Patent Application
20240038607
This application claims the priority benefit of French Application for Patent No. 2207955, filed on Aug. 1, 2022, the content of which is hereby incorporated by reference in its entirety to the maximum extent allowable by law.
Embodiments and implementations relate to integrated circuit packages, whether they are optical or not, and especially relate to integrated circuit packages equipped with at least one cavity generally for housing one or more electronic components, for example but not limited to, electronic integrated circuit chips, surface-mount components, optical components, etc.
Currently, the cavities provided in integrated circuit packages require one or more ventilation holes in order to ensure reliability of these packages.
Indeed, the absence of a ventilation hole can lead to overpressure and delamination of some materials of the package during the manufacture of the package, leading to operating problems.
But the flow of operations for assembling a package includes, especially, sawing and cleaning operations.
As a result, water can enter the package, leading to pollution of the cavity, degradation of optical performance (in the case of optical packages), condensation, oxidation of components and reliability problems.
There is therefore a need to provide packages having cavities that can be equipped with ventilation holes while limiting ingress of external pollution (water and liquids, particles, etc.) into these cavities as much as possible.
According to one aspect, an integrated circuit package is provided comprising a cavity and at least one through hole, provided in at least one wall of the cavity, said at least one through hole comprising at least one first portion flaring towards the cavity.
As a result, the capillary force becomes negligible due to the flaring effect of the first portion, in relation to the force of gravity, which greatly reduces or even eliminates the risk of external pollution, in particular moisture, penetrating the cavity.
In general, the package may typically comprise a carrier substrate and a device attached to the carrier substrate and delimiting said cavity with the carrier substrate.
This device may be, for example, a cover, an optical sealing means (for example, a glass pane), or even a molded element.
Said wall includes a part of the carrier substrate and a part of the device. And, said at least one through hole may be provided in said part of the carrier substrate and/or said part of the device.
Said at least one first portion flares from a first end to a second end. And, in order to further promote flaring effect to make the capillary force negligible, the cross-section of said at least one first portion at the first end has a largest dimension less than or equal to 35 micrometers.
Said at least one first portion may be frustoconical.
According to one embodiment, said at least one first portion extends over the entire thickness of said at least one wall.
This is, for example, the case for relatively thin carrier substrates.
For relatively thick carrier substrates, said at least one through hole may include at least one second portion opening into said at least one first portion at the end of this first portion having the smallest cross-section.
This second portion may be cylindrical or may flare away from said at least one first portion.
According to one embodiment, said at least one second portion may be frustoconical and said at least one through hole then includes the first portion and the second portion connected by their respective ends having the smallest cross-section.
According to another aspect, a method is provided for making at least one through hole in at least one wall of a cavity of an integrated circuit package, making said at least one through hole comprising making at least one first portion flaring towards the cavity.
According to one implementation wherein the package comprises a carrier substrate and a device attached to the carrier substrate and delimiting said cavity with the carrier substrate, said wall including a part of the carrier substrate and a part of the device, said at least one through hole is made in said part of the carrier substrate and/or in said part of the device.
According to one implementation, said at least one first portion is made so that it flares from a first end to a second end, the cross-section of said at least one first portion at the first end having a largest dimension less than or equal to 35 micrometeres.
According to one implementation, said at least one first portion is made with a frustoconical shape.
According to one implementation, said at least one first portion is made so that it extends over the entire thickness of said at least one wall.
Making said at least one first portion advantageously comprises laser drilling.
Indeed, laser drilling naturally provides a flared shape to the port drilled.
According to one implementation, making said at least one through hole includes making at least one second portion opening into said at least one first portion at its end having the smallest cross-section.
Said at least one second portion may be made so that it has a cylindrical shape.
In this case, making said at least one second portion advantageously comprises mechanical drilling.
Said at least one second portion may also be made so that it flares away from said at least one first portion.
In this case, said at least one second portion is advantageously performed by means of laser drilling.
According to one implementation, making said at least one through hole comprises making said at least one second portion having a frustoconical shape, and making the first portion and the second portion so that they are connected by their respective ends having the smallest cross-section.
