Cal. Lab. Code § 5313

The appeals board or the workers’ compensation judge shall, within 30 days after the case is submitted, make and file findings upon all facts involved in the controversy and an award, order, or decision stating the determination as to the rights of the parties. Together with the findings, decision, order or award there shall be served upon all the parties to the proceedings a summary of the evidence received and relied upon and the reasons or grounds upon which the determination was made.