Open it and save it as a part.

Is the IGS  just a 2d wireframe or surfaces?

General Import Options

To set the general import options:

1.   Click Open (Standard toolbar) or File, Open. 

2. In the dialog box, set Files of type to one of the following, then click Options.

•   IGES (*.igs,*.iges) 

• STEP AP203/214 (*.step,*.stp)

• ACIS (*.sat)

• VDAFS (*.vda)

• Unigraphics (*.prt)

• Inventor Part (*.ipt)

3.   Select from the options described below, then click OK to return to the Open dialog box. 

4. Select the file to open, then click Open to import the file as a SolidWorks document.

Surface/solid entities

•   Try forming solid(s).

B-REP mapping. Attempts to import the model by directly mapping topologies using boundary representation (BREP) data. In general, this mode is faster than knitting, especially for complex models. If you select Try forming solid(s) but not B-REP mapping, the SolidWorks application attempts to knit the surfaces into solids.

•   Knit surface(s). Imports as surfaces and attempts to knit the surfaces. 

• Do not knit. Imports as surfaces and prevents surfaces from knitting.

• Merge Entities (for Inventor Part, SAT, STEP, or IGES).To preserve split lines (redundant geometry) and form a solid when Knit surface(s) or Do not knit is selected.

Free point/curve entities

•   Import as sketch(es). Imports data as 2D and 3D sketch data. Recommended when importing free curves. Free points and 2D sketches import as 2D sketches. 2D and 3D curves import as 3D sketches. 

• Import as 3D curves. Imports data as 3D curve data. 2D and 3D curves import as curves. Free points and 2D sketches import as 2D sketches.

Import multiple bodies as parts

(IGES, STEP, UG, and ACIS only). Imports a multibody part as separate part documents in an assembly document. When cleared, the multibody part imports as a part document with multiple bodies.

Perform full entity check and repair errors

Checks and repairs errors. Import performance is slower because the software spends time checking and (when possible) repairing the model entities.

Automatically run Import Diagnostics (Healing)

When importing a file, Import Diagnostics runs automatically. When cleared, a prompt appears for each import action asking if you want to run Import Diagnostics.

Customize curve tolerance

Customizes the tolerance when importing models with very small entities (smallest values on the order of 1.0e-6 to 1.0e-7 meters). When cleared, SolidWorks uses internal tolerance settings, which are too large to properly import and display these small models. Enter a tolerance in the box.

Unit

Set the units of measure for the imported file.

•   File specified unit. Use the units of the imported file. 

• Document template specified unit. Use the units specified in the SolidWorks template files under Tools, Options, System Options, Default Templates.

IGES

Show IGES levels. Displays the IGES-In Surfaces, Curves, and Levels dialog box if the IGES file contains curves or different levels (or layers).

STEP

Map configuration data. Imports STEP file configuration data plus geometric data. Clear to import only geometric data.

UG

Import tool bodies. Tool bodes are used to construct the final bodies. Clear to import only the final bodies.