The ultimate goal of this work is to find the optimal condition for the even distribution of two-phase mixture at header-channel junctions simulating the corresponding parts of compact heat exchangers. The cross section of the header and the channels were 14 mm $ imes$ 14 mm and 12 mm $ imes$ 1.6 mm, respectively. Two different distances between channels (10 and 21.6 mm) and four different intrusion depths (0, 1.75, 3.5 and 7 mm) beyond the inner wall of the header were tested for the mass flux and the mass quality ranges of 70-165 $kg/m^2s$ and 0.3-0.7, respectively. Air and water were used as the test fluids. The flow distribution pattern was relatively insensitive to the channel distance because the flow configuration inside the header remained almost unchanged. On the other hand, the distribution pattern was changed drastically with the intrusion depth of the channels. The optimum intrusion depth for even flow distribution was identified to be 1/8 of the hydraulic diameter of the header cross-section for the experimental conditions tested in the present work.