Two-shot MID

The main advantages of two-shot molding are high geometric design freedom and suitability for high-volume production with uniform precision and low costs per unit. A combination of electric circuitry and mechanicai functionality is the typical requirements list for a two-shot MID such as a snap hook that enables the electrical part to connect to other components. 

Ultrasonic wire bonding on MID has to allow for other factors influencing bond-ability that are of minor significance at best in the context of conventional printed-circuit boards or ceramic substrates. For example, the thickness of the plating, metallization surface roughness, and the type of substrate structuring are all of crucial importance. With two-shot MID the structural design and the mechanical... 

Two-shot molding for instrument panels started in mid-1990s. Will likely grow. 

MID antennas have become mainstream in recent years, and nowhere more so than in the mobile-communications sector. Units of this kind are manufactured in very high numbers in Asia. Molex announced the production of its twenty millionth LPKF-LDS antenna [76] back in 2009, and a large proportion of MID antennas are two-shot moldings. The sector is further expanding to include tablet PCs, with demand leaning more toward larger antenna structures. RFID antennas for very widely varying applications constitute yet another sector. 

The following sections set out the purely materials-related and tool-related prerequisites for the two processes now most commonly used in MID production two-shot molding and laser direct structuring (LDS). Chapter 3 of this book deals in depth with the workflows, possibilities, and boundary conditions associated with these manufacturing processes. It also contains information about the production methods such as hot embossing and film insert molding, neither of which is considered in more detail here from the materials point of view. 

In the past, two-shot molding or two-shot injection molding generally referred to a process in which a first shot of material is subsequently enclosed within a second shot. In MID technology, however, the process is one in which the second-shot plastic compound is applied on top of the first shot. In the course of time two main versions of this basic process have established themselves for MID technology [48] ... 

MID was the technology of choice on account of the challenging three-dimensional design requirements. Even though it had to satisfy a raft of regulatory requirements, the HF antenna structure was developed within a matter of weeks. LDS technology was used in the early phase of development so that layout adaptations could be incorporated quickly. Once RF capability had been verified, the LDS structure was transferred to a two-shot injection-mold design for a fast ramp-up to series production. 

The pressure sensor is a two-shot molding. Production volume is on the high side of 10 million units per year. The printed-circuit board is contacted on the MID by conductive-adhesive gluing (isotropic conductive adhesive). Nonconductive adhesive is also applied for mechanical location. The contact pins of the MID are tiny bumps to which the conductive adhesive is applied in the dispensing process. [143]... 

The MID is manufactured by two-shot molding. The metallizable material PC/ ABS (polycarbonate, acrylonitrile butadiene styrene) of the first shot is enciosed in the second shot of PC (polycarbonate). The PC/ABS forms what wiii become the conductors, and the PC is the package. The pins contact the PCB and have to be dimensionaiiy stable, so precision injection moiding is a must. The PC/ABS is chemicaiiy metaiiized with Cu-Ni-Au. 

Two-shot molding was chosen for economy, on account of the high-volume production rate of some 1.5 million units per year. Price per unit is therefore low, despite high investment outlay for the complex molding tool. A 3D assembly line was set up for component placement on the MID blanks and final assembly of the module. 

To demonstrate calibration linearity and transferability using a fiber-optic probe and simple peak-area methods, the solution spectra of four solutions of phenylisocyanate in acetone were used. The mid-infrared spectrum of most isocyanates are characterized by a sharp band, sometimes exhibiting shoulders, at 2250-2285 cm which is assigned to the asymmetric stretch of the -N C=0 group. In the spectra of acetone solutions of phenylisocyanate, this band appears at 2261 cm with a substantial shoulder at 2283 cm. Figure 1 shows an expanded view of the band, displayed in a screen shot from the GRAMS peak-fitting software with two Lorentzian peaks fitted at 2261 and 2283 cm. ... 

---