A cooler comprising an inlet, an outlet, a first unit, and a second unit, - the inlet configured for feeding the cooler with coolant, - the outlet configured for discharging said coolant, - the first unit comprising a first plane for receiving a first part to be cooled, a first unit first fin, and a first unit second fin, o the first unit first fin extending from a first unit first root to a first unit first fin front, ∘ the first unit second fin extending from the first unit first root to a first unit second fin front, ∘ the first plane being in uninterrupted thermal contact with the first unit first root, ∘ the first unit first fin having a first unit first fin first surface, ∘ the first unit second fin having a first unit second fin first surface, - the second unit comprising a second unit first fin, - the second unit first fin having a second unit first fin first front, a second unit first fin first surface, and a second unit first fin second surface, - the second unit first fin located at least in part between the first unit first fin and the first unit second fin such that ∘ the first unit first root is adjacent to the second unit first fin first front leaving a first gap, ∘ the first unit first fin first surface is abutting the second unit first fin first surface, and ∘ the first unit second fin first surface is abutting the second unit first fin second surface, - at least one of the first unit first fin first surface and the second unit first fin first surface having a first corrugated structure, - the first corrugated structure forming first inbound channels between the first unit first fin first surface and the second unit first fin first surface, - at least one first inbound channel being configured for ∘ forming a first coolant inbound flow from the first unit first fin first front towards the first unit first root and ∘ causing the first coolant inbound flow to impinge and laterally widen on the first unit first root. - the inlet configured for feeding the cooler with coolant, - the outlet configured for discharging said coolant, - the first unit comprising a first plane for receiving a first part to be cooled, a first unit first fin, and a first unit second fin, o the first unit first fin extending from a first unit first root to a first unit first fin front, ∘ the first unit second fin extending from the first unit first root to a first unit second fin front, ∘ the first plane being in uninterrupted thermal contact with the first unit first root, ∘ the first unit first fin having a first unit first fin first surface, ∘ the first unit second fin having a first unit second fin first surface, o the first unit first fin extending from a first unit first root to a first unit first fin front, ∘ the first unit second fin extending from the first unit first root to a first unit second fin front, ∘ the first plane being in uninterrupted thermal contact with the first unit first root, ∘ the first unit first fin having a first unit first fin first surface, ∘ the first unit second fin having a first unit second fin first surface, - the second unit comprising a second unit first fin, - the second unit first fin having a second unit first fin first front, a second unit first fin first surface, and a second unit first fin second surface, - the second unit first fin located at least in part between the first unit first fin and the first unit second fin such that ∘ the first unit first root is adjacent to the second unit first fin first front leaving a first gap, ∘ the first unit first fin first surface is abutting the second unit first fin first surface, and ∘ the first unit second fin first surface is abutting the second unit first fin second surface, ∘ the first unit first root is adjacent to the second unit first fin first front leaving a first gap, ∘ the first unit first fin first surface is abutting the second unit first fin first surface, and ∘ the first unit second fin first surface is abutting the second unit first fin second surface, - at least one of the first unit first fin first surface and the second unit first fin first surface having a first corrugated structure, - the first corrugated structure forming first inbound channels between the first unit first fin first surface and the second unit first fin first surface, - at least one first inbound channel being configured for ∘ forming a first coolant inbound flow from the first unit first fin first front towards the first unit first root and ∘ causing the first coolant inbound flow to impinge and laterally widen on the first unit first root. ∘ forming a first coolant inbound flow from the first unit first fin first front towards the first unit first root and ∘ causing the first coolant inbound flow to impinge and laterally widen on the first unit first root.