A process for providing through plated holes in a substrate by screen printing provides uniformly thick plating of the holes. One side of the substrate is screen plated while being subjected to an underpressure between 10 and 200 gr/cm.sup.2 from a chamber fed by a large volume vacuum vat. When treating the other side of the substrate, vacuum may be increased up to 2.5 times the first underpressure.
A method and apparatus for marking or erasing a marking on a semiconductor chip package having leads. The apparatus comprises a circular disk has many pockets on one surface near its circumference suitable for holding semiconductor chips. Each pocket has a pedestal rising from the bottom of the pocket and suitable for supporting the bottom portion of a semiconductor chip package. The edges of the pocket and the pedestal define between them space suitable for housing the leads of the package. The pedestal has a hole therein which can be evacuated so that the package is held to the pedestal by atmospheric pressure so that the top surface of the package may be marked or in marking thereon can be erased. Thus the package is held to the pedestal by sufficient force for the marking or erasing process. The leads of the package are therefore not bent or otherwise disturbed. Rotation of the disk allows the packages to be sequentially marked or erased.
A screen printing machine has a table on which a substrate is to be put, a substrate adjusting device on the table to adjust the position of the substrate on the table, a screen plate capable of being placed on the table, a squeegee movable on the plate, a suction unit connected with the table to apply suction to the substrate through through holes of the substrate, a measuring device arranged in the suction unit to measure the degree of vacuum in the suction unit, and an adjusting device arranged in the suction unit to adjust the degree of vacuum.
An apparatus and method utilize vacuum injected molding of a liquid in a plurality of mold cells for solidification therein. An injection head includes spaced apart vacuum and injection slots positionable atop a mold plate in flow communication with the mold cells therein. Relative axial sliding is effected between the injection head and the mold plate for sequentially evacuating gas from the mold cells using a continuous vacuum followed in turn by sequentially injecting into the evacuated mold cells the liquid from a continuous source thereof. Sliding of the injection head over the mold plate automatically provides self valving for sequentially evacuating and filling the mold cells from the same side of the mold plate. In a preferred embodiment, the vacuum and injection slots are linked together at the mold plate so that surface tension of the liquid restrains flow of the liquid from the injection slot to the vacuum slot while allowing gas flow therebetween for effecting the vacuum in the mold cells.
An apparatus and a method for filling high aspect ratio holes in electronic substrates that can be advantageously used for filling holes having aspect ratios larger than 5:1 are disclosed. In the apparatus, a filler plate and a vacuum plate are used in conjunction with a connection means such that a gap is formed between the two plates to accommodate an electronic substrate equipped with high aspect ratio via holes. The filler plate is equipped with an injection slot while the vacuum plate is equipped with a vacuum slot such that when a substrate is sandwiched therein, via holes can be evacuated of air and injected with a liquid simultaneously from a bottom side and a top side of the substrate. The present invention novel apparatus and method allows the filling of via holes that have small diameters, i.e., as small as 10 .mu.m, and high aspect ratios, i.e., at least 5:1 to be filled with an electrically conductive material such as a solder or a conductive polymer such that vias or interconnects can be formed in electronic substrates. The present invention apparatus and method can be advantageously used in fabricating substrates for display panels by forming conductive vias and interconnects for placing a voltage potential on pixel display elements formed on the display panels.
Flexible multilayer printed circuit boards are disclosed which utilize adhesiveless laminates interconnected in a generally superposed relationship by a conductive adhesive. In one embodiment, the adhesiveless laminates have relatively thin conductive layers and metallized through holes which exhibit high delamination resistance. The metallized through holes preferably have a thickness of at most about 25 microns, yet they are capable of withstanding multilayer assembly processes. High flexibility, reliability, packaging density, and environmental resistance are consequently available in a thin multilayer construction. In a further embodiment, adhesiveless dielectric layers are interposed between adhesiveless laminates to electrically insulate portions thereof. The adhesiveless dielectric layers may define relatively small apertures therein, thus providing greater packaging density for a multilayer printed circuit board.
