Flexstar-Auto-2-F-L
Fully automatic 2-strip multiplunger system designed for QFN-MAP and QFN-Punch type lead frame packages. Equipped with our patented Adhesive Film Technology and lamination technology to minimize the bleed level, optimize throughput and cut film costs. For QFN-MAP devices, molding costs can be cut by as much as 60 % compared to pre-tape technology.
60 % lower cost of ownership
Adhesive Film Technology (AFT) is a cost-effective and reliable process for QFN package encapsulation.
Adhesive Polyimide film (pre-tape) is often used for the encapsulation of QFN packages. This film is intended to protect leads and die pads on lead frame strips against contamination with epoxy compound bleed. Polyimide film is pre-attached to the lead frame before the assembly process. It is a very expensive material and has a different CTE compared to lead frame material. The adhesive bond between the film and lead frame can be easily disturbed because it is subjected to several thermal cycles of the die, wire bonding and molding processes. Additional pre-heating on the mold surface is required to limit the influence of different CTEs, which considerably lengthens the mold cycle time. Boschman Technologies’ AFT molding process offers faster process cycle times and uses a much cheaper adhesive film that significantly limits the risk of compound bleed by excluding CTE effects. The combination of a cheaper film, higher yields and higher uph makes the AFT process a very attractive option for QFN molding. It can cut cost of ownership by a whopping 60 % compared with the process that uses pre-tape. Boschman Technologies has developed and patented a new method that completely eliminates the drawbacks of the pre-tape process while using a much cheaper adhesive film. This method consists of laminating the film to the lead frame in the mold after the die and wire bonding process. The lead frame and film are individually pre-heated to molding temperature. The molding system has an automatic lamination tool that laminates film and lead frame together at molding temperature at a programmable lamination force, while both lead frame and film are in the mold. The hot lead frame is positioned on the hot film and they laminated together prior to mold closure.
The molding system is equipped with a fully integrated film handler that can handle film on rolls. Fresh film is used for each molding shot. The layer of film will automatically be removed from the lead frame at the same time the molded shot is offloaded from the mold, meaning that no additional time is required for film removal. This method of laminating and removing the film at the same temperature eliminates the influence of different CTEs and contributes to much better bleed control, shortens the molding cycle and boosts uph.
The diagram below shows that the AFT process is on average 27 % faster than the pre-tape process, as measured in 5 molding systems, all at different assembly sites.
Film used in the AFT process is far more economical than the Polyimide used in the pre-tape method, because the film is made of economical polyester. An added benefit of Boschman Technologies' AFT process is that no taping or de-taping equipment is required. Those assembly sites that apply and remove their own tape, always used to have to purchase special taping and de-taping machines. And lead frame users always used to have to pay lead frame suppliers extra for film application. Pre-tape film costs are usually hidden in the total lead frame costs, but will on average amount to about US$ 0.90 per lead frame in extra costs. The logical consequence of us having integrated all process steps into the molding system is a slightly higher system price compared to a conventional molding system without automatic film handling, taping and de-taping. However, the cost savings and return of investment (ROI) offered by our total molding system more than compensate for that.
Universal use
Flexstar 2-strip and 4-strip systems can also be used for pre-tape QFN lead frames. These systems are very easy to convert. They can also handle substrate-based packages such as BGA, BOC and BGA-MAP, including applications (such as flip-chip, multi chip array and stacked die). Our Seal Film Technology is a further option for ultra-thin substrate-based packages or one-sided exposed die packages.
