembly of the above-mentioned type, which however is able to overcome the above-mentioned drawbacks associated with flat washers.

[0013] The objects are achieved by a press component and a sintering method according to embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features and advantages of the pressure assembly according to the invention may be made more apparent from the following description of a preferred embodiment of the invention, provided purely by way of non-limiting example, with reference to the accompanying drawings, in which:

[0015] - Figure 1 is a schematic plan view of a sintered island using sintering pressure;

[0016] - Figure 2 is a front view of the press;

[0017] - Figure 3 is an axial cross-sectional view of a pressing assembly of a pressing machine closed on a substrate support unit;

[0018] - Figure 4 is an axial cross-sectional view of only the substrate support unit of the press;

[0019] - Figure 5 is a top perspective view of the front head of the multi-rod cylinder of the pressure assembly without the actuating flat washer and the associated frame for anchoring it to the front head;

[0020] - Figure 5a is a view similar to the previous one, with the flat actuating washer positioned on the front head;

[0021] - Figure 5b is a perspective view similar to the previous one, with the anchor frame blocking the actuation with a flat washer to the head;

[0022] - Figure 5c is a perspective view of an assembled multi-rod cylinder, with the rear end portion shown as transparent;

[0023] - Figure 6 is an axial cross-section of only the pressing component of the press;

[0024] - Figure 7 is an enlarged schematic diagram of a portion of a pressure assembly and a substrate support unit, particularly showing an unpressurized compression chamber and some pressure posts in contact with corresponding electronic components of a substrate and a heated pressure member;

[0025] - Figure 7a is a view similar to the previous one, but with a pressurized compression chamber; and

[0026] - Figure 8 is a schematic perspective view of some pressure rods and heated pressure members in contact with electronic components of a substrate. DETAILED DESCRIPTION

[0027] With reference to the drawings, a sintering island will be described below, using a press machine 1 having a press assembly according to the present invention to perform sintering of an electronic component 10 on a substrate 12 .

[0028] The substrates 12 arrive at the sintering press 1 and are received in a tray 2 which is suitable for receiving six substrates 12 , for example.

[0029] The substrate 12 is positioned in a corresponding seat formed in the tray 2, and the seat is adapted to support the substrate 12 on a suitable protrusion.

[0030] The substrate 12 carries the electronic components 10 (eg IGBT, diode, thermistor, MOSFET) to be sintered positioned on a sintering paste layer. The electronic components 10 must be treated at a predetermined surface pressure, eg 30 MPa, at a predetermined temperature, eg 260° C., for 180÷300 seconds.

[0031] The tray 2 with the green substrate 12 must be held steadily at a moderate speed without vibration so as not to change the position of the electronic component 10 .

[0032] Considering that the electronic components 10 have thicknesses that vary according to type, the components must be pressed with a force proportional to their protruding surfaces.

[0033] Furthermore, any non-parallelism of the substrate-glue-electronic component assembly, for example of 1 μm to 10 mm, must be compensated.

[0034] like Figure 1 As shown in FIG. 1 , in one embodiment, the sintering island comprises at least one, preferably two, preheating stations 3 for preheating the tray 2 to 150°C, and at least one, preferably three, cooling stations 4 for cooling the tray 2 to 50°C.

[0035] In one embodiment, the sintering island comprises an anthropomorphic robot 5, such as a 10 kg 6-axis anthropomorphic robot provided with a six-jaw self-centering gripper.

[0036] The robot 5 manipulates the pallet 2 between:

[0037] - between the inlet conveyor 6 and the readers of the two preheating stations 3;

[0038] - between the two preheating stations 3 and the sintering press 1;

[0039] - Between the sintering press 1 and the three cooling stations 4;

[0040] - Between the three cooling stations 4 and the outlet conveyor 7 .

[0041] The two preheating stations 3 are provided to raise the temperature of the respective substrates 12 to a temperature of 150°C.

[0042] For example, the two preheating stations 3 are heated by an electric cartridge equipped with a PID and PWM thermal resistor PT100 control.

[0043] Overall Figure 2 The sintering press 1 shown in FIG. 1 comprises a vertically extending frame 8 which supports a press assembly 14 at the top and a support unit 60 at the bottom for at least one substrate 12 , preferably six substrates in the embodiment shown.

