Abstract:
A circuit board container assembly includes a box (10) with internal side wall slots (16 and 17) for receiving dividers (21 and 22) in which are formed vertical slots (28, 29, 31 and 32) and into which are placed printed circuit boards (11). Thee dividers are color coded to indicate discrete offset positionings of edge tabs (23, 24, 26 and 27) on the respective dividers. The offset positioning of the edges permits the selection of dividers which are mounted in the wall slots to provide spacings of the bottoms of the divider slots at distances closely proximating the width of the circuit boards placed in the slots so that the boards are snugly held during transport of the box.

Description:
FIELD OF INVENTION 
     This invention relates to a container for receiving a number of printed circuit boards and snugly supporting the boards during subsequent transport of the container, and more particular, to a container assembly having circuit board insert support plates which may be selectively positioned to accommodate groups of circuit boards of different widths. 
     BACKGROUND OF THE INVENTION 
     During the manufacture of printed circuit boards, the boards must be transported from one assembly or fabricating station to another, e.g., from a component insertion station to a wave soldering station where loosely mounted components are solder bonded to the board. As the various assembly operations are completed, the value of the board increases considerably and great care must be exercised in handling the circuit boards to avoid any damage. The boards upon completion of each fabricating step are often placed in containers for transport to the next succeeding fabricating station. Thus the container must be designed to snugly hold the circuit boards during transport. 
     A problem exists in that various groups or codes of boards differ in size from one coded group to the next. It may be thus appreciated that it would be desirable to provide a transport container that may be easily modified to accommodate groups of circuit boards of different widths. Such a versatile or universal circuit board container is the subject of the present invention. 
     Various containers have been designed to receive and support a number of printed circuit boards for transport and/or subsequent storage. In one such container, as disclosed in U.S. Pat. No. 4,029,208 issued June 14, 1977 to H. Fickler et al., there is shown a plastic rectangular box having a pair of opposed grooved walls for receiving a pair of vertically grooved partitions. The partitions are placed in the walled grooves at distances approximating the widths of the circuit boards, whereafter, the boards may be slid into the support within the partition grooves. 
     In another circuit board container construction, as shown in U.S. Pat. No. 4,261,464 issued Apr. 14, 1981 to D. E. Maitland, a box is provided with equally spaced vertically extending grooves formed in the four interior box walls. A pair of locator members are fabricated with projecting pairs of tongues extending from opposite edges which are selectively seated in pairs of grooves formed in the opposed box walls. The locators are formed with closely spaced second tongues to project toward each other and thus provide sets of grooves for receiving end structures formed on opposite edges of a divider board. Grooves of different depths are formed on opposite sides of the divider board for receiving first ends of circuit boards while the other ends are received in the grooves formed in the box walls. By reversing the divider board, circuit boards of slightly different lengths can be accommodated. 
     There is still a need for a circuit board tote box assembly which can be quickly and accurately assembled with a minimum number of component parts to accommodate and snugly support the groups of circuit boards of different lengths. 
     SUMMARY OF INVENTION 
     This invention contemplates, among other things, a circuit board tote box assembly comprising a pair of vertically grooved dividers having projecting edge tongues which are offset from the center planes of the dividers and which may be selectively seated in opposed evenly spaced grooves formed in opposite interior side walls of a box to receive and snugly support groups of circuit boards having different widths. 
     More particularly, a plastic tote box is constructed with vertically extending grooves in a pair of opposed interior side walls. Color coded dividers with vertically extending circuit board receiving grooves are fabricated with oppositely projecting edge tongues. The pair of tongues on each divider are offset by a predetermined amount from the center plane of the board. The opposite sides of the divider are numerically code marked. 
     In use, the circuit boards are measured to provide information as to the proper selection of a pair of color coded dividers. The measured information also provides an indication of the manner of facing the appropriate sides of the dividers to provide a spacing between the dividers when mounted in the box which will permit the snug support of the circuit boards. The pair of dividers are mounted in the box by sliding the tongues along opposite side wall grooves, whereupon, the dividers are seated and spaced apart a distance closely proximating the width of the circuit board. Due to the proper selection of the color coded dividers and the appropriate facing of the divider grooves, pairs of grooves are presented to receive opposite edges of the circuit boards and snugly hold the boards during subsequent transport of the tote box. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other advantages and features of the invention will be apparent upon consideration of the following detailed specification in conjunction with the drawing wherein: 
     FIG. 1 is an exploded perspective view of a printed circuit board tote box embodying the principles of the present invention; 
     FIG. 2 is a top view showing the bottom of the tote box with instructions imprinted therein to enable one to select a pair of dividers to mount within the box and insure that the circuit boards are snugly held within the box; 
     FIG. 3 is a sectional view taken along plane 3--3 of FIG. 2 showing a divider seated within the tote box; 
     FIG. 4 is a top view of a divider illustrating a pair of offset mounting tongues; and 
     FIG. 5 is a sectional view taken along line 5--5 of FIG. 3 showing a cross-section of a color and numerically coded divider seated within the tote box. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and particularly to FIG. 1 there is shown a rectangular container 10 for receiving and supporting circuit boards 11 having components 12 mounted thereon. The container is constructed of moldable plastic and is provided with vertically extending and aligned sets of rounded top ribs 13 and 14 to define slots 16 and 17 formed in opposed side walls 18 and 19. The slots 16 and 17 may be formed on quarter (1/4) inch centers. The slots 16 and 17 are adapted to receive a pair of insert plates or dividers 21 and 22. More specifically, the insert plate 21 is fabricated at opposite ends with a pair of slide tabs or tongues 23 and 24 (see also FIG. 4) that are snugly fittable in a first pair of aligned, opposed slots 16 and 17 while the insert plate 22 is fabricated at opposite ends with a pair of slide tabs 26 and 27 that are snugly fittable in a second pair of aligned, opposed slots 16 and 17. The spacing between the inserted pair of plates 21 and 22 approximates the width of each board 11 of a group of circuit boards that are to be loaded into the container for subsequent transport to a fabricating station or a storage area. The insert plate 21 is provided on both sides with sets of vertically extending slots 28 and 29 of uniform depth and width. In a like manner, the insert plate 22 is provided on both sides with sets of vertically extending slots 31 and 32 of uniform depth and width. When a pair of insert plates 21 and 22 are slid into two pairs of spaced slots 16 and 17, printed circuit boards such as designated by the reference numeral 10 may be slid into pairs of facing aligned slots 29 and 31. 
