The concept of interleaved composites was introduced by American Cyanamid [1]. In this concept a standard prepreg containing 60 vol% fibers is used as a basis, and a discrete layer of very high toughness, very high shear strain resin is added to it. The interleaved system exhibits superior behavior in compression after impact (CAI) compared to the non-interleaved material using the same basic matrix resin. The major disadvantage of this system is a weight penalty. The tough layers usually have lower stiffness and strength which proportionally reduce the stiffness and strength of the laminate, requiring additional graphite piles to maintain design properties [2]. Inspired by the natural laminates e.g., shells and woods with typically periodic layered structures, we arrived at a concept [3] for graphite/thermosetting laminates by periodically interspersing solid thermoplastic thin films of about a few tens of microns between each graphite ply. An interaction between them occurs at elevated temperatures typically during the curing reaction, resulting in a granular phase-inversion structure. Thus, the procedure can be regarded as ex-situ compared to the traditional in-situ phase separation. For the 16-ply exsitu graphite/epoxy laminates with 15 tough interleaves [4], the CAI value of 345 MPa was far higher than the 267 MPa of the in-situ toughened specimen, though their basic compositions were exactly same. It was also proven that the in-plane mechanical properties of the ex-situ laminates were mostly retained and the material exhibited a rather balanced specific profile of strength, stiffness, impact resistance and processing abilities [5]. The ex-situ concept would be an all-purpose concept for toughening any laminates regardless of the chemistry of matrix resins. A comparison between the interleaved system with only one discrete tough, thick layer and the periodically interleaved ex-situ system leads to the question of how the interleaf sequence affects the impact damage in graphite/epoxy laminates. The base matrix composition for this study was a combination of standard diglycidal ether of bisphenolA epoxy (DGEBA, E-54, Wuxi Resin Factory) and tetraglycidyl methylene dianiline epoxy (TGMDA,