[0044] The frame 8 is provided with longitudinal guides 9 along which the support unit 60 slides, which is operated by a hydraulic or electric actuator 80 .

[0045] In one embodiment, the support unit 60 performs a 200 mm stroke with a uniform acceleration and deceleration motion.

[0046] In particular, the upper position of the support unit 60 is absolutely irreversible and is dimensioned to resist forces of up to 250 KN without movement.

[0047] In one embodiment, a 200 mm stroke is implemented in 3 seconds with a 1 Kw brushless motor 80 and can be implemented in a light touch manner at reduced speeds for molding changes and maintaining functions.

[0048] In one embodiment, the frame 8 also supports a motorized winder 90 and unwinder 92, for example with brushless motors, for replacing a protective film 52, for example PTFE, inserted between the substrate 12 and the pressure assembly 14 during sintering.

[0049] In one embodiment, the protective film 52 is supported by a peripheral frame 50. In one embodiment, the peripheral frame 50 also supports a suction / blowing device directed toward the protective film 52.

[0050] Furthermore, the press 1 is provided with a vacuum pump—not shown—for sucking the air between the PTFE membrane and the press assembly 14 .

[0051] In one embodiment, the press 1 is also provided with a purge ionization device - not shown - to remove any electrostatic charge in the sintering area.

[0052] In one embodiment, the frame 8 also supports horizontal sliding guides that can be inserted and removed with right and left hand handles 94 for facilitating replacement of the support unit 60 .

[0053] Especially in Figure 3 and Figure 4 In the embodiment shown in FIG. 1 , the support unit 60 comprises a fixed reaction block 62 in which six deformation cylinders 68 are accommodated, provided with corresponding deformation sensors 70 capable of operating at 350° C.

[0054] The support unit 60 further includes a heating block 64 in which an equipped heating resistor 641 is accommodated.

[0055] The support unit further comprises six movable reaction blocks 66 , each of which is provided with a corresponding temperature sensor 662 .

[0056] The pressure applying assembly 14 includes a multi-rod cylinder 20 having a front head 22 and a rear head 24 , which together define a compression chamber 26 .

[0057] Between the front head 22 and the rear head 24, an annular sealing element 25 positioned around a compression chamber 26 is interposed.

[0058] For example, the annular sealing element 25 is placed in a corresponding seat 25' formed between a flat portion of the rear end surface 22' of the front head 22 and a flat portion of the front end surface 24' of the rear head 24, such flat portions facing and parallel to each other.

[0059] The annular sealing element 25 thus performs the function of preventing the fluid under pressure present in the compression chamber 26 from escaping between the two side-by-side heads 22 , 24 .

[0060] The annular sealing element 25 is constituted by an O-ring, for example.

[0061] In the rear head 24 , an inlet passage 32 is made to introduce pressurized fluid into the compression chamber 26 .

[0062] In the front head 22, pressure applying rods 28 that are parallel to each other and independent of each other are slidably supported. The rear end portions 28' of such pressure applying rods 28 protrude into the compression chamber 26.

[0063] In the compression chamber 26 , an actuating flat washer 30 extends on the rear end 28 ′ of the pressure rod 30 , so that when the compression chamber 26 is pressurized, the actuating flat washer 30 acts on this rear end 28 ′ to transfer the pressure in the compression chamber to each individual pressure rod 28 .

[0064] For example, each rear end portion 28 ′ of the pressure rod 28 ends in a flat surface onto which the flat washer 30 is pressed.

[0065] According to an aspect of the invention, the flat actuation washer 30 is fixed to the front head 22 by means of an anchoring frame 34 which engages a peripheral portion 30 ′ of the flat actuation washer 30 .

[0066] In other words, the peripheral portion 30 ′ of the flat gasket 30 is at least partially inserted between the base or front surface of the front head 22 and the anchor frame 34 .

[0067] The anchor frame 34 is completely housed in the compression chamber 26 , so that the pressurized fluid introduced into the compression chamber 26 acts not only on the flat gasket 30 but also on the anchor frame 34 .

[0068] As mentioned, the flat gasket 30 held in place by the anchor frame 34 performs the dual role of a sealing gasket and actuating the membrane onto the pressure rod 28 .