     However, due to the 1/4 inch spacing between the container side wall slots 16 or 17, the circuit boards may still shift during transport resulting in possible damage or dislodgement of the components mounted on the circuit boards. What is needed is a more precise spacing between the insert plates 21 and 22 to prevent shifting of the board. This desirable result is obtainable by offsetting the slide tabs 23-24 and 26-27 by different amounts from center planes 36 and 37 passing through the respective plates 21 and 22. 
     More particularly, the slide tabs 23 and 24 on the plate 21 are offset a first amount, e.g., 0.09125, from the plane 36 passing through the plate, and the slide tabs 26 and 27 on the plate 22 are offset a different amount, e.g., 0.125, from the plane 37 passing through the center of the plate. By selecting different combinations of insert plates 21 and 22 and placing the plates within the slots 16 and 17 with different arrangements of side facings, it is possible to provide pairs of facing slots 29 and 31 which will receive a group of boards and hold the boards snugly during transport. The plates 21 and 22 are color and numerically coded; plate 21 may be molded with a blue tint or marked with a blue colored spot 38 and the plate 22 is molded with a yellow tint or marked with a yellow spot 39. The respective sides of the plate are numerically designated 1 and 2 (see FIG. 4). 
     Each divider plate, such as plate 21, is molded with an oppositely extending bottom flange 41 having a flat surface which may be abutted against a bottom panel 42 of the container. The flange is provided with a pair of transverse slots 43 and 44 to accommodate rails 46 and 47 formed to extend along the bottom panel 42. When a divider plate 21 or 22 is mounted in the container, the walls of slots in the flanges lock along the rails to increase stability and preclude bowing of the divider plate. The flange construction is also continued along opposite edges to provide flat outer surfaces with abut against the ribs 13 and 14 of the side walls 18 and 19. 
     The containers 10 are constructed of a low density polyethylene which has a foam-like interior with a hard slick surface having a surface resistivity of 10 5  to 10 14  ohms per square. In order to obtain this resistivity, a conductive or antistatic additive such &#34;Benstat&#34; material, manufactured by Bengal Corporation of Chatsworth, Calif., or &#34;Armostat&#34; material manufactured by the Armark Company of Burt, N.Y. are combined in small amounts (e.g., 0.3% of the weight of the polyethylene) with the polyethylene. This construction provides a light container having low friction surfaces wherein the plates 21 and 22 and the circuit board 33 may be easily assembled. It has been found that the hard surface on the container is a fair conductor of electricity so that electrostatic charges imparted to the container wall will be dissipated prior to passage to the circuit boards mounted within the container. Such a charge may originate from the user operator handling the container. Even small electrostatic charges if permitted to pass to the component mounted on the circuit boards may cause damage. In use, any charge imparted to the container will drain along the hard outer surface to a metallic support surface, such as a metal surface on a workbench or metallic transport skid. 
     In use, a group of boards of uniform widths to be transported are measured and the fractional inch dimension is converted to a decimal. Knowing the decimal and looking at the chart shown in FIG. 2, the proper pair of insert plates and plate facings may be determined. The characters for the chart are molded as intaglios in or embossments on the bottom of the container. In the alternative, the chart may also be formed as a separate piece and secured to the bottom of the container. More explicitly, assume that the board is 35/8 inches in length, or stated as a decimal, 3.625 inches in length. Taking the decimal 0.625 and referring to the chart in FIG. 3, it will be noted that the decimal designation 0.63 is the closest. The plate and facings arrangements may be then obtained by reading the notations to the right which indicates that a blue plate and a yellow plate should be selected and inserted in the container 10 so that side two on the blue plate faces side one on the yellow plate. 
     The attending operator places the first plate 21 into a pair of aligned slots 16 and 17. A sample board is then placed in a slot 29 and then the second plate is slid into a second pair of slots 16 and 17 so that the far end of the printed circuit board is received and seated within a slot 31. With the proper selection of plates 21 and 22, the edges of the printed circuit board will be fully seated within the aligned pairs of slots 29 and 31, and there will be a minimum amount of shifting of the boards during subsequent transport from one work location to the next. 
     As an alternative construction, the container may be marked with inch designations along the side walls 18 and 19 to apprise the operator as to the proper slot into which the second plate should be inserted. However, experience has shown that the user may set the pair of properly selected plates in the container with the aid of a sample board much faster than trying to figure out the proper slot selection from noting the inch dimension markings on the container. This is particularly true where more than a single pair of insert plates 21 and 23 are to be inserted to support more than one group of circuit boards. 
     Further, the container may be utilized to accommodate several groups of relatively narrow circuit boards in which instance more than two divider plates may be employed to divide the container into several components, each of which is of the proper size to receive one group of circuit boards. For example, two pairs insert plates 21 and 22 may be used and positioned to accommodate printed circuit boards of four different widths.