An RF package includes a substrate mountable on a base plate, a non-conductive cover overlying the substrate, and quasi-serpentine stepped source leads attached to an upper surface of the substrate and extending from at least one of a pair of opposite sides of the upper surface of the substrate to tapered lower surfaces of the cover. The cover includes a recess to receive the substrate. The recess includes stress distribution surface areas to engage and press outer edge portions of opposite sides of the substrate against a base plate or heat sink. The tapered lower surfaces of the cover engage with and press against the stepped source leads when securing the RF package to the base plate or heat sink using one or more fasteners or bolts. The cover includes structural features to improve preferential deformation when a mounting force is applied.
1. An RF package, comprising:
a substrate mountable on a base plate;
a non-conductive cover overlying the substrate and including:
a recess configured to receive the substrate, the recess forming a stress distribution surface area to engage and press outer edge portions of opposite sides of the substrate against the base plate;
one or more tapered lower surfaces extending from the recess toward outer edge portions of the cover;
one or more stepped source leads extending from at least one of a pair of opposite sides of an upper surface of the substrate to the one or more tapered lower surfaces of the cover;
one or more gate and drain leads extending from at least one of a pair of opposite sides of an upper surface of the substrate;
one or more dies disposed on the substrate;
one or more conductors electrically coupling the one or more gate leads, drain leads, and stepped source leads to the one or more dies; and
a cavity disposed within the cover to receive the one or more dies, the one or more conductors, and at least portions of the one or more gate leads, drain leads, and stepped source leads, wherein the cover further includes:
a first section having a first thickness between the cavity and the top surface of the cover to provide rigidity to the central portion of the cover;
one or more additional sections having a second thickness between the cavity and the top surface of the cover, the second thickness less than the first thickness; and
a curved section connecting the first section to the one or more additional sections,
wherein the one or more additional sections and the curved section are configured to evenly distribute stress of the cover during preferential deformation thereof when securing the one or more stepped source leads and the substrate to the base plate.
2. The RF package of claim 1 , wherein the cover further includes a bolt hole for receiving a bolt in each outer edge portion to clamp the cover against the base plate and wherein the one or more tapered lower surfaces of the cover face the base plate and are angled relative to the base plate to provide a progressively increasing mounting force on the stepped source leads as the bolts are tightened.
3. The RF package of claim 1 , wherein each of the one or more stepped sources leads includes:
a first section coupled to the upper surface of the substrate, the upper surface of the substrate defining a horizontal dimension of the first section;
a second section extending in a slanted direction from the first section at an angle relative to the horizontal dimension of the first section; and
a third section extending from the second section at an angle relative to the slanted direction of the second section.
4. The RF package of claim 3 , wherein the first, second, and third sections of the source leads form a contiguous stepped source lead located beneath the cover.
5. previously presented) The RF package of claim 3 , wherein the one or more tapered lower surfaces of the cover are structured to engage with and press against the third section of the one or more stepped source leads.
6. The RF package of claim 3 , wherein the recess includes one or more notches disposed at outer edges thereof, the one or more notches structured to provide:
stress concentration outwardly toward edges of the cover; and
deformation of the cover about the first and second sections of the one or more stepped source leads.
7. The RF package of claim 1 , wherein the base plate is a heat sink attachable to the one or more stepped source leads.
8. The RF package of claim 1 , wherein the cover comprises a material having a resistance to creep, high electrical insulation, high yield strength, and low dielectric loss.
9. The RF package of claim 1 , further comprising one or more bolt holes arranged in the cover and aligned with corresponding openings in the one or more stepped source leads, the one or more bolt holes configured to receive one or more bolts to secure the substrate and the one or more stepped source leads to the base plate.