[0069] In particular, when the compression chamber 26 is pressurized, the pressure of the fluid is not only applied to the central portion of the flat gasket, but also to the peripheral portion 30' through the anchor frame 34. Therefore, the flat gasket 30 is subjected to uniform stress over its entire surface and is compressed at the same time. This avoids undesirable deformation of the gasket, thereby greatly increasing the life of the gasket.

[0070] In more detail, the rear head portion 24 forms a bottom wall 27 for the compression chamber 26; the anchor frame 34 has a rear surface 34b facing the bottom wall 27 and separated from the bottom wall.

[0071] In one embodiment, the compression chamber 26 is delimited in the radial direction by a side wall 29 ; the anchor frame 34 has a side surface 34 c facing the side wall 29 and separated from the side wall.

[0072] In this manner, the pressurized fluid acts on all exposed sides of the anchor frame 34 to prevent it from moving or deforming.

[0073] In one embodiment, the anchor frame 34 is screwed to the front head 22 by anchor screws 35 .

[0074] However, it should be emphasized that the fixing of the anchor frame 34 to the front head 22, for example by means of the anchor screws 35, does not have the function of retaining the flat gasket 30 when the compression chamber 26 is pressurized, but only retains the flat gasket in the correct position when the compression chamber is not pressurized. In fact, in the presence of a pressurized fluid in the compression chamber 26, it is the pressure exerted by the fluid that allows the flat gasket 30 to be locked in place.

[0075] In one embodiment, a flat gasket 30 divides the compression chamber 26 into a front portion 26 ′ and a rear portion 26 ″ into which the rear end 28 ′ of the pressure-applying rod 28 protrudes, and the rear portion is in fluid communication with an inlet conduit 32 .

[0076] In one embodiment, the front portion 26 ′ of the compression chamber 26 is formed in the lower portion 22 a of the rear end surface 22 ′ of the front head 22 .

[0077] In the absence of pressure in the compression chamber 26, the flat gasket 30 is in a substantially flat resting configuration and is positioned to slightly contact the rear end 28' ( Figure 7 ).

[0078] When the rear portion 26" is pressed at the sintering pressure, the flat washer 30 is deformed to abut against the rear end portion 28' of the pressure rod 28 to transmit the sintering pressure to each pressure rod 28 ( Figure 7a ).

[0079] More precisely, the projection of the rear end 28' of the pressure rod 28 relative to the lower portion 22a of the front head 22, and therefore the distance between the flat washer 30 and said lower portion 22a, is chosen so that when the rear portion 26" is pressed at the sintering pressure and the flat washer 30 is deformed, the washer abuts not only the rear end 28' of the pressure rod 28, but also the lower portion 22a of the front head 22, in particular as Figure 7a shown.

[0080] Due to this configuration of the compression chamber 26, the flat washers 30 act as if the control fluid acts directly on the respective rear end 28' of the pressure rod 28 at the desired sintering pressure. In other words, the flat washers 30 simulate the behavior of a plurality of independent cylinder-piston systems.

[0081] Returning now to the pressure rods 28, each of them is coaxial and centroidal with the corresponding electronic component 10 to be sintered, and has a push cross section proportional to the force applied to the corresponding electronic component 10, each of which has a known area and a predetermined sintering pressure.

[0082] The term “center of gravity” means that each pressure applying rod 28 has a rod axis that coincides with the center of gravity of the corresponding electronic component 10 .

[0083] In one embodiment, the press assembly 14 further includes a heating block 40 that is integral with the multi-rod cylinder 20 and slidably supports heated press members 42. Each heated press member 42 can be actuated by a corresponding press rod 28 to act on a corresponding electronic component 10 to be sintered.

[0084] Figure 8 The perspective view in FIG. 4 shows four pressure rods 28 of different cross-sections, which act on corresponding heated pressure members 42 also of different cross-sections.

[0085] The heating and pressure applying members 42 are shown adjacent to the respective electronic components 10 , resting on the substrate 12 supported by the support unit 60 .

