A polyolefin microporous membrane is disclosed. The membrane has a width of not less than 100 mm, and a variation range of an F25 value in a width direction is not greater than 1 MPa. The F25 value is a value obtained by dividing a load at 25% elongation of a sample of the laminated polyolefin microporous membrane as measured with a tensile testing machine by a cross-sectional area of the sample.

A polyolefin microporous membrane is disclosed. The membrane has a width of not less than 100 mm, and a variation range of an F25 value in a width direction is not greater than 1 MPa. The F25 value is a value obtained by dividing a load at 25% elongation of a sample of the laminated polyolefin microporous membrane as measured with a tensile testing machine by a cross-sectional area of the sample.

A method for manufacturing a monolithic component with integral branching points, including providing a sheet metal comprising a first section and a second section, thinning, via rollforming, the first section of the sheet metal, splitting, via split-rollforming, the second section of the sheet metal in a plane parallel to a surface area of the second section, such that a first flange portion and a second flange portion is formed.