Patent IT-1225749-B (IT)
Title: Device with independently micrometrically adjustable crystal matrices for the double symmetrical exposure to ultraviolet rays of printed electrical circuits of various thickness
Inventor: NEVIO TRAVERSA
IPC: H05K/
Filed: 1988-12-20
Granted: 1990-11-26
Abstract: The equipment concerned, which we call "Cassetto D.E.S. 90 D.R." (Table no. 1) can be used in the exposure machines for future printed electric circuits and possibly also for other uses.  In order to clarify what is described here below it is advisable to consult the description of the terminology used (page 15/16) and the key of the details (page 16/17/18/19/20).  The said box, apart from other potential possibilities, fulfils the conditions for exposing to ultraviolet rays, also called UV (Table no. 13 - phase 3), a future printed electric circuit, also called "board" (detail E) and inserted between two crystal matrices (details B and D).  Exposure of the board to the UV rays takes place at the same time on both sides (Table no. 13 - phase 1-2-3 and 4) and for greater success with the operation it is necessary that the two crystal matrices and the board inserted between these are compressed one against the other.  The compression of the crystal matrices in relation to the board inserted between them is achieved by the action of atmospheric pressure external to the box and internal depression, obtained via a vacuum pump and a vacuum sealed system inside the box made by us (details b, b1, h2, p, q1).  With regard to the box designed by us, (Table no. 1), this was made for our convenience with two plates made of light alloy, which we call "lower support plate" (detail A) and "upper" (detail C) (alternatively it is also possible to use other replacement materials); the said support plates are interconnected by two "special" hinges (detail a) and at the opening stage, the upper support plate is replaced by the force (pressure) of two gas springs of suitable length and power (detail r).  On the lower support plate (detail A) the adjustment (detail d + e) and holding (detail d2 + e1) devices of the lower crystal matrix (detail B) are positioned as well as the devices for treating and extracting the board (detail s + s1) and the vacuum sealed system for the lower crystal matrix (detail c).  On the upper support plate (detail C) are positioned the adjustment (detail h + i) and support (detail n) devices for the upper crystal matrix, the vacuum sealed system (detail q1 + q2 + q3) between the upper support plate and the said crystal matrix, as well as the external peripheral vacuum sealed system (detail p) suitable for vacuum sealing between the lower and upper support plate of the box itself.  As previously stated the "board" at the exposure stage is inserted between two crystal matrices (detail E + B + D), which bring to the face which comes into contact with the "board" the matrices to be reproduced on the said "boards" (photographic matrices, film matrices or other, for example chrome tracks etc.)  The lower crystal matrix is adjusted in relation to the lower face of the "board" (detail d + e) and the upper one in relation to the upper face of the same (detail h + i) and in addition the "board" is held outside the crystal matrices by two metallic positioning pins (detail s1).  The upper crystal matrix can be adjusted in height by means of adequate thicknesses (detail t) and made suitable for accepting "boards" of various thickness, which can vary from a thickness of a few tenths of a millimetre up to a few millimetres (Table no. 6 - drawing 6a +6b), furthermore the vacuum seal (detail q3) between upper crystal matrix and upper support plate (detail C) adapts automatically to the variation in thickness of the exposed board (Table no. 8 - drawing 6a + 6b).  Obviously, during the production stage the "board" being exposed to UV rays is inserted, then the "box" is closed (Table no. 13 phase 1), the vacuum is made, in this way creating the pressure between crystal matrices and "board" inserted between them (details E + B + D) and at this point the "box" can be inserted in the machine for exposure to UV rays (Table no. 13 - phases 2 and 3).  Normally machines for this type of production have two boxes, of which alternately one is inside the machine and the other outside (Table no. 13 phase 1 and 3).