[0086] In one embodiment, the pressure rod 28 has a rounded front end 28' that contacts the flat surface 42' of the heated pressure member 42. For example, the front end 28' of the pressure rod 28 is spherically rounded to concentrate the compressive force on the center of gravity of the corresponding electronic component to be sintered and simultaneously generate thermal damage between the pressure rod 28 and the pressure member 42. In this way, the heated pressure member 42 can be easily adapted to the surface of the electronic component to be pressed and heated.

[0087] In one embodiment, the heating and pressing member 42 is in the form of a rod having a cross section substantially corresponding to or larger than the area of ​​the housing of the corresponding electronic component 10 to be sintered.

[0088] In one embodiment, the multi-rod cylinder 20 is capable of applying a force proportional to the cross-section of the single pressure-applying rod 28 to generate a pressure corresponding to 30 MPa on all electronic components 10 .

[0089] In one embodiment, four pressure rods and members for IGBTs, one pressure rod and member for diodes, one pressure rod and member for thermistors, and one pressure rod and member for MOSFETs are provided for each substrate 12, for a total of 48 pressure members and associated pressure rods, all independent and having different cross-sections proportional to the thrust to be generated.

[0090] In one embodiment, the compression chamber 26 may be pressurized to 35 MPa (350 bar).

[0091] As described above, the heating pressure applying member 42 has the task of transmitting the compressive force and heat to the electronic component 10 to be sintered on the substrate 12 .

[0092] In one embodiment, the heating block 40 is provided with an equipment resistor 44 and a temperature sensor 45 .

[0093] The pressing member 42 is barycentrically pushed relative to the corresponding electronic component 10 to be sintered on the substrate, and is slid into the heating block 40 with a suitable clearance to allow their parallel adjustment in the range of 1 μm to 10 mm.

[0094] It should be noted that if the thicknesses of the electronic components 10 vary, they do not cause changes in the sintering pressure of other components.

[0095] It should be noted that, as described above, although the axis of each pressure rod 28 must coincide with the center of gravity of the corresponding electronic component 10, the shape, cross-section and position of the pressure member 42 relative to the corresponding pressure rod 28 can be selected based on the shape of the electronic component 10 and / or its position on the substrate.

[0096] For example, the pressure applying member 28 may be selected in order to sinter the electronic components 10 in a reliable and precise manner, also when the electronic components are very close to each other or have non-rectangular or very different sizes.

[0097] It should also be noted that the implementation of each pressure member of the pressure assembly 14 in two separate parts, namely the pressure rod 28 and the pressure member 42 placed in contact via the generally spherical surface 28″, allows thermal disruption between the multi-rod cylinder 20 and the heating block 40 to be obtained. For example, when the heating block 40 is operated at a temperature that can reach 300° C., the multi-rod cylinder 20 connected to the cooling circuit can be kept below 100° C.

[0098] The multi-rod cylinder 20 thus cooled is subject to less wear than the heating block 40 and needs to be replaced much less frequently.

[0099] In a general embodiment, a method for sintering electronic components on a substrate using the above-described press comprises the following steps:

[0100] - establishing a constant sintering pressure to be applied to all electronic components to be sintered;

[0101] - equipping the pressure-applying assembly with a pressure-applying rod having a corresponding push cross-section according to the pressure-applying surface of the corresponding electronic component;

[0102] - placing the substrate with the sintering paste and the electronic components to be sintered in a press so that the electronic components are in contact with the end pins of the press member;

[0103] - heating the pressure member to a predetermined sintering temperature;

[0104] - pressurizing the compression chamber to a predetermined sintering pressure;

[0105] - Maintaining the sintering pressure and sintering temperature for a predetermined sintering time;

[0106] -Removing the substrate from the sintering press.

[0107] In one embodiment, a protective film is attached to an end portion of the pressure member before positioning the substrate.

[0108] In one embodiment, during the step of pressurizing the compression chamber to a predetermined sintering pressure, the sealing film is deformed so that the sealing film contacts both the rear end of the pressure rod and the substantially flat bottom wall of the front portion of the compression chamber.

[0109] The sintering cycle will now be described in more detail.

[0110] While the sintering step is taking place, a robot 5 manages the trays 2 arriving at the inlet conveyor 6 , picking them up and placing them in one of the two free preheating stations 3 .

