• Packaging
  • Vacuum soldering
  • Advanced Packaging
• Micro and Nanotechnology

The semiconductor industry has responded to increasing demand for miniaturization, portability, speed and performance with the development of so-called advanced packaging technologies, which deliver cost reductions, shorter market cycles, greater mobility and improved miniaturization.
centrotherm thermal solutions offers the following advanced packaging technologies:

Die attach

Die attach technology provides a high-quality connection with lead-free, eutectic and highly leaded solder alloys using thermal contacting. In this process, the substrate is usually soldered onto in just one step. centrotherm offers vacuum soldering systems with various activation processes (flux, formic acid HCOOH, forming gas N₂/H₂ 95/5, hydrogen H₂ 100). The systems guarantee voidless and ultraclean solder joints and work without flux when an appropriate activation type is selected (fluxless).

Wafer bumping with solder alloys

Lead-free, eutectic and highly leaded solder alloys are used with wafer bumping. centrotherm thermal solutions’ vacuum soldering technology provides advanced solutions for wet chemical activation with formic acid (HCOOH) or dry chemical activation with forming gas (N₂/H₂ 95/5) and/or hydrogen (H₂ 100). The forming gas and hydrogen solutions are combined with plasma excitation, previously used in photoresist ashing with oxygen plasma. The hydrogen content, which is generally unresponsive to reaction, is used for the reduction of oxide layers. All activation and plasma processes are carried out together in a vacuum soldering processing chamber.

Hermetic sealing with solder alloys

Hermetic sealing with solder alloys can be carried out in a defined atmosphere and/or under defined pressure. Micro-Electro-Mechanical Systems (MEMS), such as high-resolution acceleration sensors or high-speed actuators, can only operate under high-vacuum (10^-5 mbar) or atmospheric (helium, forming gas, hydrogen, argon, etc.) conditions. centrotherm provides vacuum soldering systems for voidless sealing of the MEMS module.

Plasma activation

Plasma activation is required for chip and module packaging to increase the ultra-cleanness of the bond pads, and consequently the quality of the solder joints. H⁺ ions are used for the reduction of oxide layers on substrates, solder alloys and chip backside metallization. Plasma-based processes have proven successful for the activation of H⁺ ions from molecular hydrogen. centrotherm has therefore integrated plasma activation into the vacuum soldering process and supplies systems with a plasma option which are ideal as activation/cleaning systems.

Flip-chip packaging

Flip chips from wafer level packages or chip-size packages are assembled “flipped over” so that the entire chip surface is available for contacting. Whereas electrical contacting is generally produced using bumps, underfill is usually opted for in mechanical contacting.  centrotherm’s vacuum soldering processes are ideal for this purpose and enable voidless remelting with a very small fine pitch and without flux residue, which eliminates the need for an expensive cleaning process. The additional plasma activation also has a positive impact on the flow behavior and the structure of the underfill material.

Wafer level packaging & chip size packaging

Flip-chip technology produces a package size that corresponds to the size of the chip (wafer level package), or is close to the chip size (chip size package). In chip size packaging, however, the package size cannot exceed 1.2 times the chip size.
centrotherm vacuum soldering processes are ideally suited to the soldering of bumps and enable voidless soldering and very small fine pitches. Thanks to fluxless soldering, the need for expensive subsequent removal of the flux residue is eliminated. The additional plasma activation is favorable to the underfill process (flow behavior and structuring of the underfill material is significantly improved).

System-in-package

In system-in-packages (SiP) and multi-chip modules, there are one or more chips in a module or on a substrate. SiP can be inserted onto the substrate vertically (3D Interconnect) or horizontally (die attach). Soldering with bumps is generally used for contacting where the chips are used as flip-chips, wafer-level packages or as chip-size packages. On account of voidless solder connections, and fluxless, ultraclean soldering, centrotherm vacuum soldering technology is ideal for system-in-package applications.

3D Interconnect

3D Interconnect enables the assembly of vertical system-in-packages in connection with through-silicon via technology. Generally, 3D Interconnect solder bonding involves solder deposits or bumps.
centrotherm supplies solutions for the easy implementation of voidless and ultraclean solder connections. The vacuum soldering systems do not require flux, which meets a key requirement of system-in-packages, as they usually cannot be cleaned.