Synthetic resin fusion body

A synthetic resin weld body, comprising:

• a first member made of synthetic resin which forms a plurality of first passage parts including a plurality of bores;
• and
• a second member made of synthetic resin which forms a plurality of second passage parts;
• wherein said first member is configured to connect to said second member;
• wherein each of said first passage parts includes a top end connecting face formed around a respective one of said bores and having a first end and a second end, first and second mount connecting faces rising from said first and second ends, respectively, of the top end connecting face, and first and second ridge lines disposed on each of said first passage parts adjacent said first and second mount connecting faces, respectively;
• wherein, for each of said first passage parts, a first rising boundary line is defined between said first end of said top end connecting face and said first mount connecting face, and a second rising boundary line is defined between said second end of said top end connecting face and said second mount connecting face;
• wherein all of said first and second rising boundary lines are substantially parallel to one another;
• wherein a plurality of passages are formed by connecting said first passage parts and said second passage parts, respectively, when said first member and said second member are connected and vibration-welded, the vibrations in the vibration welding being applied in a direction substantially parallel to the rising boundary lines;
• wherein at least one of the plurality of passages extends in an orthogonal direction that is substantially orthogonal to the direction in which the rising boundary lines extend and at least another of the plurality of passages extends in a direction different from the orthogonal direction in which the at least one of said plurality of passages extends;
• and
• wherein each said rising boundary line is disposed at or within a predetermined distance of a contact point between the respective mount connecting face where the respective ridge line is tangential to a respective bore and the respective end of the top end connecting face at the inner edge of said top end connecting face at the respective bore.