[0111] During the sintering step, the robot 5 also takes care of the trays 2 resting in the three cooling stations 4. At the end of a programmed cooling cycle, the robot picks up the tray from the corresponding cooling station and deposits it in the exit conveyor 7.

[0112] At the end of the sintering step, the following steps are performed in sequence.

[0113] The multi-rod cylinder 20 is depressurized from about 35 MPa to about 0.5 MPa. In this way, the heating and pressing member 42 functions as a blank holder having a predetermined force.

[0114] The decompression of the multi-rod cylinder is controlled by a pressure sensor housed in a reaction block of the support unit 60 .

[0115] The support unit is lowered from the forward pressing position in a uniformly accelerated and decelerated motion, thereby completing a stroke of 200 mm.

[0116] The peripheral frame 50 is lowered by 10 mm, thereby releasing the protective film 52 .

[0117] Then, the vacuum pump of the pressurizing group 14 is lightly pressurized to separate the film from the pressurizing member.

[0118] The unwinding reel and the winding reel of the protective film are actuated so as to position a portion of the integral film under the pressure member of the pressure assembly. Preferably, this operation must be performed while the tray containing the newly sintered substrate is still present. This prevents glue or film residues from falling onto the support unit 60 or, worse, onto the not yet sintered substrate.

[0119] The robot picks up the pallet from the press and places it in a free station in one of the three cooling stations.

[0120] The robot picks up a tray with substrates to be sintered, which has completed a preheating cycle at 150° C., and then gently places it in the support unit 60 .

[0121] A vacuum is then activated between the pressure-applying assembly 14 and the protective film, causing the film to adhere to the pressure-applying member of the pressure-applying assembly 14 .

[0122] As soon as the robot leaves the collision zone, the support unit 60 rises with a uniform acceleration and deceleration motion. In particular, in one embodiment, during the last 15 mm of travel of the support unit 60 with the tray and the associated substrate, the support unit 60 collides with the peripheral frame 50 of the pressure assembly 14, thereby lifting it. During the last 2 mm of travel of the support unit 60, the substrate centered in the tray housing and resting directly on the respective movable reaction block of the support unit 60 collides with the pressure member covered by the protective film.

[0123] The pressing member 42 , which is slightly pressed in this step, is retracted, thereby serving as a blank holder.

[0124] The support unit 60 reaches the upper end position of the stroke.

[0125] The multi-rod cylinder is pressurized at the programmed pressure.

[0126] The pressurization of the multi-rod cylinders is controlled by corresponding deformation sensors which measure the cumulative compressive force exerted on each base plate by the pressure-applying members.

[0127] In one embodiment, the sintering temperature of the substrate is generated by equipment chuck resistors housed in the lower heating block 64 and the upper heating block 40 .

[0128] In one embodiment, the sintering temperature is independently controlled in the press group and the support unit, for example by appropriately positioned thermal resistors PT100.

[0129] Preferably, the substrate is heated from below by the movable reaction block and from above by the pressure member and the protective film. Due to the different heating conditions, the upper and lower heating temperatures can be differentiated to compensate for the difference in heat transfer to the substrate.

[0130] In one embodiment, the electronic components on the substrate are maintained at a temperature of 260° C. for a programmed time (eg, 300 seconds) and pressurized at 30 MPa to perform sintering of the components on the substrate.

[0131] Once the sintering time has elapsed, the multi-rod cylinder is depressurized and the press is reopened as described above.

[0132] Without departing from the scope of the appended claims, a person skilled in the art may make numerous changes, adjustments, adaptations and substitutions of the embodiments of the press assembly and the sintering press according to the invention with other functionally equivalent elements in order to meet contingent needs. Each feature described as belonging to a possible embodiment can be obtained independently of the other embodiments described.