Further advantages and characteristics of the invention will become apparent upon examining the detailed description of embodiments and implementations, which are by no means limiting, and the appended drawings in which:
In
This integrated circuit package comprises a carrier substrate 1, for example a conventional multilayer carrier substrate, including a first face F1, typically an upper face, and a second face F2, typically a lower face.
The second face F2 is here equipped with an array of solder balls 8 for being soldered to a printed circuit board.
A cover 2 is attached to the first face F1 of the carrier substrate 1 by means of a conventional attachment means 3 such as an adhesive material.
A part of the carrier substrate 1 and a part of the cover 2 delimit a cavity 4 in which, an electronic integrated circuit chip 50 and an electronic component 51, for example a surface-mount component, are housed, in this exemplary embodiment.
The electronic chip 50 rests on the first face F1 of the substrate via connection balls or bumps 500.
An underfill material 600 is disposed between the electronic chip 50 and the first face F1 of the substrate.
In this example, a thermal interface material 7 is disposed between the upper face of the chip 50 and the cover 2 so as to promote thermal dissipation of the package.
In this exemplary embodiment, a through hole 9 is provided extending in and completely though the entire thickness of a part of the carrier substrate and flares (for example, increases in size) towards the cavity 4.
As a result, the risk of moisture H penetrating the cavity is greatly reduced or eliminated.
As illustrated in more detail in
The first portion 91 may be frustoconical.
The cross-section S1 of the first portion 91 at the first end 911 is then, for example, a circular cross-section, the largest dimension, or diameter, d1 of which is advantageously less than or equal to 35 microns.
The second end 912 of the first portion 91 has a cross-section S2, also circular, the largest dimension, or diameter, d2 of which may be, for example, in the order of 100 microns.
As a result, the capillary force becomes negligible in relation to, for example, the force of gravity, due to the conical effect and the opening size of the first end 911.
Such an embodiment, providing a first portion passing through the entire thickness of the carrier substrate is typically possible for relatively thin carrier substrates, that is having for example a thickness less than or equal to 1000 μm.
This portion 91 can advantageously be made by laser drilling P1 which naturally provides a flared shape to the port drilled.
In the case of a thicker carrier substrate, having for example a thickness greater than or equal to 4000 μm, a through hole 9 can be provided, as very schematically illustrated in
In
In this embodiment, any moisture that may have penetrated the second portion 92 gets stuck at the first portion 91.
While the first portion 91 is advantageously made by laser drilling P1, the second portion 92 can be made by mechanical drilling P2.
In one embodiment of
More precisely, the second portion 92 has a first end 921 which is coincident with the first end 911 of the first portion.
The second portion 92 has a second end 922 opening onto the second face F2 of the carrier substrate.
The cross-section S2 of this second end 922 is larger than the cross-section Si of the first end 921.
The two portions 91 and 92 may thus be frustoconical, the two frustoconical parts 91 and 92 being mutually connected at their respective ends 911 and 921 having the smallest cross-section S1.
In this embodiment, the two frustoconical portions 91 and 92 can be advantageously made by laser drilling P1.
Here again, any moisture H which would have penetrated the second portion 92 will be stopped from penetrating through the first frustoconical portion 91.
The invention is not limited to the embodiments and implementations described here, but encompasses all alternatives.
Thus, the invention can be applied to all types of packages, in particular an optical package BT2 such as that schematically illustrated in
This optical package BT2 includes a carrier substrate 1 equipped on its second face F2 with an array of connection balls 8. An optical sealing element 10, for example a glass pane, is attached to the carrier substrate 1 by means of a conventional attachment means 11 such as an adhesive material and defines, together with the carrier substrate, the cavity 4 which houses in this example an optical component 50.
Here again, a through hole 9 flaring towards the cavity 4 from the second face F2 of the carrier substrate limits or even eliminates the risk of moisture H penetrating the cavity 4.
Whereas in the embodiments of
In the present case, this device is the cover 2 in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2207955 | Aug 2022 | FR | national |
