Synthetic resin joined body and method of manufacturing the same

A synthetic resin joined body comprising:

• a first synthetic resin part;
• a second synthetic resin part which comes in contact with the first synthetic resin part;
• a flow passage which is formed between the first synthetic resin part and the second synthetic resin part and through which fluid flows;
• a sealing portion which is formed by welding the first synthetic resin part and the second synthetic resin part to each other on an outer side of the flow passage to seal a periphery of the flow passage;
• and
• a joint portion for joining the first synthetic resin part and the second synthetic resin part to each other.

A method of manufacturing a synthetic resin joined body comprising:

• a transmission-side synthetic resin part preparing step of preparing a laser light transmissive transmission-side synthetic resin part including a first flow passage forming portion for forming one part of a flow passage through which fluid flows;
• an absorption-side synthetic resin part preparing step of preparing a laser light absorbing absorption-side synthetic resin part including a second flow passage forming portion for forming the other part of the flow passage and a welding portion which is formed into a protruding shape at a periphery of the second flow passage forming portion;
• a disposing step of disposing the transmission-side synthetic resin part and the absorption-side synthetic resin part so that the first flow passage forming portion and the second flow passage forming portion are laid over each other to form the flow passage and that the welding portion comes in contact with the transmission-side synthetic resin part;
• a sealing step of radiating laser light to the welding portion from a side of the transmission-side synthetic resin part to melt the welding portion to thereby weld the welding portion and the transmission-side synthetic resin part to each other to seal a periphery of the flow passage;
• and
• a joining step of joining the transmission-side synthetic resin part and the absorption-side synthetic resin part to each other.