Claims

1. A press assembly (14) for a sintering press for performing sintering of electronic components (10) on a substrate (12), the press assembly comprising a multi-rod cylinder (20) having a front head (22) and a rear head (24), the front head and the rear head together defining a compression chamber (26), wherein: - between the front head and the rear head, an annular sealing element (25) is inserted, positioned around the compression chamber (26), - an inlet passage (32) is formed in the rear head (24) for introducing pressurized fluid into the compression chamber; - a pressure rod (28) is slidably supported in the front head (22), the pressure rods are parallel to each other and independent, and the rear end of the pressure rod protrudes into the compression chamber (26), - in the compression chamber (26), a sealing film (30) extends over the rear end of the pressure rod, so that when the compression chamber (26) is pressurized, the sealing film (30) acts on the rear end to transmit the pressure in the compression chamber to each individual pressure rod (28), - the sealing membrane (30) is fixed to the front head by means of an anchoring frame (34), the peripheral portion (30') of the sealing membrane (30) being at least partially inserted between the front head (22) and the front surface (34a) of the anchoring frame (34), - The anchor frame (34) is completely housed in the compression chamber so that the pressurized fluid also acts on the anchor frame.

2. The pressure applying assembly according to claim 1, wherein: The compression chamber (26) forms a bottom wall (27) opposite to the sealing membrane (30), and wherein the anchor frame (34) has a rear surface (34b) facing the bottom wall and separated from the bottom wall.

3. The pressure applying assembly according to claim 1 or 2, wherein: The compression chamber (26) is delimited in the radial direction by a side wall (29), and wherein the anchor frame has a side surface (34c) facing the side wall and separated from the side wall.

4. The pressure applying assembly according to claim 1 or 2, wherein: The anchor frame (34) is screwed to the front head (22).

5. The pressure applying assembly according to claim 1 or 2, wherein: The sealing membrane (30) divides the compression chamber into a front portion (26') and a rear portion (26"), wherein the rear end of the pressure-applying rod protrudes into the front portion, and the rear portion is in fluid communication with the inlet channel (32).

6. The pressure applying assembly according to claim 5, wherein: The front part of the compression chamber is obtained in the lower part (22a) of the front head.

7. The pressure-applying assembly according to claim 1 or 2 further includes a heating block (40), which is integrated into the multi-rod cylinder body (20) and slidably supports a heating pressure member (42) in the form of a rod, each heating pressure member (42) having a rear end portion in contact with the front end portion of the corresponding pressure rod (28), so that each heating pressure member (42) can be pressed by the corresponding pressure rod (28) to act on the corresponding electronic component (10) to be sintered, and the heating block (40) is provided with a heating device (44) for heating the heating pressure member (42).

8. The pressure applying assembly according to claim 7, wherein: Each pressure rod (28) terminates in a rounded end (28") which contacts the flat end surface of a corresponding heated pressure member (42).

9. A sintering press comprising a pressing assembly according to claim 7 or 8 and a support unit (60), the support unit facing the pressing assembly (14) and being suitable for supporting at least one substrate (12), at least one of the pressing assembly (14) and the support unit (60) being axially translatable relative to the other between a retracted rest position and an advanced pressing position, wherein The electronic components (10) can be joined by the heating and pressurizing member (42).

10. A method for sintering electronic components on a substrate by means of the sintering press according to claim 9, comprising the steps of: - determining a constant sintering pressure to be applied to all electronic components to be sintered; - equipping the pressure assembly with pressure rods having respective push cross sections proportional to the force to be applied to the respective electronic component, the area of ​​each electronic component to be sintered being known and used for a predetermined constant sintering pressure; - positioning the substrate having the sintered layer and the electronic component to be sintered in the press so that the electronic component is in contact with the front end of the heating and pressing member; - heating the heating and pressing member to a predetermined sintering temperature; - pressurizing the compression chamber to a predetermined sintering pressure; - Maintaining the predetermined sintering pressure and the predetermined sintering temperature for a predetermined sintering time; - Removing the substrate from the sintering press.

11. The method according to claim 10, wherein: The substrate is also heated to a predetermined sintering temperature.

12. The method according to claim 10 or 11, wherein: Prior to the step of positioning the substrate, a protective film is attached to the front end portion of the heating and pressing member.

13. The method according to claim 10 or 11, wherein: The sealing film (30) divides the compression chamber into a front part (26') and a rear part (26"), the rear end of the pressure rod protruding into the front part (26'), the rear part (26") is fluidically connected to the inlet channel (32), and wherein, during the step of pressurizing the compression chamber to a predetermined sintering pressure, the sealing film is deformed so that the sealing film rests on both the rear end of the pressure rod and the flat bottom wall of the front part of the compression chamber.

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