High frequency measurements and simulations on wire-bonded modules on the sequential build-up boards (SBU´s)

This paper presents the results from high-frequency measurements and simulations on sequential build-up boards (SBU´s). A high-frequency test pattern was designed in order to investigate the high-frequency properties of SBU´s. The SBU boards were supplied by four different manufacturers. The test boards contained patterns for crosstalk, impedance matching, stray capacitance, and wire-bonding. The test boards consisted of doublesided FR-4 core with two built-up layers on each side. However, the high-frequency test board was only on one side of the core. The test patterns were located in layer five and layer six. Two different line spacings between signal track and victim track, 50 and 100 μm, were considered. The S-parameters were measured on a network analyzer in the frequency range 45 MHz-10 GHz. In the time domain experiment, the near-end and the far-end response in the victim track was measured. All the simulations were carried out, using the simulation programs P-Spice, HP MDS, and a two-dimensional (2-D) finite difference program. Impedance measurements and simulations were performed in layer five and six with conductor widths corresponding to characteristic impedances of 50 and 55 Ω. The line widths ranged from 40 to 65 μm in layer five and 150 to 200 μm in layer six. Reference tracks were designed in order to estimate conductor and dielectric losses